Almond Shell-Derived, Biochar-Supported, Nano-Zero-Valent Iron Composite for Aqueous Hexavalent Chromium Removal: Performance and Mechanisms

Abstract

Nano-zero-valent iron biochar derived from almond shell (nZVI-ASBC) was used for hexavalent chromium (CR) removal. Experiments showed that pH was the main factor (p < 0.01) that affected the experimental results. At a dosage of 10 mg·L−1 and pH of 2–6, in the first 60 min, nZVI-ASBC exhibited a removal efficiency of 99.8%, which was approximately 20% higher than the removal yield at pH 7–11. Fourier transform infrared spectroscopy results indicated N-H was the main functional group that influenced the chemisorption process. The pseudo second-order dynamics and Langmuir isotherm models proved to be the most suitable. Thermodynamic studies showed that the reaction was exothermic and spontaneous at low temperatures (T < 317 K). Various interaction mechanisms, including adsorption and reduction, were adopted for the removal of Cr(VI) using the nZVI-ASBC composite. The findings showed that the BC-modified nZVI prepared with almond shell exerts a good effect and could be used for the removal of Cr(VI).

Photocatalytic Activity of Magnetic Nano-β-FeOOH/Fe3O4/Biochar Composites for the Enhanced Degradation of Methyl Orange Under Visible Light

“…Compared with the average amounts of Fe 3 O 4 and β-FeOOH, the Fe 2+ in the composite ratio is higher than β-FeOOH and lower than Fe 3 O 4 . After β-FeOOH/Fe 3 O 4 is deposited, the C-O binding energy of the sample β-FeOOH/Fe 3 O 4 /biochar remains unchanged, which indicates that β-FeOOH/Fe 3 O 4 is located on the surface of the biochar and is not integrated into the crystal lattice through the formation of chemical bonds [ 31 ].…”

Application of nanoscale zero-valent iron in hexavalent chromium-contaminated soil: A review

“…It is found that the initial pH value has a significant impact on the removal rate of Cr(VI) in soil, no matter what kind of nZVI is wrapped by modified materials [74]. More specifically, the pH value and the Cr(VI) removal rate show a negative correlation [75], that is, with the rising pH value, the Cr(VI) removal rate declines [76].…”

Biotreatment of pyrene and Cr(VI) combined water pollution by mixed bacteria

“…Orthogonal experimental design. Orthogonal testing is often used for optimization of methods 38,39 because it is an efficient process when compared with traditional experimental design. Here, based on the results of single factor analysis (data not shown), the orthogonal experiment, L 9 (3 3 ), involving three factors, namely, the temperature, pH and inoculation amount, was designed to determine the optimal conditions for pollutant removal by the mixed strains (Table 2).…”