A porous polyaniline-Fe 2 O 3 nanocomposite (PANI-Fe 2 O 3 ) with a specific BET surface area of 78 m 2 g −1 was synthesized and evaluated for the removal of organic and inorganic contaminants from aqueous media. Methyl orange and hexavalent chromium Cr(VI) were selected as model pollutants to investigate the adsorption performance of the nanocomposite. Batch adsorption studies revealed maximum monolayer adsorption capacities of 367.64 mg g −1 for methyl orange and 444.44 mg g −1 for Cr(VI), with rapid uptake occurring within 100 min. The effects of adsorbent dose, initial contaminant concentration, contact time, solution pH , and temperature were also systematically examined. Thermodynamic analysis yielded negative change in Gibbs free energy (ΔG) confirming the spontaneous nature of the adsorption process. The nanocomposite also demonstrated favorable reusability, retaining substantial removal efficiency over five regeneration cycles. A plausible adsorption mechanism is proposed based on physiochemical attributes of the nanocomposite. Overall, the results demonstrate that the porous PANI-Fe 2 O 3 nanocomposite is a promising and sustainable adsorbent for wastewater treatment, supporting improved water quality and contributing to broader environmental protection efforts. By enabling effective removal of hazardous dyes and heavy-metal species, this study directly advances Sustainable Development Goals 6 (Clean Water and Sanitation), 14 (Life Below Water) and 15 (Life on Land) and promotes the protection of aquatic and terrestrial ecosystems.
Saini et al. (Sat,) studied this question.