Sporopollenin as a sustainable biosorbent for cationic dyes remediation: performance and ecotoxicological evaluation

Crystal violet (CV) and methylene blue (MB) are cationic dyes primarily released from textile industry effluents. These dyes are considered carcinogenic and toxic, potentially harming humans, marine life, and the environment. Sporopollenin (Sp) has been investigated as a promising adsorbent for removing dyes from aqueous solutions. In the dye removal experiments, Sp achieved removal efficiencies of 95.48% for CV and 97.40% for MB. These results were obtained under optimal conditions: 0.2 g of Sp, 5 min of contact time, 20 mg L−1 initial dye concentration, 25 °C, and pH 8 for CV; and 0.1 g of Sp, 5 min of contact time, 20 mg L−1 initial dye concentration, 25 °C, and pH 8 for MB. Adsorption kinetics and isotherm analysis indicated that the pseudo-first-order model and the Langmuir isotherm model best described the adsorption processes for CV and MB dyes, respectively. The adsorption of both CV and MB dyes was thermodynamically spontaneous at room temperature, as evidenced by the negative Gibbs free energy (∆G) values of − 3.88 kJ mol⁻1 and − 0.32 kJ mol⁻1, respectively. Furthermore, Sp demonstrated excellent reusability and good adsorption performance in the treatment of batik wastewater samples. Green chemistry metrics confirmed that the dye remediation technique using this sorbent is both environmentally friendly and safe for humans. The phytotoxicity assessment showed that Sp-treated CV and MB solutions achieved a 100% germination rate in pea seeds, clearly demonstrating that Sp sorbent could effectively mitigate the toxicity of CV and MB dyes. Hence, Sp represents a sustainable alternative to conventional adsorbents for dye removal from water bodies.