Research

17 pages, 1983 KiB

Open AccessArticle

Removal of Heavy Metal Ions from Wastewaters: An Application of Sodium Trithiocarbonate and Wastewater Toxicity Assessment

by Maciej Thomas, Violetta Kozik, Andrzej Bąk, Krzysztof Barbusiński, Joanna Jazowiecka-Rakus and Josef Jampilek

Materials 2021, 14(3), 655; https://doi.org/10.3390/ma14030655 - 31 Jan 2021

Cited by 19 | Viewed by 2493

Abstract

The synthesis and application of sodium trithiocarbonate (Na₂CS₃) for the treatment of real galvanic wastewater in order to remove heavy metals (Cu, Cd and Zn) was investigated. A Central Composite Design/Response Surface Methodology (CCD/RSM) was employed to optimize the [...] Read more.

The synthesis and application of sodium trithiocarbonate (Na₂CS₃) for the treatment of real galvanic wastewater in order to remove heavy metals (Cu, Cd and Zn) was investigated. A Central Composite Design/Response Surface Methodology (CCD/RSM) was employed to optimize the removal of heavy metals from industrial wastewater. Adequacy of approximated data was verified using Analysis of Variance (ANOVA). The calculated coefficients of determination (R² and R²_adj) were 0.9119 and 0.8532, respectively. Application of Na₂CS₃ conjugated with CCD/RSM allowed Cu, Cd and Zn levels to be decreased and, as a consequence, ∑_Cu,Cd,Zn decreased by 99.80%, 97.78%, 99.78%, and 99.69%, respectively, by using Na₂CS₃ at 533 mg/L and pH 9.7, within 23 min. Implementation of conventional metal precipitation reagents (NaOH, Ca(OH)₂ and CaO) at pH 11 within 23 min only decreased ∑_Cu,Cd,Zn by 90.84%, 93.97% and 93.71%, respectively. Rotifer Brachionus plicatilis was used to conduct the assessment of wastewater toxicity. Following the application of Na₂CS₃, after 60 min the mortality of B. plicatilis was reduced from 90% to 25%. Engagement of Na₂CS₃ under optimal conditions caused the precipitation of heavy metals from the polluted wastewater and significantly decreased wastewater toxicity. In summary, Na₂CS₃ can be used as an effective heavy metal precipitating agent, especially for Cu, Cd and Zn. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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16 pages, 2400 KiB

Open AccessArticle

Potassium Ferrate (VI) as the Multifunctional Agent in the Treatment of Landfill Leachate

by Maciej Thomas, Violetta Kozik, Krzysztof Barbusiński, Aleksander Sochanik, Josef Jampilek and Andrzej Bąk

Materials 2020, 13(21), 5017; https://doi.org/10.3390/ma13215017 - 06 Nov 2020

Cited by 10 | Viewed by 2376

Abstract

Possible use of potassium ferrate (VI) (K₂FeO₄) for the treatment of landfill leachate (pH = 8.9, Chemical Oxygen Demand (COD) 770 mg O₂/L, Total Organic Carbon (TOC) 230 mg/L, Total Nitrogen (Total N) 120 mg/L, Total Phosphorus [...] Read more.

Possible use of potassium ferrate (VI) (K₂FeO₄) for the treatment of landfill leachate (pH = 8.9, Chemical Oxygen Demand (COD) 770 mg O₂/L, Total Organic Carbon (TOC) 230 mg/L, Total Nitrogen (Total N) 120 mg/L, Total Phosphorus (Total P) 12 mg/L, Total Coli Count (TCC) 6.8 log CFU/mL (Colony-Forming Unit/mL), Most Probable Number (MPN) of fecal enterococci 4.0 log/100 mL, Total Proteolytic Count (TPC) 4.4 log CFU/mL) to remove COD was investigated. Central Composite Design (CCD) and Response Surface Methodology (RSM) were applied for modelling and optimizing the purification process. Conformity of experimental and predicted data (R² = 0.8477, R_adj² = 0.7462) were verified using Analysis of Variance (ANOVA). Application of K₂FeO₄ using CCD/RSM allowed to decrease COD, TOC, Total N, Total P, TCC, MPN of fecal enterococci and TPC by 76.2%, 82.6%, 68.3%, 91.6%, 99.0%, 95.8% and 99.3%, respectively, by using K₂FeO₄ 0.390 g/L, at pH = 2.3 within 25 min. Application of equivalent amount of iron (as FeSO₄ × 7H₂O and FeCl₃ × 6H₂O) under the same conditions allowed to diminish COD, TOC, Total N, Total P, TCC, MPN of fecal enterococci and TPC only by 38.1%, 37.0%, 20.8%, 95.8%, 94.4%, 58.2%, 90.8% and 41.6%, 45.7%, 29.2%, 95.8%, 92.1%, 58.2%, 90.0%, respectively. Thus, K₂FeO₄ could be applied as an environmentally friendly reagent for landfill leachate treatment. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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12 pages, 2895 KiB

Open AccessArticle

Ag₂O and NiO Decorated CuFe₂O₄ with Enhanced Photocatalytic Performance to Improve the Degradation Efficiency of Methylene Blue

by Lu Liu, Nan Hu, Yonglei An, Xingyuan Du, Xiao Zhang, Yan Li, Yan Zeng and Zheng Cui

Materials 2020, 13(21), 4760; https://doi.org/10.3390/ma13214760 - 25 Oct 2020

Cited by 14 | Viewed by 2156

Abstract

Dye wastewater is a serious threat to human health and life. It is an important task for researchers to treat it efficiently. Among many treatment methods, the photo-Fenton method can rapidly degrade organic pollutants. In this study, a ternary photocatalyst, Ag₂O-NiO/CuFe [...] Read more.

Dye wastewater is a serious threat to human health and life. It is an important task for researchers to treat it efficiently. Among many treatment methods, the photo-Fenton method can rapidly degrade organic pollutants. In this study, a ternary photocatalyst, Ag₂O-NiO/CuFe₂O₄, was prepared and applied for a photo-Fenton reaction to degrade methylene blue (MB). MB had the best degradation effect when 10 mg of the catalyst were used in an 80 mL reaction system for measurement. The degradation rate of MB was up to 96.67% in 60 min with a high degradation rate constant

k = 5.67 {\times 10}^{- 2} \min^{- 1}

. The total organic carbon (TOC) degradation rate was 78.64% with a TOC degradation rate constant of

k = 2.57 {\times 10}^{- 2} \min^{- 1}

. Therefore, this study fully proves that Ag₂O-NiO/CuFe₂O₄ can catalyze the photo-Fenton reaction and effectively degrade MB. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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19 pages, 3573 KiB

Open AccessArticle

Hydrogen Production through Glycerol Photoreforming on TiO₂/Mesoporous Carbon: Influence of the Synthetic Method

by Juan Carlos Escamilla, Jesús Hidalgo-Carrillo, Juan Martín-Gómez, Rafael C. Estévez-Toledano, Vicente Montes, Daniel Cosano, Francisco J. Urbano and Alberto Marinas

Materials 2020, 13(17), 3800; https://doi.org/10.3390/ma13173800 - 28 Aug 2020

Cited by 9 | Viewed by 2470

Abstract

This article explores the effect of the synthetic method of titanium dioxide (TiO₂)/C composites (physical mixture and the water-assisted/unassisted sol-gel method) on their photocatalytic activity for hydrogen production through glycerol photoreforming. The article demonstrates that, apart from a high surface area [...] Read more.

This article explores the effect of the synthetic method of titanium dioxide (TiO₂)/C composites (physical mixture and the water-assisted/unassisted sol-gel method) on their photocatalytic activity for hydrogen production through glycerol photoreforming. The article demonstrates that, apart from a high surface area of carbon and the previous activation of its surface to favor titania incorporation, the appropriate control of titania formation is crucial. In this sense, even though the amount of incorporated titania was limited by the saturation of carbon surface groups (in our case, ca. 10 wt.% TiO₂), the sol-gel process without water addition seemed to be the best method, ensuring the formation of small homogeneously-distributed anatase crystals on mesoporous carbon. In this way, a ca. 110-fold increase in catalyst activity compared to Evonik P25 (expressed as hydrogen micromole per grams of titania) was achieved. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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16 pages, 4979 KiB

Open AccessArticle

Microwave-Assisted Glycerol Etherification Over Sulfonic Acid Catalysts

by Laura Aguado-Deblas, Rafael Estevez, Marco Russo, Valeria La Parola, Felipa M. Bautista and Maria Luisa Testa

Materials 2020, 13(7), 1584; https://doi.org/10.3390/ma13071584 - 30 Mar 2020

Cited by 18 | Viewed by 2886

Abstract

Glycerol is the main by-product of biodiesel production. For this reason, its valorization into value-added products, by using green procedures, represents an important goal. Different sulfonic acid silica- or titania-based catalysts were prepared, characterized and tested in the glycerol etherification process, assisted by [...] Read more.

Glycerol is the main by-product of biodiesel production. For this reason, its valorization into value-added products, by using green procedures, represents an important goal. Different sulfonic acid silica- or titania-based catalysts were prepared, characterized and tested in the glycerol etherification process, assisted by microwaves, in order to obtain biodiesel additives. The surface and structural properties of the catalysts were investigated by means of N₂ adsorption isotherms, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements by X-Ray Fluorescence Spectroscopy (XRF). The best performance in terms of activity was achieved in the presence of the sulfonic function directly linked to the amorphous silica. By the correlation of the structure properties of the materials and their activity, the performance of the catalysts was shown to be influenced mainly by the surface area, pore volume and acidity. Recycling experiments performed over the most active systems showed that the sulfonic silica-based materials maintained their performance during several cycles. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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12 pages, 2990 KiB

Open AccessArticle

Dehydration of Fructose to 5-HMF over Acidic TiO₂ Catalysts

by Maria Luisa Testa, Gianmarco Miroddi, Marco Russo, Valeria La Parola and Giuseppe Marcì

Materials 2020, 13(5), 1178; https://doi.org/10.3390/ma13051178 - 06 Mar 2020

Cited by 31 | Viewed by 3398

Abstract

Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated [...] Read more.

Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated by means of X-ray diffraction (XRD), N₂ adsorption isotherms, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements. Special attention was focused on the reaction conditions, both in terms of 5-HMF selectivity and the sustainability of the process, choosing water as the solvent. Among the various process condition studied, TiO₂-SO₃H catalyzed a complete conversion (99%) of 1.1M fructose and 5-HMF selectivity (50%) and yield (50%) at 165 °C. An important improvement of the HMF selectivity (71%) was achieved when the reaction was carried out by using a lower fructose concentration (0.1M) and lower temperature (140 °C). The catalytic activities of the materials were related to their acid capacities as much as their textural properties. In particular, a counterbalance between the acidity and the structure of the pores in which the catalytic sites are located, results in the key issue for switch the selectivity towards the achievement of 5-HMF. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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10 pages, 1877 KiB

Open AccessArticle

Mesoporous Acidic Catalysts Synthesis from Dual-Stage and Rising Co-Current Gasification Char: Application for FAME Production from Waste Cooking Oil

by Junaid Ahmad, Umer Rashid, Francesco Patuzzi, Nahla Alamoodi, Thomas Shean Yaw Choong, Soroush Soltani, Chawalit Ngamcharussrivichai, Imededdine Arbi Nehdi and Marco Baratieri

Materials 2020, 13(4), 871; https://doi.org/10.3390/ma13040871 - 15 Feb 2020

Cited by 3 | Viewed by 1962

Abstract

The main purpose of this work is to investigate the application options of the char produced from gasification plants. Two promising mesoporous acidic catalysts were synthesized using char as a support material. Two char samples were collected from either a dual-stage or a [...] Read more.

The main purpose of this work is to investigate the application options of the char produced from gasification plants. Two promising mesoporous acidic catalysts were synthesized using char as a support material. Two char samples were collected from either a dual-stage or a rising co-current biomass gasification plant. The catalysts produced from both gasification char samples were characterized for their physiochemical and morphological properties using N₂ physorption measurement, total acidity evaluation through TPD-NH₃, functional groups analysis by FT-IR, and morphology determination via FESEM. Results revealed that the dual-stage char-derived mesoporous catalyst (DSC-SO₄) with higher specific surface area and acidic properties provided higher catalytic activity for fatty acid methyl esters (FAME) production from waste cooking oil (WCO) than the mesoporous catalyst obtained from char produced by rising co-current gasification (RCC-SO₄). Furthermore, the effects of methanol/oil molar ratio (3:1–15:1), catalyst concentration (1–5 wt.% of oil), and reaction time (30–150 min) were studied while keeping the transesterification temperature constant at 65 °C. The optimal reaction conditions for the transesterification of WCO were 4 wt.% catalyst concentration, 12:1 methanol/oil molar ratio, and 90 min operating time. The optimized reaction conditions resulted in FAME conversions of 97% and 83% over DSC-SO₄ and RCC-SO₄ catalysts, respectively. The char-based catalysts show excellent reusability, since they could be reused six times without any modification. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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16 pages, 3998 KiB

Open AccessArticle

Single-Pot Synthesis of Biodiesel using Efficient Sulfonated-Derived Tea Waste-Heterogeneous Catalyst

by Umer Rashid, Junaid Ahmad, Mohd Lokman Ibrahim, Jan Nisar, Muhammad Asif Hanif and Thomas Yaw Choong Shean

Materials 2019, 12(14), 2293; https://doi.org/10.3390/ma12142293 - 18 Jul 2019

Cited by 37 | Viewed by 3648

Abstract

The main purpose of this manuscript is to report the new usage of tea waste (TW) as a catalyst for efficient conversion of palm fatty acid distillate (PFAD) to biodiesel. In this work, we investigate the potential of tea waste char as a [...] Read more.

The main purpose of this manuscript is to report the new usage of tea waste (TW) as a catalyst for efficient conversion of palm fatty acid distillate (PFAD) to biodiesel. In this work, we investigate the potential of tea waste char as a catalyst for biodiesel production before and after sulfonation. The activated sulfonated tea waste char catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), elemental composition (CHNS), nitrogen adsorption-desorption using Brunauer-Emmett-Teller (BET) and ammonia-temperature-programmed desorption (NH₃-TPD). The activated tea waste char catalyst shows higher acid density of 31 μmol g⁻¹ as compared to tea waste char of 16 μmol g⁻¹ and higher surface area of 122 m²/g. The optimum fatty acid conversion conditions were found that 4 wt % of catalyst loading with 9:1 of methanol:PFAD for 90 min of reaction time at 65 °C gives 97% free fatty acid (FFA) conversion. In conclusion, the sulfonated tea waste (STW) catalyst showed an impressive catalytic activity towards the esterification of PFAD at optimum reaction conditions with significant recyclability in five successive cycles without any reactivation step. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Energy and Environmental Applications)

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