Preparation of Modified Cotton Fiber for Efficient Removal of Al(III) Ions from Aqueous Solutions: Adsorption Isotherms and Kinetic Studies

In the present study, a new chelating cellulosic cotton fiber modified with ethylene diamine / eriochrome cyanine r (C-EDA-ECR) has been synthesized to separate Al³⁺ from a matrix of coexisting ions in aqueous solutions via the adsorption process. The cotton fiber was oxidized by periodate to give dialdehyde cellulosic cotton fiber before condensation with ethylene diamine (EDA) and then treated with eriochrome cyanine r (ECR). The successful propagation of (C-EDA-ECR) fiber was confirmed firs by elemental analysis. Then all samples were analyzed via (SEM) and (FTIR), N₂ physisorption, and (EDX). Additionally, the adequate conditions needed for achieving the maximum adsorption amount of Al³⁺ onto C-EDA-ECR were examined, for instance, the impact of solution pH, amount of fiber, initial concentration of Al³⁺ in solution, the effect of changing temperature and contact time. The adsorption experiments proved that the amount of Al³⁺ loaded on the surface of C-EDA-ECR reached 48 mg/ g under ideal working conditions. Chemical adsorption was suggested as the rate-limiting step after 2nd-order model kinetic studies. As well, the Langmuir model proved to fit the adsorption isotherm experiments. The ability to apply the proposed method on some real samples containing Al³⁺ was carried out and the results are auspicious.