Optimization of Cadmium Adsorption onto a Cellulose Acetate–Clay Composite Membrane Using Box–Behnken Design

Cadmium contamination in water poses a serious environmental and health concern due to its high toxicity and persistence. In this context, the development of efficient and low-cost adsorbent materials has attracted increasing attention. This work examines the removal of Cd(II) from aqueous solution using a cellulose acetate–clay composite membrane as an adsorbent material. To evaluate the impact of clay inclusion, membranes were fabricated with varying clay concentrations (0%, 12.5%, and 25%). A Box–Behnken design was used to optimize the process; thermogravimetric analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy were used to analyze the produced composite membranes. The characterization results confirmed the successful incorporation of clay into the cellulose acetate matrix and revealed important changes in the membrane structure and surface morphology. The adsorption performance was strongly affected by operating conditions, particularly temperature, contact time, and clay content. Under the optimal conditions of 30 °C, 4 h, and 5% clay content, the CA-Clay composite membrane achieved a maximum Cd(II) removal efficiency of 93.93% and an adsorption capacity of 12.35 mg/g. These results demonstrate that the composite membrane has a high affinity toward Cd(II) ions, exhibiting its high potential as a low-cost and efficient adsorbent for the removal of Cd(II) from aqueous solution.