Electrochemical Advanced Oxidation of Lamotrigine at Ti/DSA (Ta2O5-Ir2O5) and Stainless Steel Anodes

Abstract

The study presents kinetics of degradation and mineralization of an anti-epileptic drug Lamotrigine (LAM) in the aqueous matrix by electrochemical advanced oxidation process (EAOP) on Ti/DSA (Ta2O5-Ir2O5) and Stainless Steel (SS) anodes using sodium sulphate as supporting electrolyte. On both the anodes, kinetic behaviour was pseudo-first-order for degradation as well as mineralization of LAM. On Ti/DSA anode, maximum LAM degradation of 75.42% was observed at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 100 ppm Na2SO4 concentration. Maximum mineralization attained was 44.83% at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 50 ppm concentration of Na2SO4 with energy consumption of 2942.71 kWh/kgTOC. Under identical conditions on SS anode, a maximum of 98.92% LAM degradation was marked after a specific charge (Q) of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 100 ppm concentration of Na2SO4. Maximum LAM mineralization on SS anode was 98.53%, marked at a specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 75 ppm concentration of Na2SO4, with energy consumption of 1312.17 kWh/kgTOC. Higher Mineralization Current Efficiency (MCE) values were attained for EAOP on SS anode for both degradation and mineralization due to occurrence of combined electro-oxidation and electro-coagulation process in comparison to EAOP on Ti/DSA anode due to occurrence of lone electro-oxidation process.

Apparent and true mineralization during combined electro‐oxidation and electro‐coagulation on stainless steel anode

“…Energy dynamics of electrochemical wastewater treatment processes can be quantified as specific energy consumption and expressed as 10,11 where…”

“…One important performance indicator for EO is the mineralization current efficiency (MCE), expressed as 10,11 where…”

“…Accordingly, it was decided to perform each batch experimental run for 5 h. For MET‐HCl, CD is to be studied in the rage 0.67–1.16 mA/cm 2 , while for LAM, the range to be studied is 1.11–1.58 mA/cm 2 . SEC is to be studied in the range of 50–100 ppm for both the target pollutants 10,11 . While studying the effect of CD and SEC, one parameter at a time, it was found that the mineralization first increases and then decreases.…”

“…However, there is a second school of thought that believes in the formation of different oxidant species including hydroxyl radicals at the anode along with the metal ions. These oxidants mineralize the organics present, converting them into simple inorganic species 9–13 . The process, therefore, is a combination of EO and EC.…”

“…These oxidants mineralize the organics present, converting them into simple inorganic species. [9][10][11][12][13] The process, therefore, is a combination of EO and EC. If this be true, a part of the original TOC undergoes true mineralization (TM) into harmless inorganic species through EO, while a part is relocated from the liquid to the electrogenerated solids that separate as sludge because of EC, resulting in AM.…”