Optimization of cadmium adsorption from aqueous solutions by functionalized graphene and the reversible magnetic recovery of the adsorbent using response surface methodology

Abstract

Novel functionalized graphene adsorbent was prepared and characterized using different techniques. The prepared adsorbent was applied for the removal of cadmium ions from aqueous solution. A response surface methodology was used to evaluate the simple and combined effects of the various parameters, including adsorbent dosage, pH, and initial concentration. Under the optimal conditions, the cadmium removal performance of 70% was achieved. A good agreement between experimental and predicted data in this study was observed. The experimental results revealed of cadmium adsorption with high linearity follow Langmuir isotherm model with maximum adsorption capacity of 502 mg g−1, and the adsorption data fitted well into pseudo‐second order model. Thermodynamic studies showed that adsorption process has exothermic and spontaneous nature. The recommended optimum conditions are: cadmium concentration of 970 mg L−1, adsorbent dosage of 1 g L−1, pH of 6.18, and T = 25 °C. The magnetic recovery of the adsorbent was performed using a magnetic surfactant to form a noncovalent magnetic functionalized graphene. After magnetic recovery of the adsorbent both components (adsorbent and magnetic surfactant) were recycled by tuning the surface charges through changing the pH of the solution. Desorption behavior studied using HNO3 solution indicated that the adsorbent had the potential for reusability.

Mechanisms and Adsorption Capacities of Natural and Eco-friendly Nanoparticles for Heavy Metals and Phosphate Ions from Water Using the DSD Approach

“…The analysis based on the data of the system monitoring shows that in some localities the concentrations exceeded the allowed ones (Veljković et al, 2010). Bioaccumulation and biodegradability characterize cadmium and thus classify it as a metal of great toxicological importance (Jafaryan et al, 2019). The UK Department of the Environment and the European Economic Community Hazardous Substances Directive classifies cadmium as a priority pollutant, while in the United States it is listed as a carcinogen B1 (Jie et al, 2016).…”