Response surface methodology for optimization of simultaneous Cr (VI) and as (V) removal from contaminated water by nanofiltration process

This article is carried out to investigate the optimal operating condition for nanofiltration (NF) process for the simultaneous removal of chrome (VI) and arsenic (V) ions from contaminated water in which effects of various operating conditions, for example, Cr concentration (0.05, 0.5, 5), As concentration (0.01, 0.1, 1), pH (5, 7, 9), and recovery rate (40, 60, 80%), are investigated. The design of experiments is carried out using response surface method (Box‐Behnken design). The results show that by increasing pH and decreasing recovery rate, the removal rate of chrome and arsenic ions increase. With an increase in chrome and arsenic concentration, arsenic removal efficiency increases, whereas, the chrome removal efficiency decreases to 65.5%. The pH is the main parameter influencing the removal rate. There is an adequate agreement between real data and that obtained from the models (R 2 was found to be 0.992 and 0.962, for Cr (VI) and As (V) rejection, respectively). The optimum levels of a chrome concentration of 0.545 mg/L, pH of 9, arsenic concentration of 0.172 mg/L and recovery rate of 42% is applied in predicting the Arsenic and chrome removal efficiency of 99.1% and 83.8%, respectively. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 434–443, 2018