An integrated chemical approach for the removal of hazardous Cr(VI) and other contaminants of tannery wastewater: Biopolymer-assisted adsorption separation and conversion into valuable materials

• Published in: Separation and purification technology Vol. 330; p. 125220
• Main Authors: Kubra, Khathijathul, Pavithra, V., Gopal, Buvaneswari, Janaswamy, Srinivas
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2024
• Subjects: Adsorption. Biopolymer. Chromium. Chlorapatite. Secondary waste. Valuable products; Adsorption. Biopolymer. Chromium. Chlorapatite. Secondary waste. Valuable products
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2023.125220

[Display omitted] •Shows selective adsorption of Cr(VI) with Qm of 143 mg/g.•Complete removal of Cr(VI) and conversion into Cr2O3, ZnCrO4 demonstrated.•Other ions of filtered water are precipitated as chlorapatite and removed.•Demonstrates the extraction of water from tannery effluent for reuse. To counter the toxic effects of Cr(VI) ions in industrial wastewater, adsorption onto a suitable adsorbent is prudent, but the resulting secondary waste accumulation and cleaning are challenging. Herein, biocompatible alginic acid has demonstrated selective adsorption of Cr(VI) ions with the subsequent conversion of the secondary waste into valuable materials. The maximum sorption was found to be 143 mg/g, and the adsorption follows the Langmuir model and pseudo-second-order kinetics. The process was tested with a simulated tannery effluent where selective Cr(VI) adsorption was achieved, and the secondary waste was converted to Cr2O3 and ZnCrO4. The remaining ions present Na+, Cl+, SO42- have been consolidated into an apatite mineral with the molecular formula of Ca4.1Na0.9(P0.7S0.3O4)3Cl. Overall, our integrated process of removing and converting Cr(VI) ions into beneficial by-products opens up a window of opportunities for large-scale water purification and industrial applications.