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Highly Active Ag-Cu Nanocrystal Catalyst-Coated Brewer’s Spent Grain Biochar for the Mineralization of Methyl Orange and Methylene Blue Dye Mixture

Université Paris Cité, CNRS, ITODYS, 75013 Paris, France
Department of Chemistry, St. Joseph’s University (Autonomous), Bangalore 560027, India
Université Paris Est, CNRS, ICMPE (UMR 7182), 94320 Thiais, France
Authors to whom correspondence should be addressed.
Catalysts 2022, 12(11), 1475;
Submission received: 3 October 2022 / Revised: 8 November 2022 / Accepted: 14 November 2022 / Published: 18 November 2022
(This article belongs to the Special Issue Nanoparticles in the Catalysis)


The aim of the present work is to valorise the brewing industry’s waste, i.e., brewer’s spent grain (BSG), into functional biocarbon for environmental catalysis applications. In this context, cost-effective and environmentally friendly biochar support coated with in-situ-generated Ag-Cu nanocrystals, was developed via the wet impregnation of BSG biomass powder with copper (II) nitrate trihydrate and silver nitrate aqueous solution prior to pyrolysis at moderate temperature (500 °C). Small-size homogenously distributed Ag-Cu nanocrystals (≤80 nm) on the surface of the biochar (Biochar@Ag-Cu) were observed by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Elemental compositions were determined by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX). The crystalline nature of the nanoparticles was confirmed by X-ray powder diffraction (XRD). Information about the thermal stability of the materials and quality were obtained by thermogravimetric analysis (TGA) and Raman, respectively. The potentiality of the Biochar@Ag-Cu catalyst in the field of pollutant removal is demonstrated by taking methyl orange and methylene blue as model dyes. A kinetics study was performed and analyzed by UV–vis spectroscopy. Its highly active catalytic nature is proved by the complete mineralization of the methyl orange dye (100%) through oxidative degradation. The reusability of the catalyst has shown 96% removal efficiency after 3 cycles. The linear plot of −Ln (CA/C0) vs. time (R2 = 0.9892) reveals that the mineralization of the methyl orange dye follows pseudo-first-order kinetics (k = 0.603 × 10−2 min−1). A methyl orange + methylene blue dye mixture degradation study has revealed the faster kinetics of the present catalyst towards methylene blue degradation. The current study suggests that BSG Biochar@Ag-Cu can be a potential candidate in contribution towards SDG 6.

Graphical Abstract

1. Introduction

The carbon allotropes family is diversified with many fascinating structures and hybridisation [1]. The last two decades has witnessed the emergence of wonder nanomaterials such as carbon nanotubes [2], graphene [3], fullerene [4], carbon nano-horns, and nano-onions [5], which have been tested in numerous technologies such as water treatments, batteries, fuel cells, tissue engineering, pharmaceuticals, etc. [6].
However, with global environmental and climate change concerns, the focus is on the recycling and valorisation of waste [7]. Thus, it is no surprise that researchers are shifting their focus towards low-cost biochar [8,9,10], also coined “the new black” ( last accessed 6 November 2022). It is basically derived from plant or animal waste and synthesised through a thermochemical process [11,12]. Their porosity, water-holding capacity, high surface area, pH and nutritious nature [13] make it applicable to plenty of different purposes, such as dye adsorption [14], filler in rubber composites [15], the recovery of sour anaerobic digesters [16] and engineering and agricultural applications [17], to mention a few.
Every year, plenty of dye effluents contaminate water bodies. A cationic dye, methylene blue (MB), and an anionic dye, methyl orange (MO), have been studied as model pollutants [18]. The sources of the dyes are textiles, leather, plastics, pharmaceuticals, paper industries, etc. [19,20,21]. MB exposure may cause burning sensations, nausea, breathing difficulties, diarrhoea and vomiting. Large doses can even cause severe headaches, mental confusion, chest pains and methemoglobinemia [22,23]. The dyes are genotoxic, mutagenic and carcinogenic as well as a big threat to aquatic life [24]. There are different methods of water treatment, such as adsorption [25,26,27,28], degradation [29], mineralisation [30], coagulation [31], sedimentation, and ion exchange processes [32]. Though adsorption is a low-cost energy process, the fate of molecules after adsorption is still challenging. Just normal degradation can remove the primary molecules; however, the degraded product can be either toxic or non-toxic [33]. In contrast, total mineralization removes all the organic parts and results in purified water [34].
Silver (Ag) nanoparticles are well known for their antibacterial, anti-fungal, antioxidant, anti-fouling, anti-cancer, anti-viral, anti-quorum sensing, anti-angiogenic, anti-inflammatory, anti-proliferative [35,36], and osteogenic properties [37]. Silver-containing compounds or their hybrids possess catalytic activity for dye degradation [38,39]. Copper nanoparticles also exhibit antibacterial, antioxidant and anti-diabetic activity [40] as well as being heterogeneous Fenton-like catalysts [41]. It is no surprise that working with bimetallic nanoparticles results in the synergistic effects of both nanoparticles in a single nanocomposite [42]. Recent studies have found that copper-containing Ag composites are very efficient and effective in the degradation of water effluents [43]. Ag-Cu nanoparticles are applicable for dye degradation by oxidative or reductive degradation for both cationic or anionic dyes [44]. Thus, Ag brings antibacterial and catalytic properties and their activity is further enhanced by Cu incorporation, which is a low-cost material compared to noble metals. Ag/Cu properties are tunable by doping with other nanoparticles [45,46].
Brewer’s spent grain (BSG) is a by-product of the brewing industry. Its huge production is an opportunity for biomass waste valorization and, thus, a contribution towards a circular economy [47,48]. They are utilized for animal feed, biogas production, etc. This is also an exciting opportunity to exploit BSG for utilization in producing biochar [49,50]. Biochar can act as a catalyst as it has rich functional groups and a good porous structure [51]. Furthermore, impregnating biochar with catalytic nanoparticles improves its catalytic efficiency in water purification. Hence, we used wet chemical synthesis [42,52] to obtain homogeneous small-sized nanoparticles on biochar.
In the literature, there are some methods reported to coat biochar with Ag-Cu bimetallic nanoparticles. Snoussi et al. [53] used arylated biochar (SO3H-biochar) to disperse Ag-Cu nanoparticles on their surface via the reduction of silver and copper ions using natural extracts. Hosny et al. [54] reported on the preparation of biochar using Atriplex halimus biomass, followed by modification with AgNPs and CuNPs. A. halimus was used as a stablising and reducing agent. Wang et al. used Ag/Cu2O/cotton fabric for the treatment of dye wastewater [55]. Cu-Ag/C was also utilized for the hydroxylation of benzene (HOB) [56].
A thorough literature survey has revealed that there is not even a single work on copper silver bimetallic particle/biochar composites for the degradation of methyl orange (Figure 1). As a matter of fact, we have gone through several combinations or sequences of keywords using the Web of Science search engine to look for the most relevant papers, but no close or relevant results were returned by this important database. Hence, we were motivated to impregnate copper and silver nanoparticles on brewer’ spent grain biochar via a simple and reproducible wet impregnation technique. MO and MB dyes were taken as model pollutants [57] to test the catalytic activity towards dye degradation. The present material can be a potential candidate for environmental applications. Ultimately, the aim of the present work is to contribute towards Sustainable Development Goal (SDG) 6 [58].

2. Results and Discussion

The sample was characterized using different techniques. It is noted that the untreated biochar, biochar coated with Ag, biochar coated with Cu and biochar coated with Ag-Cu are abbreviated as Biochar, Biochar@Ag, Biochar@Cu and BiocharAg-Cu, respectively.

2.1. Crystallinity of the Material

Figure 2 depicts the XRD spectra of different biochar samples. In all the cases, the peaks at 2θ = 50.8 and 59.4 are ascribed to the Cu (111) and Cu (002) planes (reference code 98-062-7113) [59] in the sample Biochar@Cu (Figure 2d), respectively. The peak in sample Biochar@Ag (Figure 2c) at 2θ = 44.8, 52.0 and 76.7 are due to the planes Ag (111), Ag (002) and Ag (022) (reference code 98-005-3759) [60]. These characteristic peaks of both Ag and Cu are present in the sample Biochar@Ag-Cu (Figure 2b), representing the successful impregnation of the biochar with Ag-Cu nanoparticles (reference code 98-060-4104) [61]. One can note that there are clear, distinct phases, Cu and Ag. Note that the Ag diffraction peaks appear broader in the Biochar@Ag sample compared to the Biochar@Ag-Cu sample. It may or may not be a kind of core (Ag)–shell (Cu) particle, where copper precipitation limits Ag growth. This is also supported by the fact that the copper signal is more intense than that of silver in the Biochar@Ag-Cu sample.

2.2. Surface Chemical Composition of the Catalyst

XPS characterisation was carried out to understand the chemical composition of the sample. It is obvious that just the biochar sample lacks Ag and Cu. Further, when it is coated with Ag or Cu or Ag-Cu, it is clearly found in the XPS survey spectra (Figure 3). The surface composition (in atomic percentage) is reported in Table 1. In the sample Biochar@Ag-Cu, the percentage of Ag and Cu are 0.4 and 0.7, respectively.
The high-resolution spectra of Ag3d (Figure 4a) indicate that the silver is in a metallic state [62]. Figure 4b is also an indication of Cu in the metallic state, but of course, due to the very reactive nature of the nanoparticles, slight oxidation cannot be neglected [63,64,65]. Interestingly, the absence of the shake-up satellite peak in the Cu2p region suggests that copper nitrate has been completely reduced to the metallic state [66]. The pyrrolic and pyridinic [67] components of N1s are clearly seen in Figure 4c. It is likely that these nitrogen-containing species contribute to the tight immobilization of the metallic nanoparticles on the biochar.

2.3. Surface Morphology of the Material and Bulk Composition

The study of the surface morphology of the biochar and the nanoparticle-impregnated biochar was carried out by FESEM, as shown in Figure 5. It is quite obvious that the surface of the pristine biochar (Figure 5a) is smoother compared to one with the presence of nanoparticles (Figure 5b–d). It is observed that the biochar impregnated with Cu nanoparticles (Figure 5c) is of slightly larger size compared to biochar with Ag nanoparticles (Figure 5b). The Ag-Cu nanoparticle (Figure 5d) size (≤80 nm) is in between the Ag and Cu nanoparticles. In all cases, the shape of the nanoparticles is quasi-spherical. The distribution of Ag nanoparticles and Ag-Cu on biochar is much better than just Cu nanoparticles. The homogeneity and dispersibility of nanoparticles on the biochar surface is a clear indication of efficient methodology. The current method is simple and avoids multistep procedures and the use of stabilising and reducing agents [54,68]. This also means that biochar derived from Brewer’s spent grains is an excellent support to disperse Ag-Cu nano-catalysts on its surface compared to another biomass-derived biocarbon. In addition, the support is very necessary to avoid particle agglomeration, as reported in the literature [69]. EDX mapping is provided in Figure 6. This indicates the uniform distribution of the probed elements, signifying that the biochar samples are homogeneous. The atomic percentage compositions obtained from EDX mapping are as follows: C (79.43 %), N (4.85%), O (10.49%), Mg (0.58%), Si (0.14%), P (1.84%), S (0.22%), Ca (0.46%), Cu (1.14 %) and Ag (0.85%). Furthermore, these entire biomass-derived carbon materials should be characterised by a CHNS elemental analyser for more accurate measurements. This will give an idea about the correlation between the pyrolysis temperature and the H/C atomic ratio [70].
The TEM images are displayed in Figure 7. Figure 7a–c depict the small-size nature of the nanoparticles, which are homogeneously distributed over the biochar surface. Particle sizes are mostly less than 50 nm, but sometimes, larger ones are found. Figure 7d shows the lamellar arrangements. The clear morphology of the nanoparticle, which was in association with biochar, was difficult to observe, so some spots were found where some free nanoparticles were present (Figure 7e). The presence of free nanoparticles can be due to the strong sonication used to disperse Biochar@Ag-Cu in ethanol for drop casting on the TEM grid. Different kinds of shapes of nanoparticles exist. Here, particle phase segregation exists. This image (Figure 7e) also highlights the occurrence of moires. Moires are the formation of fringes generated by interference between periodic elements or the superposition of the interference images of crystals with different orientations or inter-reticular distances (dhkl) [71]. Selected area electron diffraction (SAED) patterns (Figure 7f) show dhkl 0.239 (111), 0.210 (200) and 0.147(220) correspond to Ag with a lattice parameter expansion of 1.80% (0.416 +/− 0.004 nm) and dhkl 0.210 (111), 0.187 (200), and 0.130 (220) are related to Cu [72,73,74], with a lattice parameter expansion of 2.2 % (0.370 +/− 0.005 nm). The SAED patterns also reveal the crystalline nature of the nanoparticles.

2.4. Study of the Degree of Graphitization

Raman characterisation was performed in order to understand the purity of the sample and the extent of graphitisation [75,76]. The curve fitting of Raman spectra (Figure 8) shows mostly six peaks: D (heteroatoms and defects), G (extent of graphitization), SL (hydrogen circulation along periphery), GL (carbonyl function), V (sp2-C) and S (alkyl-alkyl ether) [77,78,79]. It is noticed from the Raman analysis that decoration with Ag-Cu resulted in broad peaks as well as an increase in alkyl-alkyl ether functionalities. The metal-induced enhanced graphitization of biochar was reported elsewhere [53,80] and is consistent with the findings reported herein.

2.5. Thermal Stability

The thermogram of different biochar samples is given in Figure 9. It is found that the thermal stability of the material decreases with the presence of nanoparticles, which catalyses the decomposition. The higher the activity of the catalyst, the more it facilitates the decomposition of the biochar. The maximum effect is observed with Ag-Cu (Figure 9d). This can also be a sign of the high catalytic activity of Ag-Cu compared to just Ag and Cu. Further, the weight % remaining after 700 °C (Figure 9d) is also more (36% approx.) compared to Biochar@Ag (27%), Biochar@Cu (25% approx.) and Biochar (20% approx.). This phenomenon can be explained based on the fact that the formation of silver and copper oxides has high stability (oxidation of Ag and Cu occurs under air after heating during TGA analysis). Finally, the results are supported by the DTG curve [81], as shown in Figure 10, where Tmwl (temperature of maximum weight loss rate) [82] is lowest (398 °C) for Biochar@Ag-Cu and highest for just Biochar (602 °C), indicating they are the least and most stable, respectively. Based on this, the stability order is as follows: Biochar@Ag-Cu < Biochar@Cu < Biochar@Ag < Biochar.

2.6. Dye Degradation

The applicability of the present catalyst in the field of dye degradation is demonstrated by taking MO and MB dyes as model pollutants. The mechanism of MO dye degradation is given in Figure 11 [33,83]. It is found that after 6 h, MO is completely mineralized (Figure 12), which results in completely colourless water, resembling drinkable water, as shown in Figure 13.
MO dye mineralization efficiency reaches 100% after 6 h of catalytic treatment in the presence of H2O2 (Figure 12a,b). Although UV–vis studies show no sign of a degradation product, the confirmation of complete mineralisation is best provided by total organic carbon (TOC) content measurements [84,85]. A study on the reusability of the catalyst was carried out. After three cycles, the percentage removal efficiency was found to be as high as 96%. The plot of −Ln (CA/CO) vs. time (Figure 12c) follows a linear relationship with R2 = 0.9892 and indicates it follows a pseudo-first-order model, as shown below:
Ln C t C 0 = Kt
Considering the pseudo-first-order model reaction, where K is the apparent rate constant (min−1), [C]0 = the initial concentration (mgL−1) and [C]t = the concentration at time “t” (mgL−1).
The comparison of mineralisation efficiency, with and without catalysts and H2O2, is also shown in Figure 14. It is noticed that the best performance is observed with Biochar@Ag-Cu in association with H2O2. A mixture of methyl orange and methylene blue solutions revealed that the present catalyst shows faster kinetics for methylene blue degradation than methyl orange degradation (Figure 15).
Table 2 compares different methods for MO degradation and their efficiency. It is found that the current method is highly attractive and cost-effective as it provides higher performances over other methods in terms of mineralisation efficiency, owing to the simple catalyst preparation method and operation under daylight exposure. More importantly, there is not even a single study on brewer’s spent grain Biochar@Ag-Cu for methyl orange degradation. Thus, the current material may have high potential in the field of water treatment, particularly for removing pollutants released from the textile industry.

3. Materials and Methods

3.1. Chemicals

Distilled water was used for all experimental purposes. Copper (II) nitrate trihydrate (99%) and silver nitrate (minimum 99.5%) were received from Acros organics and Rectapur (Geel, Belgium), respectively. BSG was obtained as a by-product of lager beer (it consists of a mixture of malts, i.e., barley and malt) from Belorge (Villers-sur-Mer, France). Hydrogen peroxide (30%) was purchased from Sigma-Aldrich, Burlington, VT, USA.

3.2. Apparatus

A coffee mill/grinder (Duronic, model: CG250, Voltage: 220–240 V, made in China) was used to grind the BSG biomass after washing and drying. FESEM was performed with emission current = 30μA and accelerating voltage = 5 kV (working distance = 6.9 mm). Firstly, a double-sided carbon tape is pasted on a sample holder to attach a cleaned silica plate. A biochar sample dispersed in ethanol via sonication is drop-casted on this silica plate and air-dried. This machine has an inbuilt EDX detector. WD was around 9 mm for the EDX analysis. TEM analysis was performed on JEOL TEM-2100 Plus electron microscope (Tokyo, Japan). Raman characterization was carried out on a Horiba HR 800 spectrometer (Kyoto, Japan). TGA characterisation was done in air, from RT to 800 °C, at a heating rate of 10 °C/min, using an HP DSC SETARAM SENSYS EVO (Caluire, France). XRD analysis was carried out on an X’Pert PRO PANalytical instrument (Cambridge, UK), where operating voltage and tube current were kept at 40 kV and 40 mA, respectively. XPS analysis was carried out using a Thermo Scientific K Alpha+ apparatus (Waltham, MA, USA) with the pass energy of 200 and 80 eV for the survey scan (step size = 1 eV) and high-resolution spectra (step size = 0.1 eV), respectively. A UV–visible kinetic study was carried out using a Cary 4000 UV–vis spectrophotometer (SpectraLab Scientific Inc., Markham, ON, Canada).

3.3. Synthesis of Ag-Cu-Impregnated Biochar Catalyst

As-received brewer’s spent grains were first washed with tap water (2 times) and distilled water (2 times). Then, it was dried in the oven at 150 °C for 4 h and 30 min. Later, it was ground using a coffee mill for 2 min [91]; 1 g of the BSG biomass powder was soaked in a copper (II) nitrate trihydrate solution (241.6 mg in 10 mL). In another experiment, 1 g of biomass powder was soaked in silver nitrate (169.8 mg in 10 mL distilled water). Lastly, 1 g of biomass powder was soaked in a copper (II) nitrate trihydrate (241.6 mg) and silver nitrate (169.8 mg) solution made to 10 mL. All three samples were dried in an oven at 60 °C overnight. After that, it was subjected to pyrolysis, with conditions as follows: type of method (P10 KOH Free), N2 flow rate (1 L min−1), ramp (20 °C min−1), temperature (500 °C), residence time (1 h), and cooling time (1 h). This moderate-temperature pyrolysis method was applied to decrease the produced polycyclic aromatic hydrocarbons (PAHs). It is well known in the literature that synthesis at 500 °C causes biochar with lower PAH contents (483–2100 μg/Kg) [92]. Table 3 reports the % yield of the different biochar samples.

3.4. Dye Degradation Test

For the test, 5 mg of the catalyst was added to 10 mL of the 20 ppm MO solution. Further, 2 mL of H2O2 was added, and the solution was stirred for different intervals of time (1, 2, 3, 4, 5 and 6 h). A kinetics study was carried out using UV–visible spectroscopy. The test of the reusability of the catalyst was carried out by adding the same amount of MO solution and H2O2 in the same beaker. This was repeated until 3 cycles were completed. In the current work, we considered parameters such as the amount of the H2O2, catalyst (amount of catalyst and doping ratio), etc., to obtain the optimal conditions of degradation. As reported, a 6-hour duration was optimum for total mineralisation after trying at 1, 2, 3, 4, 5, and 6 h durations. The doping ratio of Cu and Ni was 1 mmole:1 mmole per 1 g of BSG powder. It is important to note, from our own experience and the ongoing research work, that increasing the loading of metal salts further is very likely to cause the agglomeration of the nanoparticles, hence increasing particle size and probably decreasing efficiency. Moreover, different pH conditions were not considered as our plan was to study only neutral pH for practical applications. For the effect of pH on dye mineralisation using biochar-based catalysts, the reader is referred to [93,94,95].

4. Conclusions

An efficient Ag-Cu nanoparticle-coated brewer’s spent grain biochar has been developed via the wet impregnation method, followed by pyrolysis under an inert atmosphere at 500 °C. The composite catalyst and the related materials were characterised using several techniques. Although the current characterisation does not reveal carbide, the presence of carbide cannot be ignored. Nanoparticles mostly fall below 50 nm, but sometimes, bigger particles are also there. Current materials have been successfully used in depolluting water from harmful chemicals, such as MO by 100% (k = 0.603 × 10−2 min−1), and also utilised to treat a MO and MB dye mixture. A reusability study has shown 96% MO removal efficiency after three cycles. Oxidative degradation has played an important role in achieving this goal. A dye mixture degradation study has revealed the fast kinetics of MB degradation by catalyst compared to methyl orange. From the above, the methods reported in this work are simple, efficient and very easily reproducible. The Biochar@catalyst materials have a high potential in dye mineralisation, hence the interest in using them to treat textile industry wastewater. Particularly, brewer’s spent grains can not only be used to feed farm animals (SDG 12: responsible consumption and production) but also be advantageously explored in designing high-performance catalysts. The BSG-based materials are, thus, expected to play an important role in the environmental sector and fulfil SDG 6.

Author Contributions

Conceptualization, A.K.B., Y.S. and M.M.C.; methodology, L.B., A.K.B., Y.S., M.J., S.A. and M.M.C.; validation, all authors; formal analysis, L.B., A.K.B., Y.S., L.M., C.M.D.S., S.A. and M.M.C.; investigation, L.B., A.K.B., Y.S., L.M., C.M.D.S., S.A. and M.M.C.; resources, S.A. and M.M.C.; data curation, A.K.B., Y.S. and M.M.C.; writing—original draft preparation, A.K.B.; writing—review and editing, all authors; visualization, A.K.B., Y.S. and M.M.C.; supervision, A.K.B., Y.S., M.J., S.A. and M.M.C.; project administration, A.K.B., S.A. and M.M.C.; funding acquisition, A.K.B., S.A. and M.M.C. All authors have read and agreed to the published version of the manuscript.


This research was funded by “Bourse Wallonie-Bruxelles International Excellence World (N° imputation—101386, and Article Budgetaire—”. Financial support was also given by the French Ministry of Research, ANR (Agence Nationale de la Recherche), and CGI (Commissariat à l’Investissement d’Avenir) through a Labex SEAM (ANR-11-LABX-086, ANR-11-IDEX-0502) grant.

Data Availability Statement

Not applicable.


We would like to thank Benoit Boisanfray from Bel Orge brewery (located at 6 Rue des Grives, F-14640 Villers-sur-Mer, Calvados, Normandy, France) for providing us with the gift of brewer’s spent grains. We are grateful to the experimental officers at the ITODYS lab for their assistance with Raman, FE-SEM/EDX, and XPS characterization.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.


  1. Meunier, V.; Ania, C.; Bianco, A.; Chen, Y.; Choi, G.B.; Kim, Y.A.; Koratkar, N.; Liu, C.; Tascon, J.M.D.; Terrones, M. Carbon science perspective in 2022: Current research and future challenges. Carbon N. Y. 2022, 195, 272–291. [Google Scholar] [CrossRef]
  2. Iijima, S. Helical microtubules of graphitic carbon. Nature 1991, 354, 56–58. [Google Scholar] [CrossRef]
  3. Novoselov, K.S.; Geim, A.K.; Morozov, S.V.; Jiang, D.; Zhang, Y.; Dubonos, S.V.; Grigorieva, I.V.; Firsov, A.A. Electric Field Effect in Atomically Thin Carbon Films. Science 2004, 306, 666–669. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  4. Kroto, H.W.; Heath, J.R.; O’Brien, S.C.; Curl, R.F.; Smalley, R.E. C60: Buckminsterfullerene. Nature 1985, 318, 162–163. [Google Scholar] [CrossRef]
  5. Ugarte, D. Curling and closure of graphitic networks under electron-beam irradiation. Nature 1992, 359, 707–709. [Google Scholar] [CrossRef] [PubMed]
  6. Sridharan, R.; Monisha, B.; Kumar, P.S.; Gayathri, K.V. Carbon nanomaterials and its applications in pharmaceuticals: A brief review. Chemosphere 2022, 294, 133731. [Google Scholar] [CrossRef] [PubMed]
  7. Pandey, D.; Daverey, A.; Dutta, K.; Yata, V.K.; Arunachalam, K. Valorization of waste pine needle biomass into biosorbents for the removal of methylene blue dye from water: Kinetics, equilibrium and thermodynamics study. Environ. Technol. Innov. 2022, 25, 102200. [Google Scholar] [CrossRef]
  8. Bhakta, A.K.; Fiorenza, R.; Jlassi, K.; Mekhalif, Z.; Ali, A.M.A.; Chehimi, M.M. The emerging role of biochar in the carbon materials family for hydrogen production. Chem. Eng. Res. Des. 2022, 188, 209–228. [Google Scholar] [CrossRef]
  9. Azan, N.A.A.M.; Sagadevan, S.; Mohamed, A.R.; Azazi, A.H.N.; Suah, F.B.M.; Kobayashi, T.; Adnan, R.; Kaus, N.H.M. Solar Light-Induced Photocatalytic Degradation of Ciprofloxacin Antibiotic Using Biochar Supported Nano Bismuth Ferrite Composite. Catalyst 2022, 12, 1269. [Google Scholar] [CrossRef]
  10. Ioannidi, A.A.; Vakros, J.; Frontistis, Z.; Mantzavinos, D. Tailoring the Biochar Physicochemical Properties Using a Friendly Eco-Method and Its Application on the Oxidation of the Drug Losartan through Persulfate Activation. Catalyst 2022, 12, 1245. [Google Scholar] [CrossRef]
  11. Adeniyi, A.G.; Ighalo, J.O.; Onifade, D.V. Biochar from the thermochemical conversion of Orange (Citrus sinensis) peel and albedo: Product quality and potential applications. Chem. Africa 2020, 3, 439–448. [Google Scholar] [CrossRef] [Green Version]
  12. Das, R.; Panda, S.N. Preparation and applications of biochar based nanocomposite: A review. J. Anal. Appl. Pyrolysis 2022, 167, 105691. [Google Scholar] [CrossRef]
  13. Weber, K.; Quicker, P. Properties of biochar. Fuel 2018, 217, 240–261. [Google Scholar] [CrossRef]
  14. Ali, Y.A.E.H.; Ahrouch, M.; Lahcen, A.A.; Abdellaoui, Y.; Stitou, M. Recent Advances and Prospects of Biochar-based Adsorbents for Malachite Green Removal: A Comprehensive Review. Chem. Africa 2022. [Google Scholar] [CrossRef]
  15. Greenough, S.; Dumont, M.-J.; Prasher, S. The physicochemical properties of biochar and its applicability as a filler in rubber composites: A review. Mater. Today Commun. 2021, 29, 102912. [Google Scholar] [CrossRef]
  16. Aramrueang, N.; Zhang, R.; Liu, X. Application of biochar and alkalis for recovery of sour anaerobic digesters. J. Environ. Manag. 2022, 307, 114538. [Google Scholar] [CrossRef]
  17. Harussani, M.M.; Sapuan, S.M. Development of Kenaf Biochar in Engineering and Agricultural Applications. Chem. Africa 2022, 5, 1–17. [Google Scholar] [CrossRef]
  18. Kumar K, A.; Shobham; Panwar, J.; Gupta, S. One-pot synthesis of metal oxide-clay composite for the evaluation of dye removal studies: Taguchi optimization of parameters and environmental toxicity studies. Environ. Sci. Pollut. Res. 2022. [Google Scholar] [CrossRef]
  19. Shrestha, P.; Jha, M.K.; Ghimire, J.; Koirala, A.R.; Shrestha, R.M.; Sharma, R.K.; Pant, B.; Park, M.; Pant, H.R. Decoration of Zinc Oxide Nanorods into the Surface of Activated Carbon Obtained from Agricultural Waste for Effective Removal of Methylene Blue Dye. Materials 2020, 13, 5667. [Google Scholar] [CrossRef]
  20. Blue, M.; Orange, M. Critical Review on the Photodegradation Ability of Graphene and its Derivatives against Malachite Green, Methylene Blue, and Methyl Orange. Lett. Appl. NanoBioScience 2023, 12, 1–30. [Google Scholar] [CrossRef]
  21. Kotp, Y.H. Fabrication of cerium titanate cellulose fiber nanocomposite materials for the removal of methyl orange and methylene blue from polluted water by photocatalytic degradation. Environ. Sci. Pollut. Res. 2022, 29, 81583–81608. [Google Scholar] [CrossRef] [PubMed]
  22. Othman, N.H.; Alias, N.H.; Shahruddin, M.Z.; Bakar, N.F.A.; Him, N.R.N.; Lau, W.J. Adsorption kinetics of methylene blue dyes onto magnetic graphene oxide. J. Environ. Chem. Eng. 2018, 6, 2803–2811. [Google Scholar] [CrossRef]
  23. Ghosh, D.; Bhattacharyya, K.G. Adsorption of methylene blue on kaolinite. Appl. Clay Sci. 2002, 20, 295–300. [Google Scholar] [CrossRef]
  24. Waghchaure, R.H.; Adole, V.A.; Jagdale, B.S. Photocatalytic degradation of methylene blue, rhodamine B, methyl orange and Eriochrome black T dyes by modified ZnO nanocatalysts: A concise review. Inorg. Chem. Commun. 2022, 143, 109764. [Google Scholar] [CrossRef]
  25. Benjelloun, M.; Miyah, Y.; Bouslamti, R.; Nahali, L.; Mejbar, F.; Lairini, S. The Fast-Efficient Adsorption Process of the Toxic Dye onto Shells Powders of Walnut and Peanut: Experiments, Equilibrium, Thermodynamic, and Regeneration Studies. Chem. Africa 2022, 5, 375–393. [Google Scholar] [CrossRef]
  26. Dabagh, A.; Bagui, A.; Abali, M.; Aziam, R.; Chiban, M.; Sinan, F.; Zerbet, M. Increasing the Adsorption Efficiency of Methylene Blue by Acid Treatment of the Plant Carpobrotus edulis. Chem. Africa 2021, 4, 585–598. [Google Scholar] [CrossRef]
  27. Nazir, M.A.; Najam, T.; Zarin, K.; Shahzad, K.; Javed, M.S.; Jamshaid, M.; Bashir, M.A.; Shah, S.S.A.; Rehman, A.U. Enhanced adsorption removal of methyl orange from water by porous bimetallic Ni/Co MOF composite: A systematic study of adsorption kinetics. Int. J. Environ. Anal. Chem. 2021. [Google Scholar] [CrossRef]
  28. Rigueto, C.V.T.; Alessandretti, I.; da Silva, D.H.; Rosseto, M.; Loss, R.A.; Geraldi, C.A.Q. Agroindustrial Wastes of Banana Pseudo-stem as Adsorbent of Textile Dye: Characterization, Kinetic, and Equilibrium Studies. Chem. Africa 2021, 4, 1069–1078. [Google Scholar] [CrossRef]
  29. Ajiboye, T.O.; Oyewo, O.A.; Marzouki, R.; Brahmia, A.; Onwudiwe, D.C. Synthesis of AgBiS2/gC3N4 and its application in the photocatalytic reduction of Pb (II) in the matrix of methyl orange, crystal violet, and methylene blue dyes. Ceram. Int. 2022, in press. [Google Scholar] [CrossRef]
  30. Stanley, R.; Jebasingh, J.A.; Vidyavathy, S.M.; Stanley, P.K.; Ponmani, P.; Shekinah, M.E.; Vasanthi, J. Excellent Photocatalytic degradation of Methylene Blue, Rhodamine B and Methyl Orange dyes by Ag-ZnO nanocomposite under natural sunlight irradiation. Optik 2021, 231, 166518. [Google Scholar] [CrossRef]
  31. Luo, X.; Liang, C.; Hu, Y. Comparison of Different Enhanced Coagulation Methods for Azo Dye Removal from Wastewater. Sustainability 2019, 11, 4760. [Google Scholar] [CrossRef] [Green Version]
  32. Mukherjee, A.; Goswami, N.; Dhak, D. Photocatalytic Remediation of Industrial Dye Waste Streams Using Biochar and Metal-Biochar Hybrids: A Critical Review. Chem. Africa 2022. [Google Scholar] [CrossRef]
  33. Kgatle, M.; Sikhwivhilu, K.; Ndlovu, G.; Moloto, N. Degradation Kinetics of Methyl Orange Dye in Water Using Trimetallic Fe/Cu/Ag Nanoparticles. Catalysts 2021, 11, 428. [Google Scholar] [CrossRef]
  34. Dos Santos, A.J.; Sires, I.; Martínez-Huitle, C.A.; Brillas, E. Total mineralization of mixtures of Tartrazine, Ponceau SS and Direct Blue 71 azo dyes by solar photoelectro-Fenton in pre-pilot plant. Chemosphere 2018, 210, 1137–1144. [Google Scholar] [CrossRef]
  35. Jeevanandam, J.; Krishnan, S.; Hii, Y.S.; Pan, S.; Chan, Y.S.; Acquah, C.; Danquah, M.K.; Rodrigues, J. Synthesis approach-dependent antiviral properties of silver nanoparticles and nanocomposites. J. Nanostruct. Chem. 2022, 12, 809–831. [Google Scholar] [CrossRef]
  36. Snoussi, Y.; Sifaoui, I.; Khalil, A.M.; Bhakta, A.K.; Semyonov, O.; Postnikov, P.S.; Michely, L.; Pires, R.; Bastide, S.; Barroso, J.E.-P.; et al. Facile synthesis of silver decorated biochar as a novel and highly active biosourced anti-kinetoplastid agent. Mater. Today Commun. 2022, 32, 104126. [Google Scholar] [CrossRef]
  37. Nazarov, D.; Ezhov, I.; Yudintceva, N.; Shevtsov, M.; Rudakova, A.; Kalganov, V.; Tolmachev, V.; Zharova, Y.; Lutakov, O.; Kraeva, L.; et al. Antibacterial and Osteogenic Properties of Ag Nanoparticles and Ag/TiO2 Nanostructures Prepared by Atomic Layer Deposition. J. Funct. Biomater. 2022, 13, 62. [Google Scholar] [CrossRef]
  38. Mahmood, K.; Amara, U.; Siddique, S.; Usman, M.; Peng, Q.; Khalid, M.; Hussain, A.; Ajmal, M.; Ahmad, A.; Sumrra, S.H.; et al. Green synthesis of Ag@CdO nanocomposite and their application towards brilliant green dye degradation from wastewater. J. Nanostruct. Chem. 2022, 12, 329–341. [Google Scholar] [CrossRef]
  39. Shahzad, K.; Hussain, S.; Nazir, M.A.; Jamshaid, M.; ur Rehman, A.; Alkorbi, A.S.; Alsaiari, R.; Alhemiary, N.A. Versatile Ag2O and ZnO nanomaterials fabricated via annealed Ag-PMOS and ZnO-PMOS: An efficient photocatalysis tool for azo dyes. J. Mol. Liq. 2022, 356, 119036. [Google Scholar] [CrossRef]
  40. Ameena, S.; Rajesh, N.; Anjum, S.M.; Khadri, H.; Riazunnisa, K.; Mohammed, A.; Kari, Z.A. Antioxidant, Antibacterial, and Anti-diabetic Activity of Green Synthesized Copper Nanoparticles of Cocculus hirsutus (Menispermaceae). Appl. Biochem. Biotechnol. 2022, 194, 4424–4438. [Google Scholar] [CrossRef]
  41. Zhu, G.; Jin, Y.; Ge, M. Simple and green method for preparing copper nanoparticles supported on carbonized cotton as a heterogeneous Fenton-like catalyst. Colloids Surfaces A Physicochem. Eng. Asp. 2022, 647, 128978. [Google Scholar] [CrossRef]
  42. Omiri, J.; Snoussi, Y.; Bhakta, A.K.; Truong, S.; Ammar, S.; Khalil, A.M.; Jouini, M.; Chehimi, M.M. Citric-Acid-Assisted Preparation of Biochar Loaded with Copper / Nickel Bimetallic Nanoparticles for Dye Degradation. Colloids Interfaces 2022, 6, 18. [Google Scholar] [CrossRef]
  43. Arasi, K.; Arasu, S.; Raja, A.G.; Rajaram, R. Photocatalytic Degradation of Effluent water by CuO @ Ag Core—Shell Nanoparticles as Effective Catalyst under Irradiation of UV-light. Mater. Today Proc. 2022, 68, 556–563. [Google Scholar] [CrossRef]
  44. Tantawy, H.R.; Nada, A.A.; Baraka, A.; Elsayed, M.A. Novel synthesis of bimetallic Ag-Cu nanocatalysts for rapid oxidative and reductive degradation of anionic and cationic dyes. Appl. Surf. Sci. Adv. 2021, 3, 100056. [Google Scholar] [CrossRef]
  45. Passi, M.; Pal, B. Influence of Ag/Cu photodeposition on CaTiO3 photocatalytic activity for degradation of Rhodamine B dye. Korean J. Chem. Eng. 2022, 39, 942–953. [Google Scholar] [CrossRef]
  46. Dong, S.; Lian, X.; Chen, S.; Li, H.; Liu, E.; Xu, K. Kinetic analysis and mechanism study on the photocatalytic degradation of 2,4-dinitrophenylhydrazine over surface plasmonic Ag/Cu/TiO2 composite. React. Kinet. Mech. Catal. 2021, 134, 485–499. [Google Scholar] [CrossRef]
  47. Singh, E.; Mishra, R.; Kumar, A.; Shukla, S.K.; Lo, S.-L.; Kumar, S. Circular economy-based environmental management using biochar: Driving towards sustainability. Process Saf. Environ. Prot. 2022, 163, 585–600. [Google Scholar] [CrossRef]
  48. Bolwig, S.; Mark, M.S.; Happel, M.K.; Brekke, A. Beyond animal feed? The valorisation of brewers’ spent grain. In From Waste to Value; Taylor & Francis: Abingdon, UK, 2019; pp. 107–121. [Google Scholar]
  49. Sieradzka, M.; Kirczuk, C.; Kalemba-rec, I.; Mlonka-m, A.; Magdziarz, A. Pyrolysis of Biomass Wastes into Carbon Materials. Energies 2022, 15, 1941. [Google Scholar] [CrossRef]
  50. Gupta, R.; Pandit, C.; Pandit, S.; Gupta, P.K.; Lahiri, D.; Agarwal, D.; Pandey, S. Potential and future prospects of biochar-based materials and their applications in removal of organic contaminants from industrial wastewater. J. Mater. Cycles Waste Manag. 2022, 24, 852–876. [Google Scholar] [CrossRef]
  51. Zhao, C.; Shao, B.; Yan, M.; Liu, Z.; Liang, Q.; He, Q.; Wu, T.; Liu, Y.; Pan, Y.; Huang, J.; et al. Activation of peroxymonosulfate by biochar-based catalysts and applications in the degradation of organic contaminants: A review. Chem. Eng. J. 2021, 416, 128829. [Google Scholar] [CrossRef]
  52. Snoussi, Y.; Sifaoui, I.; El Garah, M.; Khalil, A.M.; Barroso, J.E.; Jouini, M.; Ammar, S.; Lorenzo-Morales, J.; Chehimi, M.M. Green, zero-waste pathway to fabricate supported nanocatalysts and anti-kinetoplastid agents from sugarcane bagasse. Waste Manag. 2023, 155, 179–191. [Google Scholar] [CrossRef]
  53. Snoussi, Y.; El Garah, M.; Khalil, A.M.; Chehimi, M.M. Immobilization of biogenic silver-copper nanoparticles over arylated biochar from sugarcane bagasse: Method and catalytic performance. Appl. Organomet. Chem. 2022, 36, e6885. [Google Scholar] [CrossRef]
  54. Hosny, M.; Fawzy, M.; Eltaweil, A.S. Phytofabrication of bimetallic silver-copper / biochar nanocomposite for environmental and medical applications. J. Environ. Manag. 2022, 316, 115238. [Google Scholar] [CrossRef]
  55. Wang, L.; Mao, H.; Li, Z.; Wang, C.; Gao, D. Immobilizing Ag / Cu2O on cotton fabric to enhance visible light photocatalytic activity. New J. Chem. 2020, 44, 20759–20769. [Google Scholar] [CrossRef]
  56. Tian, K.; Liu, W.; Zhang, S.; Jiang, H. One-pot synthesis of a carbon supported bimetallic Cu–Ag NPs catalyst for robust catalytic hydroxylation of benzene to phenol by fast pyrolysis of biomass waste. Green Chem. 2016, 18, 5643–5650. [Google Scholar] [CrossRef]
  57. Al-qaradawi, S.; Salman, S.R. Photocatalytic degradation of methyl orange as a model compound. J. Photochem. Photobiol. A Chem. 2002, 148, 161–168. [Google Scholar] [CrossRef]
  58. Ho, L.; Alonso, A.; Eurie Forio, M.A.; Vanclooster, M.; Goethals, P.L.M. Water research in support of the Sustainable Development Goal 6: A case study in Belgium. J. Clean. Prod. 2020, 277, 124082. [Google Scholar] [CrossRef]
  59. Tokola, E.; Kantola, M. Annales Academiae Scientiarum Fennicae. Ser. A6 Phys. 1967, 223, 1–10. [Google Scholar]
  60. Vegard, L. Vega. Phys. Rev. 1922, 20, 424–432. [Google Scholar]
  61. Weibo, L.; Yinghong, Z.; Junqin, L. No Title. J. Alloys Compd. 1993, 191, 187–189. [Google Scholar]
  62. Maria Ferraria, A.; Patrícia Carapeto, A.; do Rego, A.M. X-ray photoelectron spectroscopy: Silver salts revisited. Vacuum 2012, 86, 1988–1991. [Google Scholar] [CrossRef]
  63. Biesinger, M.C. Advanced analysis of copper X-ray photoelectron spectra. Surf. Interface Anal. 2017, 49, 1325–1334. [Google Scholar] [CrossRef]
  64. Biesinger, M.C.; Lau, L.W.M.; Gerson, A.R.; Smart, R.S.C. Applied Surface Science Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn. Appl. Surf. Sci. 2010, 257, 887–898. [Google Scholar] [CrossRef]
  65. Biesinger, M.C.; Hart, B.R.; Polack, R.; Kobe, B.A.; Smart, R.S.C. Analysis of mineral surface chemistry in flotation separation using imaging XPS. Miner. Eng. 2007, 20, 152–162. [Google Scholar] [CrossRef]
  66. Almheiri, S.; Ahmad, A.A.L.; Le Droumaguet, B.; Pires, R.; Mohamed, A.A.; Chehimi, M.M. Development of Latent Fingerprints via Aryldiazonium Tetrachloroaurate Salts on Copper Surfaces: An XPS Study. Langmuir 2020, 36, 74–83. [Google Scholar] [CrossRef]
  67. Kabir, S.; Artyushkova, K.; Serov, A.; Kiefer, B.; Atanassov, P. Binding energy shifts for nitrogen-containing graphene-based electrocatalysts—Experiments and DFT calculations. Surf. Interface Anal. 2016, 48, 293–300. [Google Scholar] [CrossRef]
  68. Saad, A.G.; Gebreil, A.; Kospa, D.A.; El-Hakam, S.A.; Ibrahim, A.A. Integrated solar seawater desalination and power generation via plasmonic sawdust-derived biochar: Waste to wealth. Desalination 2022, 535, 115824. [Google Scholar] [CrossRef]
  69. Yin, C.; Khan, A.; Gao, Q.; Li, Q.; Zhou, X.; Liu, X.; Xu, A.; Li, X. Synergistic activation of peroxymonosulfate for efficient aqueous p -nitrophenol degradation with Cu (II) and Ag (I) in Ag2Cu2O3. Sep. Purif. Technol. 2022, 291, 120934. [Google Scholar] [CrossRef]
  70. Xiao, X.; Chen, Z.; Chen, B. H/C atomic ratio as a smart linkage between pyrolytic temperatures, aromatic clusters and sorption properties of biochars derived from diverse precursory materials. Sci. Rep. 2016, 6, 22644. [Google Scholar] [CrossRef] [Green Version]
  71. Fulong, D.; Yongrning, X. Nano-moire method. ACTA Mech. Sin. 1999, 15, 283–288. [Google Scholar] [CrossRef]
  72. Dou, Q.; Li, Y.; Wong, K.W.; Ng, K.M. Facile synthesis of nearly monodisperse AgCu alloy nanoparticles with synergistic effect against oxidation and electromigration. J. Mater. Res. 2019, 34, 2095–2104. [Google Scholar] [CrossRef]
  73. Fodjo, E.K.; Canlier, A.; Kong, C.; Yurtsever, A.; Guillaume, P.L.A.; Abe, M.; Patrice, F.T.; Tohei, T.; Sakai, A. Facile Synthesis Route of Au-Ag Nanostructures Soaked in PEG. Adv. Nanopart. 2018, 7, 37–45. [Google Scholar] [CrossRef] [Green Version]
  74. Korneva, A.; Straumal, B.; Kilmametov, A.; Chulist, R.; Cios, G.; Baretzky, B.; Zięba, P. Dissolution of Ag Precipitates in the Cu–8wt.% Ag Alloy Deformed by High Pressure Torsion. Materials 2019, 12, 447. [Google Scholar] [CrossRef]
  75. Tran, H.N.; Tomul, F.; Ha, N.T.H.; Nguyen, D.T.; Lima, E.C.; Le, G.T.; Chang, C.-T.; Masindi, V.; Woo, S.H. Innovative spherical biochar for pharmaceutical removal from water: Insight into adsorption mechanism. J. Hazard. Mater. 2020, 394, 122255. [Google Scholar] [CrossRef]
  76. Mcdonald-wharry, J. 2013–2014 Survey of Chars Using Raman Spectroscopy. J. Carbon Res. 2021, 7, 63. [Google Scholar] [CrossRef]
  77. Inoue, J.; Yoshie, A.; Tanaka, T.; Onji, T.; Inoue, Y. Disappearance and alteration process of charcoal fragments in cumulative soils studied using Raman spectroscopy. Geoderma 2017, 285, 164–172. [Google Scholar] [CrossRef] [Green Version]
  78. Pusceddu, E.; Montanaro, A.; Fioravanti, G.; Santilli, S.F.; Foscolo, P.U.; Criscuoli, I.; Raschi, A.; Miglietta, F. Comparison between Ancient and Fresh Biochar Samples, A Study on The Recalcitrance of Carbonaceous Structures During Soil Incubation. Int. J. New Technol. Res. 2017, 3, 39–46. [Google Scholar]
  79. Feng, D.; Zhao, Y.; Zhang, Y.; Sun, S.; Gao, J. Steam Gasification of Sawdust Biochar Influenced by Chemical Speciation of Alkali and Alkaline Earth Metallic Species. Energies 2018, 11, 205. [Google Scholar] [CrossRef] [Green Version]
  80. Wu, Y.; Sun, Y.; Liang, K.; Yang, Z.; Tu, R.; Fan, X.; Cheng, S.; Yu, H.; Jiang, E.; Xu, X. Enhancing Hydrodeoxygenation of Bio-oil via Bimetallic Ni-V Catalysts Modified by Cross-Surface Migrated-Carbon from Biochar. ACS Appl. Mater. Interfaces 2021, 13, 21482–21498. [Google Scholar] [CrossRef]
  81. Chen, Y.; Cui, Z.; Ding, H.; Wan, Y.; Tang, Z.; Gao, J. Cost-Effective Biochar Produced from Agricultural Residues and Its Application for Preparation of High Performance Form-Stable Phase Change Material via Simple Method. Int. J. Mol. Sci. 2018, 19, 3055. [Google Scholar] [CrossRef] [Green Version]
  82. Riva, L.; Cardarelli, A.; Andersen, G.J.; Buø, T.V.; Barbanera, M.; Bartocci, P.; Fantozzi, F.; Nielsen, H.K. On the self-heating behavior of upgraded biochar pellets blended with pyrolysis oil: Effects of process parameters. Fuel 2020, 278, 118395. [Google Scholar] [CrossRef]
  83. Wang, B.; Xu, M.; Chi, C.; Wang, C.; Meng, D. Degradation of methyl orange using dielectric barrier discharge water falling film reactor. J. Adv. Oxid. Technol. 2017, 20, 20170021. [Google Scholar] [CrossRef]
  84. Xu, J.; Sun, M.; Zhang, C.; Wu, M.; Fu, D. Electrochemical mineralization of direct blue 71 with boron-doped diamond anodes: Factor analysis and mechanisms study. J. Environ. Chem. Eng. 2022, 10, 107031. [Google Scholar] [CrossRef]
  85. Yaghoot-nezhad, A.; Saebnoori, E.; Danaee, I.; Elahi, S.; Bahrami, N.; Khosravi-nikou, M.R. Evaluation of the oxidative degradation of aromatic dyes by synthesized nano ferrate (VI) as a simple and effective treatment method. J. Water Process Eng. 2022, 49, 103017. [Google Scholar] [CrossRef]
  86. Shahzad, K.; Najam, T.; Bashir, M.S.; Nazir, M.A.; ur Rehman, A.; Bashir, M.A.; Shah, S.S.A. Fabrication of Periodic Mesoporous Organo Silicate (PMOS) composites of Ag and ZnO: Photo-catalytic degradation of methylene blue and methyl orange. Inorg. Chem. Commun. 2021, 123, 108357. [Google Scholar] [CrossRef]
  87. Shan, R.; Lu, L.; Gu, J.; Zhang, Y.; Yuan, H.; Chen, Y.; Luo, B. Photocatalytic degradation of methyl orange by Ag/TiO2/ biochar composite catalysts in aqueous solutions. Mater. Sci. Semicond. Process. 2020, 114, 105088. [Google Scholar] [CrossRef]
  88. Lu, L.; Shan, R.; Shi, Y.; Wang, S.; Yuan, H. A novel TiO2/biochar composite catalysts for photocatalytic degradation of methyl orange. Chemosphere 2019, 222, 391–398. [Google Scholar] [CrossRef]
  89. Ren, Y.; Liu, X.; Li, H.; Wang, X.; Jing, X. Synthesis and visible light photocatalytic performance of HC/BiOBr/ Bi12TiO20 microspheres. Chem. Phys. Lett. 2022, 797, 139584. [Google Scholar] [CrossRef]
  90. Wang, Z.; Li, Y.; Xie, X.; Wang, Z. Bifunctional MnFe2O4/ chitosan modified biochar composite for enhanced methyl orange removal based on adsorption and photo-Fenton process. Colloids Surfaces A Physicochem. Eng. Asp. 2021, 613, 126104. [Google Scholar] [CrossRef]
  91. Bhakta, A.K.; Snoussi, Y.; El Garah, M.; Ammar, S.; Chehimi, M.M. Brewer’s Spent Grain Biochar: Grinding Method Matters. J. Carbon Res. 2022, 8, 46. [Google Scholar] [CrossRef]
  92. Wang, J.; Odinga, E.S.; Zhang, W.; Zhou, X.; Yang, B.; Waigi, M.G.; Gao, Y. Polyaromatic hydrocarbons in biochars and human health risks of food crops grown in biochar-amended soils: A synthesis study. Environ. Int. 2019, 130, 104899. [Google Scholar] [CrossRef]
  93. Yao, Y.; Hu, H.; Zheng, H.; Hu, H.; Tang, Y.; Liu, X.; Wang, S. Nonprecious bimetallic Fe, Mo-embedded N-enriched porous biochar for efficient oxidation of aqueous organic contaminants. J. Hazard. Mater. 2022, 422, 126776. [Google Scholar] [CrossRef]
  94. Wang, R.; Huang, D.; Liu, Y.; Zhang, C.; Lai, C.; Wang, X.; Gong, X.-M.; Zeng, G.-M.; Duan, A.; Xu, P.; et al. Recent advances in biochar-based catalysts: Properties, applications and mechanisms for pollution remediation. Chem. Eng. J. 2019, 371, 380–403. [Google Scholar] [CrossRef]
  95. Chu, J.; Kang, J.; Park, S.; Lee, C. Application of magnetic biochar derived from food waste in heterogeneous sono-Fenton-like process for removal of organic dyes from aqueous solution. J. Water Process Eng. 2020, 37, 101455. [Google Scholar] [CrossRef]
Figure 1. Literature survey of work related to biochar, copper, silver and methyl orange (source: Web of Science, dated 5 September 2022).
Figure 1. Literature survey of work related to biochar, copper, silver and methyl orange (source: Web of Science, dated 5 September 2022).
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Figure 2. XRD patterns of (a) Biochar, (b) Biochar@Ag-Cu, (c) Biochar@Ag and (d) Biochar@Cu.
Figure 2. XRD patterns of (a) Biochar, (b) Biochar@Ag-Cu, (c) Biochar@Ag and (d) Biochar@Cu.
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Figure 3. XPS survey scans of biochar and nanoparticle-decorated biochar.
Figure 3. XPS survey scans of biochar and nanoparticle-decorated biochar.
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Figure 4. High-resolution spectra of (a) Ag3d of Biochar@Ag-Cu and Biochar@Ag, (b) Cu2p of Biochar@Ag-Cu and Biochar@Cu, and (c) N1s peak of Biochar and Biochar@Ag-Cu.
Figure 4. High-resolution spectra of (a) Ag3d of Biochar@Ag-Cu and Biochar@Ag, (b) Cu2p of Biochar@Ag-Cu and Biochar@Cu, and (c) N1s peak of Biochar and Biochar@Ag-Cu.
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Figure 5. FESEM images of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
Figure 5. FESEM images of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
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Figure 6. EDX mapping of Biochar@Ag-Cu.
Figure 6. EDX mapping of Biochar@Ag-Cu.
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Figure 7. TEM micrographs (ac) in the bright-field mode of Biochar@Ag-Cu at different resolutions: (d) in the dark field mode on Ag (111) showing the lamellar arrangements, (e) in the bright-field mode of free nanoparticles showing Moire figures, and (f) SAED patterns of nanoparticle assembly.
Figure 7. TEM micrographs (ac) in the bright-field mode of Biochar@Ag-Cu at different resolutions: (d) in the dark field mode on Ag (111) showing the lamellar arrangements, (e) in the bright-field mode of free nanoparticles showing Moire figures, and (f) SAED patterns of nanoparticle assembly.
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Figure 8. Raman spectra of (a) Biochar and (b) Biochar@Ag-Cu.
Figure 8. Raman spectra of (a) Biochar and (b) Biochar@Ag-Cu.
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Figure 9. TGA curve of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
Figure 9. TGA curve of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
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Figure 10. DTG curve of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
Figure 10. DTG curve of (a) Biochar, (b) Biochar@Ag, (c) Biochar@Cu and (d) Biochar@Ag-Cu.
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Figure 11. Mechanism of methyl orange dye mineralization.
Figure 11. Mechanism of methyl orange dye mineralization.
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Figure 12. (a) UV–visible spectrum at different intervals of time: 10 ml of 20 ppm MO + 2 mL H2O2 + 5 mg of Biochar@Ag-Cu, (b) plot of mineralization efficiency, and (c) linear plot of -Ln (CA/C0) vs. time.
Figure 12. (a) UV–visible spectrum at different intervals of time: 10 ml of 20 ppm MO + 2 mL H2O2 + 5 mg of Biochar@Ag-Cu, (b) plot of mineralization efficiency, and (c) linear plot of -Ln (CA/C0) vs. time.
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Figure 13. Colour of MO dye after 0 to 6 h of catalyst treatment in the presence of H2O2.
Figure 13. Colour of MO dye after 0 to 6 h of catalyst treatment in the presence of H2O2.
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Figure 14. UV–vis spectra of MO after treatment with different catalysts.
Figure 14. UV–vis spectra of MO after treatment with different catalysts.
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Figure 15. UV–visible spectra of a mixture of 5 mL of the MO solution (20 ppm, 6.1100 × 10−5 M), 5 mL of the MB solution (20 ppm, 6.2529 × 10−5 M), and 2 mL H2O2 at 0 h and 6 h after treatment with Biochar@Ag-Cu.
Figure 15. UV–visible spectra of a mixture of 5 mL of the MO solution (20 ppm, 6.1100 × 10−5 M), 5 mL of the MB solution (20 ppm, 6.2529 × 10−5 M), and 2 mL H2O2 at 0 h and 6 h after treatment with Biochar@Ag-Cu.
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Table 1. XPS atomic% composition of biochar and nanoparticle-impregnated biochar.
Table 1. XPS atomic% composition of biochar and nanoparticle-impregnated biochar.
Table 2. Comparison of the catalytic performance of composite catalysts for the degradation of methyl orange reported in the literature with the current work.
Table 2. Comparison of the catalytic performance of composite catalysts for the degradation of methyl orange reported in the literature with the current work.
Source of SupportComposite CatalystFabrication
Method and Characteristics of Materials
Light SourceMineralisation
Efficiency (%)
Periodic mesoporous Organo silicateAg-/ZnO-PMOST-80 template assisted, sonication and use of LiAlH4 as reducing agent.Visible lightDegradation = 81%[86]
Walnut shellsAg/TiO2/biocharMixing, calcination, and photo-deposition
(three-step process)
500 W mercury-vapor
(λ = 360 nm)
Walnut shellsTiO2/
Hydrolysis method
(two-step), large particles size due to agglomeration
UV irradiation83.23%[88]
Peanut shellHC/BiOBr/Bi12TiO2Hydrothermal
(use of organic solvent)
7 W-LED (λ range = 380–780 nm)Degradation efficiency = 16.67%[89]
Olive pitB-CA@CuNiWet impregnationDaylightDegradation efficiency = 75%[42]
Potato strawMnFe2O4/chitosan/biocharChemical co-precipitation method (multistep process and time-consuming)Visible LED light/H2O299.50%[90]
Brewer’s spent grainBiochar
(Ag:Cu = 1:1)
Wet impregnation
(One pot)
Daylight/H2O2100%This work
Table 3. % Yield of different biochar samples.
Table 3. % Yield of different biochar samples.
Sample NameWeight before Pyrolysis (g)Weight after Pyrolysis (g)Percentage Yield
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Boubkr, L.; Bhakta, A.K.; Snoussi, Y.; Moreira Da Silva, C.; Michely, L.; Jouini, M.; Ammar, S.; Chehimi, M.M. Highly Active Ag-Cu Nanocrystal Catalyst-Coated Brewer’s Spent Grain Biochar for the Mineralization of Methyl Orange and Methylene Blue Dye Mixture. Catalysts 2022, 12, 1475.

AMA Style

Boubkr L, Bhakta AK, Snoussi Y, Moreira Da Silva C, Michely L, Jouini M, Ammar S, Chehimi MM. Highly Active Ag-Cu Nanocrystal Catalyst-Coated Brewer’s Spent Grain Biochar for the Mineralization of Methyl Orange and Methylene Blue Dye Mixture. Catalysts. 2022; 12(11):1475.

Chicago/Turabian Style

Boubkr, Lahcen, Arvind K. Bhakta, Youssef Snoussi, Cora Moreira Da Silva, Laurent Michely, Mohamed Jouini, Souad Ammar, and Mohamed M. Chehimi. 2022. "Highly Active Ag-Cu Nanocrystal Catalyst-Coated Brewer’s Spent Grain Biochar for the Mineralization of Methyl Orange and Methylene Blue Dye Mixture" Catalysts 12, no. 11: 1475.

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