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28 pages, 10561 KiB

Open AccessFeature PaperArticle

Cd(II) and Pb(II) Adsorption Using a Composite Obtained from Moringa oleifera Lam. Cellulose Nanofibrils Impregnated with Iron Nanoparticles

by Adriana Vázquez-Guerrero, Raúl Cortés-Martínez, Ruth Alfaro-Cuevas-Villanueva, Eric M. Rivera-Muñoz and Rafael Huirache-Acuña

Water 2021, 13(1), 89; https://doi.org/10.3390/w13010089 - 03 Jan 2021

Cited by 32 | Viewed by 4094

Abstract

This work informs on the green synthesis of a novel adsorbent and its adsorption capacity. The adsorbent was synthesized by the combination of iron nanoparticles and cellulose nanofibers (FeNPs/NFCs). Cellulose nanofibers (NFCs) were obtained from Moringa (Moringa oleifera Lam.) by a pulping [...] Read more.

This work informs on the green synthesis of a novel adsorbent and its adsorption capacity. The adsorbent was synthesized by the combination of iron nanoparticles and cellulose nanofibers (FeNPs/NFCs). Cellulose nanofibers (NFCs) were obtained from Moringa (Moringa oleifera Lam.) by a pulping Kraft process, acid hydrolysis, and ultrasonic methods. The adsorption method has advantages such as high heavy metal removal in water treatment. Therefore, cadmium (Cd) and lead (Pb) adsorption with FeNP/NFC from aqueous solutions in batch systems was investigated. The kinetic, isotherm, and thermodynamic parameters, as well as the adsorption capacities of FeNP/NFC in each system at different temperatures, were evaluated. The adsorption kinetic data were fitted to mathematical models, so the pseudo-second-order kinetic model described both Cd and Pb. The kinetic rate constant (K₂), was higher for Cd than for Pb, indicating that the metal adsorption was very fast. The adsorption isotherm data were best described by the Langmuir–Freundlich model for Pb multilayer adsorption. The Langmuir model described Cd monolayer sorption. However, experimental maximum adsorption capacities (q_{e exp}) for Cd (>12 mg/g) were lower than those for Pb (>80 mg/g). In conclusion, iron nanoparticles on the FeNP/NFC composite improved Cd and Pb selectivity during adsorption processes, indicating the process’ spontaneous and exothermic nature. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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15 pages, 1960 KiB

Open AccessArticle

Adsorption by Granular Activated Carbon and Nano Zerovalent Iron from Wastewater: A Study on Removal of Selenomethionine and Selenocysteine

by Stanley Onyinye Okonji, Linlong Yu, John Albino Dominic, David Pernitsky and Gopal Achari

Water 2021, 13(1), 23; https://doi.org/10.3390/w13010023 - 25 Dec 2020

Cited by 13 | Viewed by 2552

Abstract

Selenomethionine (SeMet) and selenocysteine (SeCys) are the most common forms of organic selenium, which is often found in the effluent of industrial wastewater. These organic selenium compounds are toxic, bioavailable and most likely to bioaccumulate in aquatic organisms. This study investigated the use [...] Read more.

Selenomethionine (SeMet) and selenocysteine (SeCys) are the most common forms of organic selenium, which is often found in the effluent of industrial wastewater. These organic selenium compounds are toxic, bioavailable and most likely to bioaccumulate in aquatic organisms. This study investigated the use of two adsorbent candidates (granular activated carbon (GAC) and nano zerovalent iron (nZVI)) as treatment technologies for SeMet and SeCys removal. Batch experiments were performed and inductively coupled plasma optical emission spectrometer (ICP-OES) was used for sample analysis. Experimental data showed GAC demonstrated a higher affinity towards the removal of SeMet and SeCys compared to nZVI. The removal efficiency of SeCys and SeMet by GAC was 96.1% and 86.7%, respectively. NZVI adsorption capacity for SeCys was 39.4% and SeMet < 1.1%. Irrespective of the adsorbent, SeMet is more refractory to be adsorbed compared to SeCys. Kinetics data of GAC and nZVI agreed well with the pseudo-second-order model (R² > 0.990). The experimental data of SeCys was characterized by Langmuir model, indicating monolayer adsorption. The adsorption capacity of nZVI for SeCys increased significantly by about 35%, with a decrease in pH from 9.0 to 4.0, indicating that SeCy removal by nZVI is pH dependent. While electrostatic attraction is considered the driving mechanism for nZVI adsorption, GAC uptake capacity is controlled by weak van der Waal forces. The adsorption of binary adsorbates (SeMet and SeCys) exhibited an inhibitory effect due to the competitive interaction between contaminant molecules. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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12 pages, 2381 KiB

Open AccessArticle

Removal of Diclofenac in Wastewater Using Biosorption and Advanced Oxidation Techniques: Comparative Results

by José M. Angosto, María J. Roca and José A. Fernández-López

Water 2020, 12(12), 3567; https://doi.org/10.3390/w12123567 - 19 Dec 2020

Cited by 25 | Viewed by 4467

Abstract

Wastewater treatment is a topic of primary interest with regard to the environment. Diclofenac is a common analgesic drug often detected in wastewater and surface water. In this paper, three commonly available agrifood waste types (artichoke agrowaste, olive-mill residues, and citrus waste) were [...] Read more.

Wastewater treatment is a topic of primary interest with regard to the environment. Diclofenac is a common analgesic drug often detected in wastewater and surface water. In this paper, three commonly available agrifood waste types (artichoke agrowaste, olive-mill residues, and citrus waste) were reused as sorbents of diclofenac present in aqueous effluents. Citrus-waste biomass for a dose of 2 g·L⁻¹ allowed for removing 99.7% of diclofenac present in the initial sample, with a sorption capacity of 9 mg of adsorbed diclofenac for each gram of used biomass. The respective values obtained for olive-mill residues and artichoke agrowaste were around 4.15 mg·g⁻¹. Advanced oxidation processes with UV/H₂O₂ and UV/HOCl were shown to be effective treatments for the elimination of diclofenac. A significant reduction in chemical oxygen demand (COD; 40–48%) was also achieved with these oxidation treatments. Despite the lesser effectiveness of the sorption process, it should be considered that the reuse and valorization of these lignocellulosic agrifood residues would facilitate the fostering of a circular economy. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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13 pages, 2754 KiB

Open AccessArticle

Removal of Phenolic Compounds from Olive Mill Wastewater by a Polydimethylsiloxane/oxMWCNTs Porous Nanocomposite

by Antonio Turco and Cosimino Malitesta

Water 2020, 12(12), 3471; https://doi.org/10.3390/w12123471 - 10 Dec 2020

Cited by 8 | Viewed by 7147

Abstract

User-friendly and energy-efficient methods able to work in noncontinuous mode for in situ purification of olive mill wastewater (OMW) are necessary. Herein we determined the potential of oxidized multiwalled carbon nanotubes entrapped in a microporous polymeric matrix of polydimethylsiloxane in the removal and [...] Read more.

User-friendly and energy-efficient methods able to work in noncontinuous mode for in situ purification of olive mill wastewater (OMW) are necessary. Herein we determined the potential of oxidized multiwalled carbon nanotubes entrapped in a microporous polymeric matrix of polydimethylsiloxane in the removal and recovery of phenolic compounds (PCs) from OMW. The fabrication of the nanocomposite materials was straightforward and evidenced good adsorption capacity. The adsorption process is influenced by the pH of the OMW. Thermodynamic parameters evidenced the good affinity of the entrapped nanomaterial towards phenols. Furthermore, the kinetics and adsorption isotherms are studied in detail. The presence of oil inside the OMW can speed up the uptake process in batch adsorption experiments with respect to standard aqueous solutions, suggesting a possible use of the nanocomposite for fast processing of OMW directly in the tank where they are stored. Moreover, the prepared nanocomposite is safe and can be easily handled and disposed of, thus avoiding the presence of specialized personnel. After the adsorption process the surface of the nanomaterial can be easily regenerated by mild treatments with diluted acetic acid, thus permitting both the recyclability of the nanomaterial and the recovery of phenolic compounds for a possible use as additives in food and nutraceutical industries and the recovery of OMW for fertirrigation. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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18 pages, 2153 KiB

Open AccessArticle

Uptake and Recovery of Gold from Simulated Hydrometallurgical Liquors by Adsorption on Pine Bark Tannin Resin

by Maria Beatriz Q. L. F. Torrinha, Hugo A. M. Bacelo, Sílvia C. R. Santos, Rui A. R. Boaventura and Cidália M. S. Botelho

Water 2020, 12(12), 3456; https://doi.org/10.3390/w12123456 - 09 Dec 2020

Cited by 12 | Viewed by 2846

Abstract

The recovery of critical and precious metals from waste electrical and electronic equipment (WEEE) is an environmental and economic imperative. Biosorption has been considered a key technology for the selective extraction of gold from hydrometallurgical liquors obtained in the chemical leaching of e-waste. [...] Read more.

The recovery of critical and precious metals from waste electrical and electronic equipment (WEEE) is an environmental and economic imperative. Biosorption has been considered a key technology for the selective extraction of gold from hydrometallurgical liquors obtained in the chemical leaching of e-waste. In this work, the potential of tannin resins prepared from Pinus pinaster bark to sequester and recover gold(III) from hydrochloric acid and aqua regia solutions was assessed. Equilibrium isotherms were experimentally determined and maximum adsorption capacities of 343 ± 38 and 270 ± 19 mg g⁻¹ were found for Au uptake from HCl and HCl/HNO₃ (3:1 v/v) solutions containing 1.0 mol L⁻¹ H⁺. Higher levels of acidity (and chloride ligands) significantly impaired the adsorption of gold from both kinds of leaching solutions, especially in the aqua regia system, in which the adsorbent underperformed. Pseudo-first and pseudo-second order models successfully described the kinetic data. The adsorbent presented high selectivity towards gold. Actually, in simulated aqua regia WEEE liquors, Au(III) was extensively adsorbed, compared to Cu(II), Fe(III), Ni(II), Pd(II), and Zn(II). In three adsorption–desorption cycles, the adsorption capacity of the regenerated adsorbent moderately decreased (19%), although the gold elution in acidic thiourea solution had been quite limited. Future research is needed to examine more closely the elution of gold from the exhausted adsorbents. The results obtained in this work show good perspectives as regards the application of pine bark tannin resins for the selective extraction of Au from electronic waste leach liquors. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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19 pages, 5242 KiB

Open AccessArticle

Mechanistic Study of Pb²⁺ Removal from Aqueous Solutions Using Eggshells

by Mohamed A. Hamouda, Haliemeh Sweidan, Munjed A. Maraqa and Hilal El-Hassan

Water 2020, 12(9), 2517; https://doi.org/10.3390/w12092517 - 09 Sep 2020

Cited by 2 | Viewed by 2702

Abstract

This study investigates the impact of eggshell particle size and solid-to-water (s/w) ratio on lead (Pb²⁺) removal from aqueous solution. Collected raw eggshells were washed, crushed, and sieved into two particle sizes (<150 and 150–500 µm). Batch Pb²⁺ removal experiments [...] Read more.

This study investigates the impact of eggshell particle size and solid-to-water (s/w) ratio on lead (Pb²⁺) removal from aqueous solution. Collected raw eggshells were washed, crushed, and sieved into two particle sizes (<150 and 150–500 µm). Batch Pb²⁺ removal experiments were conducted at different s/w ratios with initial Pb²⁺ concentrations of up to 70 mg/L. The contribution of precipitation to Pb²⁺ removal was simulated by quantifying removal using eggshell water, whereas sorbed Pb²⁺ was quantified by acid digestion. Results indicated that eggshell particle sizes did not affect Pb²⁺ removal. High removal (up to 99%) of Pb²⁺ was achieved for low initial Pb²⁺ concentrations (<30 mg/L) across all s/w ratios studied. However, higher removal capacity was observed at lower s/w ratios. In addition, results confirmed that precipitation played a major role in the removal of Pb²⁺ by eggshells. Yet, this role decreased as the s/w ratio and initial concentration of Pb²⁺ increased. A predictive relationship that relates the normalized removal capacity of eggshells to the s/w ratio was developed to potentially facilitate the design of the reactor. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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13 pages, 2607 KiB

Open AccessArticle

A Biosorption-Pyrolysis Process for Removal of Pb from Aqueous Solution and Subsequent Immobilization of Pb in the Char

by Yue Wang, Jinhong Lü, Dongqing Feng, Sen Guo and Jianfa Li

Water 2020, 12(9), 2381; https://doi.org/10.3390/w12092381 - 25 Aug 2020

Cited by 6 | Viewed by 1990

Abstract

The application of biosorption in the removal of heavy metals from water faces a challenge of safe disposal of contaminated biomass. In this study, a potential solution for this problem was proposed by using a biosorption-pyrolysis process featured by pretreatment of biomass with [...] Read more.

The application of biosorption in the removal of heavy metals from water faces a challenge of safe disposal of contaminated biomass. In this study, a potential solution for this problem was proposed by using a biosorption-pyrolysis process featured by pretreatment of biomass with phosphoric acid (PA). The PA pretreatment of biomass increased the removal efficiency of heavy metal Pb from water by sorption, and subsequent pyrolysis helped immobilize Pb in the residual char. The results indicate that most (>95%) of the Pb adsorbed by the PA-pretreated biomass was retained in the char, and that the lower pyrolysis temperature (350 °C) is more favorable for Pb immobilization. In this way, the bioavailable Pb in the char was hardly detected, while the Pb leachable in acidic solution decreased to <3% of total Pb in the char. However, higher pyrolysis temperature (450 °C) is unfavorable for Pb immobilization, as both the leachable and bioavailable Pb increased to >28%. The reason should be related to the formation of elemental Pb and unstable Pb compounds during pyrolysis at 450 °C, according to the X-ray diffraction study. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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12 pages, 2021 KiB

Open AccessEditor’s ChoiceArticle

Removal of Pb²⁺ from Aqueous Solutions Using K-Type Zeolite Synthesized from Coal Fly Ash

by Yuhei Kobayashi, Fumihiko Ogata, Chalermpong Saenjum, Takehiro Nakamura and Naohito Kawasaki

Water 2020, 12(9), 2375; https://doi.org/10.3390/w12092375 - 24 Aug 2020

Cited by 24 | Viewed by 2539

Abstract

In this study, a novel zeolite (K-type zeolite) was synthesized from coal fly ash (FA), and adsorption capacity on Pb²⁺ was assessed. Six types of zeolite (FA1, FA3, FA6, FA12, FA24, and FA48) were prepared, and their physicochemical properties, such as surface [...] Read more.

In this study, a novel zeolite (K-type zeolite) was synthesized from coal fly ash (FA), and adsorption capacity on Pb²⁺ was assessed. Six types of zeolite (FA1, FA3, FA6, FA12, FA24, and FA48) were prepared, and their physicochemical properties, such as surface functional groups, cation exchange capacity, pH_pzc, specific surface area, and pore volume, were evaluated. The quantity of Pb²⁺ adsorbed by the prepared zeolites followed the order FA < FA1 < FA3 < FA6 < FA12 < FA24 < FA48. Current results indicate that the level of Pb²⁺ adsorbed was strongly related to the surface characteristics of the adsorbent. Additionally, the correlation coefficient between the amounts of Pb²⁺ adsorbed and K⁺ released from FA48 was 0.958. Thus, ion exchange with K⁺ in the interlayer of FA48 is critical for the removal of Pb²⁺ from aqueous media. The new binding energies of Pb(4f) at 135 and 140 eV were detected after adsorption. Moreover, FA48 showed selectivity for Pb²⁺ adsorption in binary solution systems containing cations. The results revealed that FA48 could be useful for removing Pb²⁺ from aqueous media. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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21 pages, 3747 KiB

Open AccessEditor’s ChoiceArticle

Adsorptive Behavior of an Activated Carbon for Bisphenol A Removal in Single and Binary (Bisphenol A—Heavy Metal) Solutions

by M.A. Martín-Lara, M. Calero, A. Ronda, I. Iáñez-Rodríguez and C. Escudero

Water 2020, 12(8), 2150; https://doi.org/10.3390/w12082150 - 30 Jul 2020

Cited by 43 | Viewed by 4435

Abstract

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial [...] Read more.

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial wastewater solutions, testing the reduction of bisphenol A in synthetic solutions by a commercial activated carbon, AC-40, in batch mode. Besides, mixtures of bisphenol A and different heavy metal cations were also studied. So far, no works have reported a complete study about bisphenol A removal by this activated carbon including the use of this material to remove BPA in the presence of metal cations. First, adsorption experiments were performed in batch changing pH, dose of adsorbent, initial bisphenol A concentration and contact time. Results showed greater retention of bisphenol A by increasing the acidity of the medium. Further, the percentage of bisphenol A adsorbed increased with increasing contact time. The selected conditions for the rest of the experiments were pH 5 and a contact time of 48 h. In addition, an increase in retention of bisphenol A when the dose of adsorbent increased was observed. Then, specific experiments were carried out to define the kinetics and the adsorption isotherm. Equilibrium data were adequately fitted to a Langmuir isotherm and the kinetics data fitted well to the pseudo-second-order model. The maximum adsorption capacity provided by Langmuir model was 94.34 mg/g. Finally, the effect of the presence of other heavy metals in water solution on the adsorption of bisphenol A was analyzed. Binary tests revealed competition between the adsorbates and a significant selectivity toward bisphenol A. Finally, the study of the adsorption performance in three consecutive adsorption–desorption cycles showed efficiencies higher than 90% in all cycles, indicating that the activated carbon has good reusability. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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12 pages, 842 KiB

Open AccessArticle

Adsorption Mechanisms and Characteristics of Hg²⁺ Removal by Different Fractions of Biochar

by Xiaoli Guo, Menghong Li, Aijv Liu, Man Jiang, Xiaoyin Niu and Xinpeng Liu

Water 2020, 12(8), 2105; https://doi.org/10.3390/w12082105 - 24 Jul 2020

Cited by 38 | Viewed by 3370

Abstract

The adsorption mechanisms of mercury ion (Hg²⁺) by different fractions of biochar were studied, providing a theoretical basis and practical value for the use of biochar to remediate mercury contamination in water. Biochar (RC) was prepared using corn straw as the [...] Read more.

The adsorption mechanisms of mercury ion (Hg²⁺) by different fractions of biochar were studied, providing a theoretical basis and practical value for the use of biochar to remediate mercury contamination in water. Biochar (RC) was prepared using corn straw as the raw material. It was then fractionated, resulting in inorganic carbon (IC), organic carbon (OC), hydroxyl-blocked carbon (BHC), and carboxyl-blocked carbon (BCC). Before and after Hg²⁺ adsorption, the biochar fractions were characterized by several techniques, such as energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Obtained results indicate that the reaction mechanisms of RC for Hg²⁺ removal mainly include electrostatic adsorption, ion exchange, reduction, precipitation, and complexation. The equilibrium adsorption capacity of RC for Hg²⁺ is 75.56 mg/g, and the adsorption contribution rates of IC and OC are approximately 22.4% and 77.6%, respectively. Despite the lower rate, IC shows the largest adsorption capacity, of 92.63 mg/g. This is attributed to all the mechanisms involved in Hg²⁺ adsorption by IC, with ion exchange being the main reaction mechanism (accounting for 39.8%). The main adsorption mechanism of OC is the complexation of carboxyl and hydroxyl groups with Hg²⁺, accounting for 71.6% of the total OC contribution. BHC and BCC adsorb mercury mainly via the reduction–adsorption mechanism, accounting for 54.6% and 54.5%, respectively. Among all the adsorption mechanisms, the complexation reaction of carboxyl and hydroxyl groups with Hg²⁺ is the dominant effect. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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11 pages, 3160 KiB

Open AccessArticle

Removal of Arsenic(III) Ion from Aqueous Media Using Complex Nickel-Aluminum and Nickel-Aluminum-Zirconium Hydroxides

by Fumihiko Ogata, Noriaki Nagai, Megumu Toda, Masashi Otani, Chalermpong Saenjum, Takehiro Nakamura and Naohito Kawasaki

Water 2020, 12(6), 1697; https://doi.org/10.3390/w12061697 - 14 Jun 2020

Cited by 8 | Viewed by 2360

Abstract

The technology of wastewater treatment involving removal of heavy metals using complex metal hydroxides is reported. In this study, complex nickel-aluminum (NA11 and NA12) and nickel-aluminum-zirconium (NAZ1 and NAZ2) hydroxides were prepared for the removal of arsenite ions, As(III), from aqueous solution. The [...] Read more.

The technology of wastewater treatment involving removal of heavy metals using complex metal hydroxides is reported. In this study, complex nickel-aluminum (NA11 and NA12) and nickel-aluminum-zirconium (NAZ1 and NAZ2) hydroxides were prepared for the removal of arsenite ions, As(III), from aqueous solution. The characteristics of each adsorbent were evaluated, and the adsorption capacity and adsorption mechanism were determined. The adsorption capacity of As(III) on NAZ1 (15.3 mg g⁻¹) was greater than that on NA11 (9.3 mg g⁻¹). Coverage is directly related to the specific surface area with a correlation coefficient of 0.921. Ion exchange involving sulfate ions in the interlayer of the adsorbent also plays a role in the mechanism of As(III) adsorption as demonstrated by correlation coefficients of 0.797 and 0.944 for the NA11 and NAZ1, respectively. The results demonstrate the usefulness of NAZ1 in removing As(III) from aqueous media. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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17 pages, 4164 KiB

Open AccessArticle

Use of Chemically Treated Human Hair Wastes for the Removal of Heavy Metal Ions from Water

by Helan Zhang, Fernando Carrillo-Navarrete, Montserrat López-Mesas and Cristina Palet

Water 2020, 12(5), 1263; https://doi.org/10.3390/w12051263 - 29 Apr 2020

Cited by 17 | Viewed by 6180

Abstract

Human hair is considered a ubiquitous waste product and its accumulation can cause environmental problems. Hence, the search for alternatives that take advantage of this waste as a new raw material is of interest, and contributes to the idea of the circular economy. [...] Read more.

Human hair is considered a ubiquitous waste product and its accumulation can cause environmental problems. Hence, the search for alternatives that take advantage of this waste as a new raw material is of interest, and contributes to the idea of the circular economy. In this study, chemically modified human hair was used as a low cost biosorbent for the removal of heavy metal ions from aqueous solutions. The effect of the contact time, the pH, and the biosorbent concentration on the biosorption process were investigated. Kinetic modeling indicated that the pseudo-second order kinetic equation fitted well with R² > 0.999. Furthermore, the equilibrium data fitted the Langmuir adsorption isotherm at 295 K resulting in saturation concentrations of 9.47 × 10⁻⁵, 5.57 × 10⁻⁵, 3.77 × 10⁻⁵, and 3.61 × 10⁻⁵ mol/g for the sorption of Cr(III), Cu(II), Cd(II), and Pb(II), respectively. The biosorption process did not change the chemical structure and morphology of the hair, which was shown by FTIR and SEM. In addition, desorption experiments prove that 0.1 mol/L EDTA solution is an efficient eluent for the recovery of Pb(II) from the treated human hair. To summarize, treated human hair showed satisfactory biosorption capacity and can be considered as an effective biosorbent for the treatment of water with a low concentration of heavy metal ions. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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13 pages, 1325 KiB

Open AccessArticle

Removal Efficiencies of Manganese and Iron Using Pristine and Phosphoric Acid Pre-Treated Biochars Made from Banana Peels

by Hyunjoon Kim, Ryun-Ah Ko, Sungyun Lee and Kangmin Chon

Water 2020, 12(4), 1173; https://doi.org/10.3390/w12041173 - 20 Apr 2020

Cited by 37 | Viewed by 4207

Abstract

The purpose of this study was to compare the removal efficiencies of manganese (Mn) and iron (Fe) using pristine banana peel biochar (BPB) and phosphoric acid pre-treated biochars (PBPB) derived from banana peels. The removal efficiencies of Mn and Fe were investigated under [...] Read more.

The purpose of this study was to compare the removal efficiencies of manganese (Mn) and iron (Fe) using pristine banana peel biochar (BPB) and phosphoric acid pre-treated biochars (PBPB) derived from banana peels. The removal efficiencies of Mn and Fe were investigated under different adsorbent dosages (0.4–2 g L⁻¹), temperatures (15–45 °C), and ionic strengths (0–0.1 M), and were directly correlated to the differences in physicochemical properties of BPB and PBPB, to identify the removal mechanisms of heavy metals by adsorption processes. The removal of Mn by PBPB obeyed the Freundlich isotherm model while the removal of Mn and Fe by BPB followed the Langmuir isotherm model. However, the removal of Fe by PBPB followed both Freundlich and Langmuir isotherm models. The removal efficiencies of Mn and Fe by BPB and PBPB increased with increasing temperatures and decreased with increasing ionic strengths. PBPB more effectively removed Mn and Fe compared to BPB due to its higher content of oxygen-containing functional groups (O/C ratio of PBPB = 0.45; O/C ratio of BPB = 0.01), higher surface area (PBPB = 27.41 m² g⁻¹; BPB = 11.32 m² g⁻¹), and slightly greater pore volume (PBPB = 0.03 cm³ g⁻¹; BPB = 0.027 cm³ g⁻¹). These observations clearly show that phosphoric acid pre-treatment can improve the physicochemical properties of biochar prepared from banana peels, which is closely related to the removal of heavy metals by adsorption processes. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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17 pages, 6097 KiB

Open AccessArticle

Removal of Aquatic Cadmium Ions Using Thiourea Modified Poplar Biochar

by Yanfeng Zhu, Huageng Liang, Ruilian Yu, Gongren Hu and Fu Chen

Water 2020, 12(4), 1117; https://doi.org/10.3390/w12041117 - 14 Apr 2020

Cited by 23 | Viewed by 3126

Abstract

Removal of aquatic cadmium ions using biochar is a low-cost method, but the results are usually not satisfactory. Modified biochar, which can be a low-cost and efficient material, is urgently required for Cd-polluted water and soil remediation. Herein, poplar bark (SB) and poplar [...] Read more.

Removal of aquatic cadmium ions using biochar is a low-cost method, but the results are usually not satisfactory. Modified biochar, which can be a low-cost and efficient material, is urgently required for Cd-polluted water and soil remediation. Herein, poplar bark (SB) and poplar sawdust (MB) were used as raw materials to prepare modified biochar, which is rich in N- and S- containing groups, i.e., TSBC-600 and TMBC-600, using a co-pyrolysis method with thiourea. The adsorption characteristics of Cd²⁺ in simulated wastewater were explored. The results indicated that the modification optimized the surface structure of biochar, Cd²⁺ adsorption process by both TSBC-600 and TMBC-600 was mainly influenced by the initial pH, biochar dosage, and contact time, sthe TSBC-600 showed a higher adsorption capacity compared to TMBC-600 under different conditions. The Langmuir adsorption isotherm model and pseudo-second-order kinetic model were more consistent with the adsorption behavior of TSBC-600 and TMBC-600 to Cd²⁺, the maximum adsorption capacity of TSBC-600 and TMBC-600 calculated by the Langmuir adsorption isotherm model was 19.998 mg/g and 9.631 mg/g, respectively. The modification method for introducing N and S into biochar by the co-pyrolysis of biomass and thiourea enhanced the removal rate of aquatic cadmium ions by biochar. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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16 pages, 3808 KiB

Open AccessArticle

Upcycling of Electroplating Sludge to Prepare Erdite-Bearing Nanorods for the Adsorption of Heavy Metals from Electroplating Wastewater Effluent

by Yanwen Liu, Asghar Khan, Zhihua Wang, Yu Chen, Suiyi Zhu, Tong Sun, Dongxu Liang and Hongbin Yu

Water 2020, 12(4), 1027; https://doi.org/10.3390/w12041027 - 03 Apr 2020

Cited by 30 | Viewed by 4076

Abstract

Electroplating sludge is a hazardous waste produced in plating and metallurgical processes which is commonly disposed of in safety landfills. In this work, electroplating sludge containing 25.6% Fe and 5.5% Co (named S1) and another containing 36.8% Fe and 7.8% Cr (S2) were [...] Read more.

Electroplating sludge is a hazardous waste produced in plating and metallurgical processes which is commonly disposed of in safety landfills. In this work, electroplating sludge containing 25.6% Fe and 5.5% Co (named S1) and another containing 36.8% Fe and 7.8% Cr (S2) were recycled for the preparation of erdite-bearing particles via a facile hydrothermal route with only the addition of Na₂S·9H₂O. In the sludges, Fe-containing compounds were weakly crystallized and spontaneously converted to short rod-like erdite particles (SP1) in the presence of Co or long nanorod (SP2) particles with a diameter of 100 nm and length of 0.5–1.5 μm in the presence of Cr. The two products, SP1 and SP2, were applied in electroplating wastewater treatment, in which a small portion of Co in SP1 was released in wastewater, whereas Cr in SP2 was not. Adding 0.3 g/L SP2 resulted in the removal of 99.7% of Zn, 99.4% of Cu, 37.9% of Ni and 53.3% of Co in the electroplating wastewater, with residues at concentrations of 0.007, 0.003, 0.33, 0.09 and 0.002 mg/L, respectively. Thus, the treated electroplating wastewater met the discharge standard for electroplating wastewater in China. These removal efficiencies were higher than those achieved using powdered activated carbon, polyaluminum chloride, polyferric sulfate or pure Na₂S·9H₂O reagent. With the method, waste electroplating sludge was recycled as nanorod erdite-bearing particles which showed superior efficiency in electroplating wastewater treatment. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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14 pages, 3201 KiB

Open AccessArticle

Adsorption of Mixed Dye System with Cetyltrimethylammonium Bromide Modified Sepiolite: Characterization, Performance, Kinetics and Thermodynamics

by Jian Yu, Aiyi Zou, Wenting He and Bin Liu

Water 2020, 12(4), 981; https://doi.org/10.3390/w12040981 - 30 Mar 2020

Cited by 16 | Viewed by 2634

Abstract

In this study, sepiolite was modified by calcination (200 °C) and cetyltrimethylammonium bromide (CTMAB) treatment. Though the specific surface area sharply declined, the adsorption amount of Acid Orange II (AO), Reactive Blue (RB), Acid Fuchsin (AR) and their mixed solution were improved. The [...] Read more.

In this study, sepiolite was modified by calcination (200 °C) and cetyltrimethylammonium bromide (CTMAB) treatment. Though the specific surface area sharply declined, the adsorption amount of Acid Orange II (AO), Reactive Blue (RB), Acid Fuchsin (AR) and their mixed solution were improved. The morphology of modified sepiolite showed a better dispersibility and looser structure. The adsorption performance was highly impacted by the pH condition and adsorbent dosage. The electrostatic attraction of positively charged adsorption sites on the adsorbent surface and the negatively charged anionic dye could enhance the adsorption amount especially under acid condition. The order of preferentially adsorbed dye was AO > RB > AR. The adsorption process was much correlated to the quasi-second-order reaction kinetics. The adsorption amount and equilibrium amount of single dye system, as well as in the mixed system were in accordance with the Langmuir model and extended Langmuir isotherm. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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19 pages, 3701 KiB

Open AccessEditor’s ChoiceArticle

Adsorption of Methylene Blue in Water onto Activated Carbon by Surfactant Modification

by Yu Kuang, Xiaoping Zhang and Shaoqi Zhou

Water 2020, 12(2), 587; https://doi.org/10.3390/w12020587 - 21 Feb 2020

Cited by 332 | Viewed by 18119

Abstract

In this paper, the enhanced adsorption of methylene blue (MB) dye ion on the activated carbon (AC) modified by three surfactants in aqueous solution was researched. Anionic surfactants—sodium lauryl sulfate (SLS) and sodium dodecyl sulfonate (SDS)—and cationic surfactant—hexadecyl trimethyl ammonium bromide (CTAB)—were used [...] Read more.

In this paper, the enhanced adsorption of methylene blue (MB) dye ion on the activated carbon (AC) modified by three surfactants in aqueous solution was researched. Anionic surfactants—sodium lauryl sulfate (SLS) and sodium dodecyl sulfonate (SDS)—and cationic surfactant—hexadecyl trimethyl ammonium bromide (CTAB)—were used for the modification of AC. This work showed that the adsorption performance of cationic dye by activated carbon modified by anionic surfactants (SLS) was significantly improved, whereas the adsorption performance of cationic dye by activated carbon modified by cationic surfactant (CTAB) was reduced. In addition, the effects of initial MB concentration, AC dosage, pH, reaction time, temperature, real water samples, and additive salts on the adsorption were studied. When Na⁺, K⁺, Ca²⁺, NH⁴⁺, and Mg²⁺ were present in the MB dye solution, the effect of these cations was negligible on the adsorption (<5%). The presence of NO^2- improved the adsorption performance significantly, whereas the removal rate of MB was reduced in the presence of competitive cation (Fe²⁺). It was found that the isotherm data had a good correlation with the Langmuir isotherm through analyzing the experimental data by various models. The dynamics of adsorption were better described by the pseudo-second-order model and the adsorption process was endothermic and spontaneous. The results showed that AC modified by anionic surfactant was effective for the adsorption of MB dye in both modeling water and real water. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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27 pages, 1127 KiB

Open AccessEditor’s ChoiceReview

Biochar as an Eco-Friendly and Economical Adsorbent for the Removal of Colorants (Dyes) from Aqueous Environment: A Review

by Prithvi Srivatsav, Bhaskar Sriharsha Bhargav, Vignesh Shanmugasundaram, Jayaseelan Arun, Kannappan Panchamoorthy Gopinath and Amit Bhatnagar

Water 2020, 12(12), 3561; https://doi.org/10.3390/w12123561 - 18 Dec 2020

Cited by 135 | Viewed by 13062

Abstract

Dyes (colorants) are used in many industrial applications, and effluents of several industries contain toxic dyes. Dyes exhibit toxicity to humans, aquatic organisms, and the environment. Therefore, dyes containing wastewater must be properly treated before discharging to the surrounding water bodies. Among several [...] Read more.

Dyes (colorants) are used in many industrial applications, and effluents of several industries contain toxic dyes. Dyes exhibit toxicity to humans, aquatic organisms, and the environment. Therefore, dyes containing wastewater must be properly treated before discharging to the surrounding water bodies. Among several water treatment technologies, adsorption is the most preferred technique to sequester dyes from water bodies. Many studies have reported the removal of dyes from wastewater using biochar produced from different biomass, e.g., algae and plant biomass, forest, and domestic residues, animal waste, sewage sludge, etc. The aim of this review is to provide an overview of the application of biochar as an eco-friendly and economical adsorbent to remove toxic colorants (dyes) from the aqueous environment. This review highlights the routes of biochar production, such as hydrothermal carbonization, pyrolysis, and hydrothermal liquefaction. Biochar as an adsorbent possesses numerous advantages, such as being eco-friendly, low-cost, and easy to use; various precursors are available in abundance to be converted into biochar, it also has recyclability potential and higher adsorption capacity than other conventional adsorbents. From the literature review, it is clear that biochar is a vital candidate for removal of dyes from wastewater with adsorption capacity of above 80%. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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40 pages, 6346 KiB

Open AccessEditor’s ChoiceReview

An Overview and Evaluation of Highly Porous Adsorbent Materials for Polycyclic Aromatic Hydrocarbons and Phenols Removal from Wastewater

by Zakariyya Uba Zango, Nonni Soraya Sambudi, Khairulazhar Jumbri, Anita Ramli, Noor Hana Hanif Abu Bakar, Bahruddin Saad, Muhammad Nur’ Hafiz Rozaini, Hamza Ahmad Isiyaka, Abubaker Mohammed Osman and Abdelmoneim Sulieman

Water 2020, 12(10), 2921; https://doi.org/10.3390/w12102921 - 19 Oct 2020

Cited by 60 | Viewed by 6237

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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19 pages, 1909 KiB

Open AccessReview

The Use of Biochar and Pyrolysed Materials to Improve Water Quality through Microcystin Sorption Separation

by Vladimír Frišták, H. Dail Laughinghouse IV and Stephen M. Bell

Water 2020, 12(10), 2871; https://doi.org/10.3390/w12102871 - 15 Oct 2020

Cited by 12 | Viewed by 3158

Abstract

Harmful algal blooms have increased globally with warming of aquatic environments and increased eutrophication. Proliferation of cyanobacteria (blue-green algae) and the subsequent flux of toxic extracellular microcystins present threats to public and ecosystem health and challenges for remediation and management. Although methods exist, [...] Read more.

Harmful algal blooms have increased globally with warming of aquatic environments and increased eutrophication. Proliferation of cyanobacteria (blue-green algae) and the subsequent flux of toxic extracellular microcystins present threats to public and ecosystem health and challenges for remediation and management. Although methods exist, there is currently a need for more environmentally friendly and economically and technologically feasible sorbents. Biochar has been proposed in this regard because of its high porosity, chemical stability, and notable sorption efficiency for removing of cyanotoxins. In light of worsening cyanobacterial blooms and recent research advances, this review provides a timely assessment of microcystin removal strategies focusing on the most pertinent chemical and physical sorbent properties responsible for effective removal of various pollutants from wastewater, liquid wastes, and aqueous solutions. The pyrolysis process is then evaluated for the first time as a method for sorbent production for microcystin removal, considering the suitability and sorption efficiencies of pyrolysed materials and biochar. Inefficiencies and high costs of conventional methods can be avoided through the use of pyrolysis. The significant potential of biochar for microcystin removal is determined by feedstock type, pyrolysis conditions, and the physiochemical properties produced. This review informs future research and development of pyrolysed materials for the treatment of microcystin contaminated aquatic environments. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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32 pages, 2758 KiB

Open AccessEditor’s ChoiceReview

Chemically Modified Biosorbents and Their Role in the Removal of Emerging Pharmaceutical Waste in the Water System

by Adewale Adewuyi

Water 2020, 12(6), 1551; https://doi.org/10.3390/w12061551 - 29 May 2020

Cited by 102 | Viewed by 10825

Abstract

Presence of pharmaceutically active compounds (PACs) as emerging contaminants in water is a major concern. Recent reports have confirmed the presence of PACs in natural and wastewater systems, which have caused several problems indicating the urgent need for their removal. The current review [...] Read more.

Presence of pharmaceutically active compounds (PACs) as emerging contaminants in water is a major concern. Recent reports have confirmed the presence of PACs in natural and wastewater systems, which have caused several problems indicating the urgent need for their removal. The current review evaluates the role of chemically modified biosorbents in the removal of PACs in water. Reported biosorbents include plant and animal solid waste, microorganisms and bio-composite. Bio-composites exhibited better prospects when compared with other biosorbents. Types of chemical treatment reported include acid, alkaline, solvent extraction, metal salt impregnation and surface grafting, with alkaline treatment exhibiting better results when compared with other treatments. The biosorption processes mostly obeyed the pseudo-second-order model and the Langmuir isotherm model in a process described mainly by ionic interaction. Desorption and regeneration capacity are very important in selecting an appropriate biosorbent for the biosorption process. Depending on the type of biosorbent, the cost of water treatment per million liters of water was estimated as US $10–US $200, which presents biosorption as a cheap process compared to other known water treatment processes. However, there is a need to conduct large-scale studies on the biosorption process for removing PACs in water. Full article

(This article belongs to the Special Issue Adsorbents for Water and Wastewater Treatment and Resource Recovery)

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