Heterogeneous degradation of amoxicillin in the presence of synthesized alginate-Fe beads catalyst by the electro-Fenton process using a graphite cathode recovered from used batteries

Abstract

Iron alginate beads (Fe-Alg) were prepared, characterized and implemented for the degradation of amoxicillin (AMX) by the heterogeneous electro-Fenton process using a graphite cathode recovered from used batteries. Scanning electron microscopy (SEM) showed that (Fe-Alg) beads have a spherical shape and the results of energy dispersive spectrometric (EDS) revealed the presence of iron in (Fe-Alg). Optimization of the operating parameters showed that a complete degradation of AMX was achieved within 90 min of heterogeneous electro-Fenton treatment by operating under these conditions: initial AMX concentration: 0.0136 mM, I = 600 mA, [Na2SO4] = 50 mM, pH = 3, T = 25 °C, ω = 360 rpm. The corresponding chemical oxygen demand (COD) abatement was 50%. Increasing the contact time increased the COD abatement to 85.71%, after 150 min of heterogeneous electro-Fenton treatment. The results of the kinetic study by using nonlinear methods demonstrated that the reaction of AMX degradation obeyed to a pseudo-second-order kinetic. Iron content of 4.63% w/w was determined by the acid digestion method. After 5 cycles of use, the Alg-Fe catalyst depletion was only 8%. Biodegradability was remarkably improved after electro-Fenton pretreatment, since it increased from 0.07 initially to 0.36. The heterogeneous electro-Fenton process had efficiently eliminated AMX and it increased the biodegradability of the treated solution. HIGHLIGHTS The heterogeneous electro-Fenton process was used for the degradation of amoxicillin (AMX).; The Fe-Alg catalyst has proved its efficiency and stability.; The kinetic model of the AMX degradation obeyed to a pseudo-second-order.; The COD abatement and removal yield of AMX were 50% and 100% respectively.; The heterogeneous electro-Fenton pretreatment improved the biodegradability of the AMX from 0.07 initially to 0.36.;

Keywords

• alginate beads
• amoxicillin
• electro-fenton
• graphite
• hydroxyl radicals