Biodegradable tamarind kernel powder/kappa‐carrageenan hydrogel for efficient removal of cationic dyes from effluents

Abstract

AbstractAs an adsorbent for wastewater treatment, an eco‐friendly biodegradable hydrogel was utilized in an effort to reduce the hydrogel production costs and decrease its negative impact on the environment. The biodegradable hydrogel of natural polysaccharides, tamarind kernel powder (tkp) with kappa‐carrageenan (kcg), was employed as an adsorbent to remove cationic dyes from an aqueous environment. The impact of factors such as initial adsorbate concentration, pH, contact time, temperature, and adsorbent dosage on maximum adsorption were investigated. The tkp–kcg hydrogel has a remarkable swelling percentage of 1840%. The high water penetration of the tkp–kcg hydrogel made the internal adsorption sites for safranin (SF) and auramine‐O (AO) dye adsorption accessible. The correlation coefficient supported the Langmuir isotherm model's applicability, with maximum adsorption efficiency of 9.372 mg g−1 for SF and 9.225 mg g−1 for AO. The kinetics of adsorption revealed a pseudo‐second order process. Adsorption was an exothermic and spontaneous, according to thermodynamic analyses. Furthermore, the adsorbent was effectively used for five consecutive cycles of SF and AO dye adsorption–desorption. The biodegradation of tkp–kcg hydrogel was characterized by percentage of weight loss, Fourier transform infrared and scanning electron microscopy techniques. The composting technique of biodegradation was used in the biodegradation studies. Using the composting process, 92.6% of the synthesized hydrogel was degraded after 70 days. The results demonstrated that the hydrogel has a high microbiological biodegradability. It is believed that the tkp–kcg hydrogel could have excellent wastewater and agricultural applications due to its high water absorption, excellent retention capacities, cost‐effective and ecofriendly synthesis.Practitioner Points Microwave assisted tkp‐kcg hydrogel was synthesized with the swelling percentage of 1840%. Synthesized hydrogel showed excellent cationic dyes (SF and AO) adsorption capacity with a good recyclability. The synthesized hydrogel showed very good biodegradability of 92.6 % in 70 days by using composite method.