Sustainable wastewater treatment using green adsorbents: Advancing materials for a cleaner future

The increasing burden of water pollution and the growing demand for cost-effective, eco-friendly treatment solutions have directed significant attention toward green adsorbents in wastewater management. These sustainable materials derived from natural, agricultural, and industrial by-products offer an environmentally benign alternative to conventional adsorbents for removing contaminants such as heavy metals, dyes, and other emerging pollutants.

Being the world’s growing economy, Indian textile industry is one of the largest and oldest generators of wastewater containing dyes, heavy metals, and a variety of toxic organic compounds. Conventional treatment methods often fall short in efficiency, cost-effectiveness, or environmental sustainability. As world’s second largest producer of wheat, wheat husk is a readily available agricultural by-product in India. It is an abundant agricultural by-product from wheat processing, was traditionally considered agricultural waste and often used for low-value applications such as animal feed, composting, or as a fuel source. However, with the rise of environmental concerns and the need for sustainable wastewater treatment technologies, researchers began exploring agricultural residues, including wheat husk, as potential low-cost adsorbents.

The washed wheat husk is taken in a covered stainless steel vessels and carbonized at 350°C for 25 min in a muffle furnace further it followed by chemical activation with ZnCl₂ for 20 h at a ZnCl₂/char ratio 1.70 and dried at 100°C. Further process is completed as the dried and Zn impregnated char was carbonized at 600 °C for 20 min. Precaution is taken for activated carbon by treating with 1:1 HCl for the removal of impregnating salt followed by washing with hot distilled water for the removal of chlorides and acidity.

The processed wheat husk was characterized using techniques such as XRD, FTIR and SEM to assess its surface properties and functional groups responsible for adsorption. Batch adsorption experiments were conducted to evaluate its efficiency in removing dyes from textile industry wastewater by varying conditions of pH, adsorbent dose, contact time, particle side and temperature. 86.17% COD reduction and 96.1 % color reduction were achieved at pH 4, temperature 25^oC and adsorbent dose of 2.5 g/dm³. The percentage COD is increased with decrease in adsorbent particle size and decreased with decrease in adsorbent dose. The adsorption data were analyzed using Langmuir and Freundlich isotherm models, and the kinetics were found to follow a pseudo-second-order model with R² ≈ 0.99.  COD adsorption on prepared carbon sample was found to be endothermic as q_m and K_L values were higher at higher temperatures. The value of ΔG°(~-34 kJ/mol) was observed negative which shows the feasibility of prepared carbon for the adsorption process.

 Results indicated that wheat husk has a significant adsorption capacity and can effectively reduce color and COD in textile industry effluents. Its biodegradability, low cost, and regeneration potential make it a promising alternative for sustainable wastewater treatment.

Completed PhD in wastewater treatment of textile dyeing effluent by electrocoagulation and adsorption. Currently, working as Associate Professor in IPS Academy, Institute of Engineering & Sci, Department of Chemical Engineering, Indore, M. P. India. I have more than 13 years of teaching experience along with 1 year industrial experience. I was awarded as a best teacher in year 2017-18 by RGPV Bhopal (M.P). I am editorial board member of American Journal of Chemical Engineering (ISSN No. 2330-8605). I have published number of research papers in national and international peer reviewed journals.