Treatment of artificial pharmaceutical wastewater containing amoxicillin by a sequential electrocoagulation with calcium salt followed by nanofiltration

Abstract The present study deals with the treatment of an artificial pharmaceutical waste which contained amoxicillin (AMX) by using successively an electrocoagulation (EC) with Ca(NO3)2 as an electrolyte and a nanofiltration (NF) with a Nanomax-50 membrane. The effect of the current intensity and of the operating pressure was investigated for separately EC and NF, respectively. The AMX removal as a function of pH and initial AMX concentration was also investigated for the separately conducted EC and NF processes. The best percentage removal of AMX by EC and NF was recorded to be 52.7% and 99.0%, respectively. In the case of the sequential processes EC followed by NF, the removal of AMX was 98.2% and 97.5% at pH 2.5 and 10, respectively. The contribution of both EC and NF towards the AMX removal efficiency in the case of the sequential process was very much significant. It is remarkable that the EC pre-treated feed into NF was explored with several benefits such as high removal efficiency, calcium involved in EC process, prolonged membrane life and reduced power consumption. The electrogenerated solids (the sediment and the cathode deposit) were characterized using Fourier Transform Infra-red spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Thermo Gravimetry Analysis (TGA). It appeared that calcium was involved in the electrogenerated solids. It gave a cathode deposit of Ca(OH)2 in which some AMX was embedded.