Membrane nanofiltration of cadmium-containing wastewater by a modified polysulfone membrane: experimental and statistical analysis
摘要
Today, heavy metals cause severe environmental crises. Cadmium is one of the heavy metals that are important in environmental pollution. In this research, a flat sheet membrane was constructed and used to separate cadmium from synthetic wastewater. Also considered a combined process of cadmium removal by integrating nano-silica into polymer membranes, resulting in a notable increase in separation efficiency and membrane flux. The efficiency of the nanofiltration membrane was evaluated using two factors: separation rate and passing flux. To check and optimize the membrane performance, the test plan of the response procedure used, the polysulfone concentration, nano-silica concentration, pH, and pressure were known as affecting parameters. The quadratic model of the surface response was 98.51% consistent with the separation test and 95.95% with the passing flux test. The adequacy of the model was checked using the table of variance analysis and the results elucidated that the RSM model had good accuracy with experimental results. In the study of the separation rate, the maximum removal rate of cadmium was obtained as 41%, which, while lower than some nanomaterial-enhanced membranes, offers a cost-effective and environmentally friendly approach. Experimentally, which was obtained in the optimal conditions including 21wt% polysulfone, 0.6 wt% nano-silica, pH 6, and P = 6 bar. In inspection of the passing flux, maximum effluent passing through the membrane at the optimum conditions involved 17wt% of polymer, 0.7 wt% of nanoSiO2, 6 acidity, and 8 bar pressure obtained as 220