Removal of Chromium (VI) by a Magnetic Nanoscale Zerovalent Iron-Assisted Chicken Manure-Derived Biochar: Adsorption Behavior and Synergetic Mechanism

Adsorptive performances and valorization of green synthesized biochar-based activated carbon from banana peel and corn cob composites for the abatement of Cr(VI) from synthetic solutions: Parameters, isotherms, and remediation studies

This study intended to remove Cr(VI) from an aqueous synthetic solution employing synthesized biochar adsorbent from a blend of locally sourced banana peel, and corn cob biomass wastes. An equal ratio of the prepared powder was activated with ZnCl2 solution (1:1 wt basis) and carbonized for 2 h at 600 °C. The proximate analysis of the selected BP-CCAC@ZC3 biochar was conducted. Subsequently, its surface area, surface functions, and morphology were examined using BET analysis, FTIR, and SEM techniques, respectively. The proximate analysis of BP-CCAC@ZC3 showed a moisture content of 2.37 ± 0.80 %, an ash content of 8.07 ± 0.75 %, volatile matter of 19.38 ± 2.66 %, and fixed carbon of 70.18 %. It was found that the synthesized BP-CCAC@ZC3 had 432.149 m2/g of a specific area as per the BET surface area analysis. The highest efficiency for Cr(VI) removal was determined to be 97.92 % through adsorption batch tests using a dose of 0.4 g of BP-CCAC@ZC3, an initial Cr(VI) concentration of 20 mg/L, pH of 2, and 35 min contact time. Likewise, the adsorption process was effectively described by the Langmuir isotherm model, which had a high correlation coefficient (R 2 = 0.9977) and a maximum adsorption capacity of 19.16 mg/g, indicating a monolayer adsorption mechanism. The BP-CCAC@ZC3 biochar exhibited reusability for up to four cycles with only a slight decrease in effectiveness, highlighting its potential for sustainable wastewater treatment. Overall, using corn cob and banana peel composites to synthesize activated carbon with ZnCl2 offers a promising method for effectively removing Cr(VI) containing wastewater.

Removal of cadmium from aqueous solution by magnetic biochar: adsorption characteristics and mechanism

Experiments were conducted to investigate the potential of the efficient resource utilization of waste cow manure and corn straw in an agricultural ecosystem. In this study, a magnetic cow manure and straw biochar were synthesized by a co-precipitation method, and cadmium (Cd(II)) was removed by adsorption in aqueous solution. Several physicochemical characterization techniques were applied, including SEM, BET, Zeta, FTIR, Raman, XPS, and VSM. The effects of pH value, magnetic biochar content, adsorption kinetics, and isothermal adsorption on the adsorption of Cd(II) were investigated. The physicochemical characterizations revealed that the physical and chemical properties of the magnetic biochar were substantially changed compared to the unmodified biochar. The results showed that the surface of the biochar became rough, the number of oxygen (O)-containing functional groups increased, and the specific surface area increased. The results of the adsorption experiments showed that the adsorption capacity was affected by pH, magnetic biochar addition, Cd(II) concentration, and adsorption time. The adsorption kinetics and isothermal adsorption experiments showed that the Cd(II) adsorption processes of the cow manure and corn straw magnetic biochars were consistent with the Freundlich model and pseudo-second-order kinetic model. The results also showed that the Cd(II) adsorption effect of cow manure magnetic biochar was found to be more effective than that of corn straw magnetic biochar. The optimal conditions for Cd(II) adsorption were 800 ℃ for cow manure magnetic biochar, with a pH value of 5 and 0.14 g biochar addition, and 600 ℃ for straw magnetic biochar with a pH value of 8 and 0.12 g biochar addition. In conclusion, the cow manure magnetic biochar was an effective adsorbent for the absorption of Cd(II) in wastewater.

Immobilized nanoscale zero-valent iron for synergistic enhanced removal of pentachlorobenzene with Pseudomonas sp. JS100

Highly chlorinated benzenes usually have a low efficient degradation in environment. Here we proposed a synergistic removal strategy of pentachlorobenzene (PeCB) using Pseudomonas sp. JS100 coupled with immobilized nanoscale zero-valent iron (NZVI). The structural and textural features of the synergistic system were characterized by X-ray powder diffraction, field emission scanning electron microscopy, and a specific surface area and pore size analysis. Nanoscale zero-valent iron particles were dispersed and attached to the biofilter, which increased the specific surface area to 34.5 m2 g−1. The batch experiment revealed that the removal efficiency of PeCB reached 80.2% in the synergistic system within 48 h. The degradation followed pseudo-first-order reaction kinetics, and the reaction rate constant was measured to be 0.0336 h−1. In the degradation mechanism, PeCB was degraded by NZVI to lower chlorobenzenes, which were utilized by Pseudomonas sp. JS100 as nutrients, thereby achieving rapid removal of PeCB.