Decontamination of anthraquinone dyes polluted water using bioinspired silica as a sustainable sorbent

The increased release of harmful dyes in water, along with the continuous reduction of the world’s freshwater supplies has placed the textile industry under greater pressure to safely and effectively treat wastewater effluents. Resistance of reactive dyes to breakdown naturally has highlighted the need for specialised removal methods. The growing need for low-cost, efficient sorbents has led to the exploration of bioinspired silicas (BIS) due to their green synthesis, proven scalability, and versatility for chemical functionalisation required for dye scavenging. Through a systematic approach, the removal of Reactive Blue 19 from water was studied using a range of BIS, and was compared to removal using a commercial sorbent. While 0% removal was denoted for the commercial sorbent, BIS showed up to 94% removal. The results obtained from a kinetic study suggested a pseudo-second-order reaction, indicating a chemisorption process via electrostatic interactions. Examination of the effects of various adsorption conditions (temperature, pH, sorbent and dye concentrations) using isotherm models (Langmuir and Freundlich) indicated that adsorption was of both chemical and physical nature. Examination of the adsorption mechanism suggest that dye adsorption on BIS was spontaneous. BIS showed higher adsorption capacity (334 mg g−1) compared to literature examples, with rapid adsorption under acidic conditions, excellent thermal stability and good reuse potential. These findings highlight the potential of BIS as a sustainable, efficient and low-cost sorbent that could be brought forward for future implementation.