Systematic optimization of biochars derived from corn wastes, pineapple leaf, and sugarcane bagasse for Cu(II) adsorption through response surface methodology.

Many industrial wastewaters contain an appreciable amount of toxic copper (Cu(II)) that needs to be properly treated before discharging into receiving water body. Adsorption can effectively remove Cu(II) with optimized parameters. This study investigates the critical pyrolysis parameters of biochar derived from agricultural waste. Optimized biochar showed maximum Cu(II) adsorption capacity of 60.7, 36.8, and 35.5 mg g-1 by PLB, SBB, and CWB at pyrolysis temperatures of 555 ℃, 559 ℃, 507 ℃, respectively, compared with commercial activated carbon (CAC, 40.8 mg g-1). Surface characterization confirmed surface complexation, electrostatic interaction, and cation exchange capacity as Cu(II) removal mechanisms. The presence of humic acid reduced the Cu(II) removal of both CAC and optimized biochars. Optimized PLB displayed high reusability (87% Cu(II) removal efficiency) after five consecutive cycles using pressure cooker regeneration. With excellent Cu(II) adsorption capacity and reusability, the investigated biochars show high applicability potential to Cu(II)-laden wastewater treatment.

Highly efficient LaMO3 (M = Co, Fe) perovskites catalyzed Fenton's reaction for degradation of direct blue 86.

Perovskite-structured catalysts LaMO3 (M = Co, Fe) were successfully synthesized and attempted to catalyze hydrogen peroxide (H2O2) for the degradation of Direct Blue 86 (DB86), a carcinogenic phthalocyanine dye. The heterogeneous Fenton-like reaction revealed that the oxidative power of the LaCoO3-catalyzed H2O2 (LaCoO3/H2O2) process was higher than that of LaFeO3/H2O2. When LaCoO3 was calcined at 750 °C for 5 h, 100 mg/L of DB86 could be completely degraded within 5 min via LaCoO3/H2O2 system under H2O2 0.0979 mol/L, initial pH 3.0, LaCoO3 0.4 g/L, and 25 °C. The oxidative LaCoO3/H2O2 system has a low activation energy (14.68 kJ/mol) for DB86 degradation, indicating that it is a fast reaction process with highly favorable at high reaction temperatures. For the first time, a cyclic reaction mechanism of catalytic LaCoO3/H2O2 system was proposed based on the evidence of coexisting CoII and CoIII on the LaCoO3 surface and the presence of HO• radicals (major), O2•- radicals (minor), and 1O2 (minor). LaCoO3 perovskite catalyst was reusable and still maintained reactive with a satisfactory degradation efficiency within 5 min even after five consecutive uses. This study shows that the as-prepared LaCoO3 is a highly efficient catalyst for phthalocyanine dye degradation.

Novel biomass-derived porous-graphitic carbon coated iron oxide nanocomposite as an efficient electrocatalyst for the sensitive detection of rutin (vitamin P) in food and environmental samples.

Design and development of inexpensive, portable, and eco-friendly electrochemical non-enzymatic sensors with high selectivity and sensitivity is pivotal in analytical chemistry. In this regard, we have developed a highly porous graphitic-activated carbon (GAC, derived from tamarind fruit shell biomass) coated iron oxide (Fe2O3) nanocomposite (Fe2O3/GAC) for the efficient detection of rutin (vitamin p). Fe2O3/GAC nanocomposite was prepared using a facile green synthesis method and thoroughly characterized using SEM, XRD, and XPS techniques. As-prepared Fe2O3/GAC nanocomposite was deposited over a screen printed electrode (SPE) to fabricate Fe2O3/GAC/SPE and utilized as a non-enzymatic sensor for the electrochemical determination of rutin in food and environmental samples. The modified electrode was characterized using cyclic voltammetry and electrochemical impedance spectroscopy techniques, which witnessed the excellent conductivity of the developed sensor. The fabricated Fe2O3/GAC/SPE nanocomposite exhibited a set of redox peaks in the presence of rutin, corresponding to the electrochemical redox feature of rutin (rutin to 3',4'-diquinone). Further, the modified electrode displayed excellent electrocatalytic characteristics towards the oxidation of rutin, based on which a differential pulse voltammetry-based sensor was developed for rutin determination. The developed non-enzymatic sensor has shown prominent performance towards rutin detection in a wide linear range from 0.1 to 130 µM with an excellent detection limit of 0.027 µM. The enhanced electrocatalytic response could be ascribed to the synergistic effect of Fe2O3 and GAC on the developed probe. Moreover, the developed sensor was successfully utilized for real-time detection of rutin in various samples.

Adsorption of metal on pineapple leaf biochar: Key affecting factors, mechanism identification, and regeneration evaluation.

Although tremendous works have been done on metal adsorption via biochar, mechanisms responsible for metal adsorption remain uncertain. This is the first work that provides direct evidence on the identification of Ni(II), Zn(II), and Cu(II) adsorption mechanisms on pineapple leaf biochar (PLB) using surface characteristics analyses, including X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscope (FTIR), and scanning electron microscope with energy-dispersive X-ray spectroscope (SEM-EDS). From Langmuir isotherm fitting, the maximum adsorption capacity of PLB for Ni(II), Zn(II), and Cu(II) are 44.88, 46.00, and 53.14 mg g-1, respectively, surpassing all biochars reported in the literature. Findings of surface characterization techniques coupled with cation released during adsorption, cation exchange, and surface complexation mechanisms were proposed. PLB is reusable and remains sufficient adsorption capacity even six consecutive cycles via pressure cooker regeneration. With high regenerability and ultrahigh adsorption capacity, PLB defines itself as a promising adsorbent for future applications in metal-laden wastewater.

Environmental concerns and pollution control in the context of developing countries.

INTRODUCTION: In the developing countries, the pace of change-in vital technologies, in scientific research, in economic fundamentals, in the living environment, and in pursuing quality of life-is accelerating every day, propelled by continuous changes in technology innovation, human activities, and the rapidly evolving demands of the COVID-19 pandemic. This special issue (SI) of Environmental Science and Pollution Research (ESPR) collected 17 peer-reviewed articles relating to green buildings research, the impact of climate change on the extreme weather events, forward osmosis membranes for water reuse, the impacts of human activities to fragile water environments and economy, air pollution control and carbon emission reduction, risk assessment of pollution hazard and water resources, adsorption reaction of antibiotic pollution in subsurface, synthesized novel adsorptive materials in response to nitrogen and phosphorus, dye, and toluene pollution. All selected papers were relevance to the theme of this SI and formally presented at the 2020 5th International Conference on Advances in Energy and Environment Research (ICAEER 2020) on September 18th-20th, 2020, Shanghai, China. For the safety of the participants, ICAEER 2020 was held via online presentation because of the coronavirus pandemic sweeping across all over the world. As an annually held conference, the upcoming 6th ICAEER 2021 is scheduled held in Shanghai from September 10 to 12, 2021 ( http://www.icaeer.org/index.html ). The guest editor (GE) of this SI welcomes you all to participate in this conference.

Hexachloroethane dechlorination in sulfide-containing aqueous solutions catalyzed by nitrogen-doped carbon materials.

This study demonstrated that nitrogen-doped carbon materials (NCMs) could effectively catalyze the chlorine elimination process in hexachloroethane (HCA) declorination in sulfide-containing environments for the first time. The kobs values of HCA dechlorination by sulfide in the presence of 10 mg/L NCMs were higher than that of no mediator at pH 7.3 by one or two orders of magnitude. The catalytic capabilities of NCMs on HCA dechlorination were evident in common ranges of natural pH (5.3-8.9) and it could be accelerated by the increase of pH but be suppressed by the presence of dissolved humic acid. Moreover, NCMs exhibited much better catalytic capability on HCA dechlorination compared to the carbon materials, mainly owing to the combined contributions of pyridine N, including enhanced nucleophilic attack to HCA molecule by generating newborn C-S-S and activation of HCA molecule by elongating C-Cl bonds. The functions of pyridine N in micron-sized NCMs with mesopores were better than in nano-sized NCMs on HCA dechlorination. These findings displayed the potential of NCMs, when released into sulfide-containing environments, may significantly increase the dechlorination of chlorinated aliphatic hydrocarbons.

Kinetic study and performance comparison of TiO2-mediated visible-light-responsive photocatalysts for the inactivation of Aspergillus niger.

Fungi are highly survived with exceptional resistance to environmental stress. Conventional fungicides are quite efficient, but the increase in use raises severe environmental problems. In this study, environmentally friendly TiO2-mediated visible-light-responsive photocatalysts, namely N-TiO2, N-T-TiO2, C-TiO2, and Pd-C-TiO2, were used to compare the performance of disinfecting a mold fungi Aspergillus niger. Key parameters, including photocatalyst dosage, the initial fungal concentration, and visible-light intensity, affecting the disinfecting process, was investigated. A new developed Light-responsive Modified Hom's (LMH) kinetic model incorporating visible-light intensity and photocatalyst light-absorption coefficient was firstly used to predict such photocatalytic process in fungal inactivation. Among the photocatalysts, Pd-C-TiO2 showed the highest inactivation performance against fungi, followed by C-TiO2, N-T-TiO2, and N-TiO2. In general, inactivation increased with increasing photocatalyst dosage and light intensity while decreased with increasing initial fungal concentration. For kinetic modeling, the LMH model supports the hypothesis that photocatalyst performance toward visible-light-driven fungal inactivation primarily depends on the light-absorption capacity of the photocatalyst. In conclusion, mold fungi Aspergillus niger are effectively disinfected by TiO2-mediated visible-light-responsive photocatalysts, and such fungal inactivation process could be predicted by LMH kinetic model.

Application of palladium-modified zeolite for prolonging post-harvest shelf life of banana.

BACKGROUND: The marketability of banana is limited by the rapid rate of ripening. However, the traditional post-harvest technologies may not be desirable. The aim of this study was to investigate the potential of a reusable material for the food preservation industry. RESULTS: The nanocomposite-based palladium (Pd)-modified zeolite (Pd/zeolite) was prepared by impregnating Pd into zeolite. Pd/zeolite had a Brunauer-Emmett-Teller dinitrogen specific surface area of 475 m2 g-1 with crystal structure similar to Y-zeolite. Transmission electron microscopy images showed the dispersion of Pd particles over the multi-pore zeolite support. Pd/zeolite uniquely acted as an adsorbent and a catalyst and was able to remove ethylene even after reaching breakthrough point. To prove Pd/zeolite is reusable, a 99 ± 0.8% ethylene removal efficiency still remained even after five consecutive cycles with repeated use of Pd/zeolite. The presence of Pd/zeolite significantly decreased the ethylene concentration during 18 days of storage at 20 ± 2 °C. CONCLUSIONS: Pd/zeolite could delay the ripening of banana and improve its firmness and the peel color significantly. Findings indicated that the as-prepared Pd/zeolite is an effective adsorbent/catalyst with high potential for practical application in ethylene removal, especially for the post-harvest period. © 2019 Society of Chemical Industry.

Stable carbon isotope fractionation of chlorinated ethenes by a microbial consortium containing multiple dechlorinating genes.

The study aimed to determine the possible contribution of specific growth conditions and community structures to variable carbon enrichment factors (Ɛ-carbon) values for the degradation of chlorinated ethenes (CEs) by a bacterial consortium with multiple dechlorinating genes. Ɛ-carbon values for trichloroethylene, cis-1,2-dichloroethylene, and vinyl chloride were -7.24% ±â€¯0.59%, -14.6% ±â€¯1.71%, and -21.1% ±â€¯1.14%, respectively, during their degradation by a microbial consortium containing multiple dechlorinating genes including tceA and vcrA. The Ɛ-carbon values of all CEs were not greatly affected by changes in growth conditions and community structures, which directly or indirectly affected reductive dechlorination of CEs by this consortium. Stability analysis provided evidence that the presence of multiple dechlorinating genes within a microbial consortium had little effect on carbon isotope fractionation, as long as the genes have definite, non-overlapping functions.

Effective degradation of primary color direct azo dyes using Fe0 aggregates-activated persulfate process.

The present study examined the oxidation power of a Fe0 aggregates/persulfate (PS/Fe0) system for the degradation of the wastewater containing mixed primary direct dyes (i.e., Sirius® Gelb S-2G, Sirius® Red F3B, and Sirius® Turkis GL01). Results indicated that decolorization efficiency was determined by operating parameters of the PS/Fe0 system and the structural complexity of dye molecules. System efficiency increased with increasing persulfate and Fe0 dosages. Faster decolorization was observed in experiments conducted at pH < 10. The process obeyed a first-order kinetics. Slow heterogeneous reactions were observed at high initial pH (>10.5) and low PS concentration (<2 × 10-3 M). Inhibitory effect occurred in systems containing salts Na2SO4, NaCl, Na2CO3, and Na2HPO4 at 1 × 10-2 M. The effect was suppressed when reaction temperature was raised to 55 °C. Heat enhanced not only decolorization efficiency, but also COD removal. Complete decolorization of a mixed dye containing ADMI (the American Dye Manufacture Institute) 15105 was achieved within10 min in the PS/Fe0/55 °C system with an initial pH of 6.0 and dosages of 5 × 10-3 M Na2S2O8 and 0.5 g/L Fe0. Low molecular weight intermediates including organic acids were identified. Due to a relatively low activation energy (4.68 kcaL/mol), the PS/Fe0 system exhibited higher efficiency at higher temperature. This study demonstrated that Fe0-activated PS is a promising process for the treatment of textile wastewaters containing mixed azo direct dyes.

Oxygen exposure effects on the dechlorinating activities of a trichloroethene-dechlorination microbial consortium.

The aim of this work was to study the effects of the presence of oxygen on the dechlorination of trichloroethene by a microbial consortium containing D. mccartyi. The 16S rRNA and reductive dechlorination genes of the functional bacteria and the non-dechlorinators were monitored. Exposing the consortium to oxygen altered the overall biotransformation rate of the dechlorination process, biotransformation processes prolonged with oxygen concentrations changing from 0 to 7.2mg/L, however, trichloroethylene was eventually dechlorinated to ethene. The qPCR analyses revealed that the D. mccartyi strains containing the tceA gene were less sensitive to exposure to oxygen than were the D. mccartyi strains containing the vcrA gene. High-throughput sequencing by Illumina MiSeq indicated that the non-dechlorinating organisms were probably crucial to scavenge the oxygen to protect D. mccartyi from being damaged.

Ultrasound and heat enhanced persulfate oxidation activated with Fe(0) aggregate for the decolorization of C.I. Direct Red 23.

Effluents from the paper printing and textile industries are often heavily contaminated with azo dyes. Azo dyes are difficult to oxidize biologically. This work investigated the decolorization of an azo dye, C.I. Direct Red 23 (DR23), by persulfate (PS) activated with Fe(0) aggregates (PS/Fe(0)). Ultrasound (US) and heat were used as enhancement tools in the PS oxidation system. Neither US-activated PS nor thermally activated PS was effective in oxidizing DR23. However, the decolorization was significantly enhanced by PS/Fe(0) combined with US (PS/Fe(0)/US) or heat (PS/Fe(0)/55 °C). Approximately 95% decolorization of 1×10(-4) M DR23 was achieved within 15 min in the PS/Fe(0)/US system at an initial pH of 6.0, PS of 5×10(-3) M, Fe(0) of 0.5 g/L and US irradiation of 106 W/cm(2) (60 kHz). Complete decolorization was achieved within 10 min in the Fe(0)/PS/55 °C system. The rate of decolorization doubled when US was introduced in the PS/Fe(0) system during the treatment of different initial dye concentrations. The dependence of dye and true color (ADMI) depletion on PS concentration has been discussed. DR23 was completely degraded based on the disappearance of aromatic groups of UV-vis spectra and the variation of TOC mineralization. The observed pseudo-first-order decolorization rate was substantially enhanced by increasing temperature. The Arrhenius activation energy for the PS activated with Fe(0) was estimated as 8.98 kcal/mol, implying that higher temperature is beneficial for the DR23 decolorization. The addition of US into the PS/Fe(0) system did not incur a substantial increase in electricity, whereas the mineralization of DR23 occurred quickly. Thus, both PS/Fe(0)/US and heated PS/Fe(0) systems are practically feasible for the effective degradation of the direct azo dye in textile wastewater.

Characterization of biochars derived from agriculture wastes and their adsorptive removal of atrazine from aqueous solution: A comparative study.

The physicochemical properties of biochars produced from soybeans (SBB), corn stalks (CSB), rice stalks (RSB), poultry manure (PMB), cattle manure (CMB), and pig manure (PgMB) and their adsorption characteristics of atrazine were investigated. The adsorption capacity increased with the increase of temperature and initial atrazine concentration. More atrazine was removed from basic solutions than acidic solutions, due to the effects of adsorption and hydrolysis. The Freundlich isotherm adsorption parameters indicated that the adsorption capacity decreased in the order SBB>RSB>CMB>CSB>PMB>PgMB, which is associated to the pore volume of biochars. The total pore volume and biochar pH were concluded to play important roles in determining the adsorption capacity, and they may have contributed to physical adsorption mechanisms dominating the overall adsorption process (the low activation energy for all of the biochars). Modified Freundlich and intraparticle diffusion models were used to describe the kinetics of the adsorption process.

Decolourization of direct blue 15 by Fenton/ultrasonic process using a zero-valent iron aggregate catalyst.

Decolourization of direct azo dye, direct blue 15 (DB15), by an advanced Fenton process coupled with ultrasonic irradiation (Fenton/US) was investigated. Zero-valent iron (ZVI) aggregates were used as the catalyst. A positive synergistic effect occurred when Fenton's reagent was combined with ultrasonic irradiation. Experimental results showed that the optimum conditions for decolourization were pH 3.0, Fe(0) 1g/L, H(2)O(2) 5.15×10(-3)mol/L with ultrasound density of 120W/L at 60kHz. These conditions yielded 99% decolouration of 4.7×10(-5) M DB15 (4130 ADMI) solution within 10min. DB15 decolouration follows the first-order decolouration kinetics. Although the solutions containing H(2)CO(3), Cl(-), ClO(4)(-), NO(3)(-) and SO(4)(2-) ions did not have a significant effect on the decolouration, the H(2)PO(4)(-) ion did decrease the decolouration rate. High ultrasonic input power accelerated the reaction and increased decolourization efficiency. The cost effectiveness of this process at high ultrasound density could be controlled despite the high electricity costs incurred by the process. ZVI aggregates were reusable; however, an increase in the number of times ZVI was recycled decreased the decolourization rate. This study demonstrates that a Fenton/US process can effectively decolour the direct azo dye DB15 in wastewater.

Magnetic Fe3O4 nanoparticles for adsorptive removal of acid dye (new coccine) from aqueous solutions.

The ability of magnetic Fe3O4 nanoparticles (MFN) to remove new coccine (NC), an acidic dye, from aqueous solutions was studied. Parameters including ionic strength, pH, and temperature were evaluated. MFN, prepared by precipitation method, exhibits an average particle size of 12.5 nm, specific surface area of 85.5 m²/g, and pH(zpc) of 5.9. Results of kinetic adsorption experiments indicated that the pseudo-second-order rate of adsorption increased with increasing initial NC concentration. Findings also revealed that the equilibrium data could be fitted into Langmuir adsorption isotherm. The adsorption is favored at low pH, high temperature, and low ionic strength, whereupon a maximum adsorption capacity of 1.11 x 10⁻4 mol/g was determined for NC. Thermodynamic functions indicated that the adsorption process is spontaneous and exothermic in nature. Tests of regeneration showed that after 5 regeneration cycles the adsorption capacity of NC decreased to 35% to its original capacity.

Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder.

The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 x 10(-4) to 9.28 x 10(-4)mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution.

Adsorption of Cr(VI) from aqueous solutions by spent activated clay.

Adsorption of Cr(VI) onto spent activated clay (SAC), a waste produced from an edible oil refinery company, was investigated for its beneficial use in wastewater treatment. After pressure steam treatment, SAC was used as an adsorbent. The adsorption kinetic data were analyzed and fitted well in a pseudo-first-order equation and the rate of removal was found to speed up with decreasing pH and increasing temperature. Activation energy for the adsorption process was found to be 4.01-5.47 kcal/K mol. The Langmuir adsorption isotherm was used to fit the equilibrium data and the effect of pH, temperature and ionic strength were studied. The maximum adsorption capacities for Cr(VI) ranged from 0.743 to 1.422 mg/g for temperature between 4 and 40 degrees C under a condition of pH 2.0. The studies conducted show the process of Cr(VI) removal to be spontaneous at high temperature and endothermic in nature. From the waste utilization and environment point of view, the work carried out is important and useful. Results obtained can serve as baseline data for designing a treatment process using this low-cost adsorbent for the treatment of wastewater rich in Cr(VI).