Article

Sustainable transformation of cotton stalk waste as a biochar-based copper-silicon composite for chromium (VI) detoxification

Sana ShakilDepartment of Chemistry, King Abdullah Campus, University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir 13100, PakistanSalah Ud DinDepartment of Chemistry, King Abdullah Campus, University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir 13100, PakistanKhawaja Ansar YasinDepartment of Chemistry, King Abdullah Campus, University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir 13100, PakistanMuhammad Sheraz AhmadCenter for Environmental Sustainability and Human Health, Ming Chi University of Technology, New Taipei City 24301, TaiwanMuhammad ImranUniversity of GdańskAbdurahman Hajinur HiradDepartment of Botany and Microbiology, College of Science, King Saud University, P. O. Box.2455, Riyadh 11451, Saudi ArabiaJamoliddin RazzokovDepartment of Microbiology, Pharmacology, Normal and Pathological Physiology, Kokand University Andijan Branch, Jasorat 43, Andijan 170619, UzbekistanSirajul HaqDepartment of Chemistry, King Abdullah Campus, University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir 13100, Pakistan

Desalination and Water Treatmentjournal2025en

ABI

Abstract

This study investigates the adsorption efficiency of a biochar composite derived from cotton stalks with copper and silicon (CSB-Si-Cu) for chromium (VI) removal from water. Characterization techniques, including XRD, FTIR, EDX, SEM, TEM, XPS, and PZC analysis, confirmed the material's structural and chemical properties. Peaks at 153 eV (Si2p) and 932.1 eV (Cu 2p) validated the presence of silicon and copper, while a peak at 529.9 eV indicated Cr₂O₃/Cr(OH)₃ formation after adsorption. The adsorption followed the pseudo-second-order and Elovich models, with an equilibrium adsorption capacity of 39.63 mol g⁻¹ at 290 minutes. Chromium (VI) removal increased at lower pH and higher temperatures, reaching a maximum of 61.10 × 10⁵ mol g⁻¹ at pH 2 and 41.30 × 10⁵ mol g⁻¹ at 318 K. Adsorption data aligned with Langmuir and Freundlich models, indicating a complex mechanism, while the Temkin isotherm highlighted the role of thermal energy. Thermodynamic analysis confirmed the process as endothermic, spontaneous, and chemisorption-driven. Electrostatic interactions and reduction by oxygen-containing functional groups facilitated chromium removal. CSB-Si-Cu exhibited excellent reusability, maintaining 97.53 %–42.92 % adsorption efficiency over multiple cycles, demonstrating its potential for wastewater treatment and pollutants remediation.

Topics

Adsorption and biosorption for pollutant removal Chromium effects and bioremediation Nanomaterials for catalytic reactions

Identifiers

DOI: 10.1016/j.dwt.2025.101166

Citations and references

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