The superior performance of silica gel supported nano zero-valent iron for simultaneous removal of Cr (VI)

Abstract

Pure nano zero-valent iron (NZVI) was fabricated under optimum conditions based on material production yield and its efficiency toward acid blue dye-25 decolorization. The optimum prepared bare NZVI was immobilized with two different supports of silica and starch to fabricate their composites nanomaterials. The three different prepared zero-valent iron-based nanomaterials were evaluated for removal of hexavalent chromium (Cr(VI)). The silica-modified NZVI recorded the most outstanding removal efficiency for Cr(VI) compared to pristine NZVI and starch-modified NZVI. The removal efficiency of Cr(VI) was improved under acidic conditions and decreased with raising the initial concentration of Cr(VI). The co-existence of cations, anions, and humic acid reduced Cr(VI) removal efficiency. The removal efficiency was ameliorated from 96.8% to 100% after adding 0.75 mM of H2O2. The reusability of silica-modified NZVI for six cycles of Cr(VI) removal was investigated and the removal mechanism was suggested as the physicochemical process. Based on Langmuir isotherm, the maximal Cr(VI) removal capacity attained 149.25 mg/g. Kinetic and equilibrium data were efficiently fitted using the pseudo-second-order and Langmuir models, respectively confirming the proposed mechanism. Diffusion models affirmed that the adsorption rate was governed by intraparticle diffusion. Adsorption thermodynamic study suggested the spontaneity and exothermic nature of the adsorption process. This study sheds light on the technology that has potential for magnetic separation and long-term use for effective removal of emerging water pollutants.

A novel Corchorus olitorius-derived biochar/Bi 12 O 17 Cl 2 photocatalyst for decontamination of antibiotic wastewater containing tetracycline under natural visible light

“…Howbeit, the removal efficiency remained approximately the same with increasing the biochar dose from 150 mg/L to 200 mg/L. The biochar particles might agglomerate with increasing the biochar loading above 150 mg/L which could result in the decline of active area, thereby suppressing the expected higher removal at excessive biochar doses as reported by and Salama et al ( 2022) 37,38 . The same trend was observed for the generated intermediates, where the concentration of the generated by-products increased from 0.9 mg/L to 3.9 mg/L in the case of caprylic acid and from 0.…”

Amine-Rich Porous MOF Nanocrystals for the Selective Capture of Carcinogenic Anions and Organo-Pollutants from the Waste Water Environment at Neutral pH

“…The adsorption isotherms were fitted with both the Freundlich and Langmuir adsorption isotherm models. In the Langmuir adsorption isotherm model, R 2 , respectively. We achieved a S2).…”

“…Bioaccumulation of those toxic pollutants in aquatic species may increase the risk of poisoning in higher tropic levels through the food chain, resulting in various diseases (cancer, immune and neurological diseases, etc.) . In the aqueous phase, chromium remains in both oxidation states: trivalent (Cr­(III)) and hexavalent (Cr­(VI)).…”

“…Bioaccumulation of those toxic pollutants in aquatic species may increase the risk of poisoning in higher tropic levels through the food chain, resulting in various diseases (cancer, immune and neurological diseases, etc.). 2 In the aqueous phase, chromium remains in both oxidation states: trivalent (Cr(III)) and hexavalent (Cr(VI)). However, the higher toxicity of the former (Cr(VI)) is attributed to its greater solubility, mobility, reactivity, and cellular uptake compared to the latter (Cr(III)).…”

Catalytic fabrication of graphene, carbon spheres, and carbon nanotubes from plastic waste

“…The typical peaks near 43.2°and 53.74°disappeared due to existing Ni and Fe. 13,33,34 EDX spectroscopy specied the elemental composition of materials as shown in Fig. 4.…”