Pumice modified with didodecyldimethylammonium bromide as a cost-effective, eco-friendly adsorbent for Cr(VI)

Various types of organically modified minerals have already attracted the attention of researchers due to their promising and environmentally friendly properties and their diverse application. This study aims to develop a cost-effective and efficient adsorbent for Cr(VI) removal from wastewater by modifying pumice with acid activation and cationic surfactant treatment. The research focuses on optimising adsorption conditions, understanding the adsorption mechanisms, and evaluating the material’s reusability for large-scale applications. This study improves the properties of pumice (Pmc), surface organomodification using 5 M H₂SO₄ activation and a double-chain cationic surface active agent as an organic modifier, didodecyldimethylammonium bromide (DDAB) for the sorption of Cr(VI). Physicochemical characteristics of natural-pumice and organo-modified one were studied by EDX, SEM, FTIR, TGA, DTA, XRD and N₂ adsorption/desorption tools. The influence of time, Cr(VI) concentrations, solution pH, weight of adsorbent, and temperature were measured and discussed in batch equilibration technique. The results showed rapid adsorption (60 min) with optimal efficiency at pH = 2 for Cr(VI) anions. The removal data fitted the Langmuir model, with a maximum adsorption capacity of 7.81 mg/g. The sorption of these anions onto DDAB/Pmc followed pseudo-second-order rates. Thermodynamic parameters for anions adsorption have been evaluated. The parameters gained from experiments and others can be utilised to design an economical treatment plant for water polluted with Cr(VI) anions or wastewater resulting from industrial.