Linear and nonlinear isotherm modeling of nitrate removal from aqueous solution by alternating current electrocoagulation

Abstract

Aims: Nitrates in drinking water which may come from nitrogen fertilizers applied to crops are a potential health risk. The present study was conducted to investigate the application of alternating current (AC) in electrocoagulation (EC) process for nitrate removal from aqueous solution and linear and nonlinear isotherm modeling.Materials and Methods: The experiments were performed in pilot scale. The effective parameters including solution pH, the initial concentration of nitrate, total dissolved solids, contact time, and current density were studied. Results: The obtained results showed that with increasing solution pH from 3 to 10, the sinusoidal removal efficiency was observed. With increasing current density from 0.5 to 2 A/cm2, the nitrate removal efficiency was ascended from 32% to 58%. The optimum electrolyte was 2 g/L of NaCl. With increasing contact time and decreasing initial nitrate concentration, the nitrate removal efficiency was enhanced. In addition, the adsorption NO3by AC EC was preferably fitted with Langmuir isotherm. Conclusion: The results showed that the EC process could remove the nitrate to less than Iranian standard limit. The solution pH, current density, and contact time were showed the direct effect and initial concentration of nitrate depicted the reverse effect on nitrate removal efficiency.