Adsorption behavior of amine-modified cotton stalk extract on Congo red in aqueous solution

Selective adsorbent materials for the remediation of printing and dyeing wastewater were successfully prepared from cotton stalks by sodium chlorite pretreatment and vinylamine modification. Its dye adsorption test showed that the cotton stalk-based adsorbent had a unique selective adsorption capacity for Congo red, and the maximum adsorption amount could reach 997.1 mg/g. It is worth noting that the environmental factors, such as pH value, salt ion concentration, and surfactant, had a small influence on the process. Exploring the adsorption mechanism, it was found that the process conformed to the quasi-secondary kinetic model (R² > 0.99) and the Langmuir isotherm model (R² > 0.99), in which electrostatic interactions, π-π, and hydrogen bonding played important roles in the adsorption process. Therefore, this environmentally friendly and efficient adsorbent has a broad application prospect in wastewater treatment.