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.

Present study is a novel attempt to experimentally verify that electrochemical treatment of organic pollutants on stainless steel (SS) anode is a combination of electro‐oxidation (EO) and electro‐coagulation (EC) with quantitative estimation of individual contributions of the two mechanisms. Target organic pollutants, metformin HCl (MET‐HCl) and lamotrigine (LAM), were electrochemically treated with SS anode for this purpose. Experiments were designed using central composite rotatable design (CCRD) to assess the effect of current density (CD) and supporting electrolyte concentration (SEC) as independent process parameters. Under all conditions, the process was experimentally verified to be a combination of EO and EC. For MET‐HCl, true mineralization (TM) as a result of EO contribution varied between 50.13% and 66.64%. EO contribution and resulting TM for LAM ranged from 37.5% to 61.83%. EC contributed 30.6%–31.84% towards MET‐HCl remediation causing the TOC to be transferred from the liquid to the sludge produced (SP). EC contribution was 23.68%–35.89% for LAM remediation. Thus, apparent mineralization (AM), the sum of EO and EC contributions, ranged from 80.63% to 97.79% for MET‐HCl and 61.18% to 96.82% for LAM.Process parameters were statistically optimized using response surface methodology (RSM) to simultaneously maximize TM and AM with minimal energy consumption and maximal current efficiency. The optimized conditions were 0.83 mA/cm2 CD and 86.66 ppm SEC for MET‐HCl. The corresponding values were 1.31 mA/cm2 CD and 79.51 ppm SEC for LAM.

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Present work analyzes the kinetic study of mineralization during electro-oxidation on Ti/DSA (Ta2O5-Ir2O5) and combined electro-oxidation and electro-coagulation on stainless steel anode of an antidiabetic drug metformin hydrochloride (MET-HCl) in synthetic wastewater over a specific charge. Four different reaction orders (0.5, 1, 1.5 and 2) were tested using the integral analysis method by plotting TOC concentration terms over specific charges to determine the exact rate kinetics for the mineralization. The effect of applied current density was evaluated at 50 ppm of sodium sulphate as supporting electrolyte, and the effect of supporting electrolyte concentration was also assessed at a current density of 0.93 mA/cm2 in 50 ppm MET-HCl solution. As a result of (i) electro-oxidation experiments on MET-HCl, carried out on Ti/DSA anode, and (ii) combined electro-oxidation and electro-coagulation experiments carried out on stainless steel anode, based on the R-squared value of the mineralization curves, the first-order reaction rate was proposed.