Electrocoagulation—photocatalytic process for the treatment of lithographic wastewater. Optimization using response surface methodology (RSM) and kinetic study

• Wastewater mainly from the offset process was collected form a local industry.
• Most of all the color of the wastewater was removed in the electrocoagulation process.
• Pseudo-second order kinetics suggest that intra-particle diffusion process.
• The wastewater was colorless still has a high amount of organic carbon.

In this work, optimization of total organic carbon (TOC) removal for the treatment of lithographic wastewater by electrocoagulation followed by photocatalytic process was developed. It was used a response surface methodology (RSM) for the optimization of the process variables, such as current density for electrocoagulation process, TiO2 concentration for photocatalytic process, and pH in both cases. Optimal conditions for the process were obtained with TOC removal above 65% using electrochemical process by 30 min of operation. A total of 25% of residual TOC was removed employing the photocatalytic process, for a total of 74% of removal of TOC from the initial value. A kinetic modeling was performed for both processes to pseudo-second-order equations. The treated water is colorless and could be suitable for cleaning water in the lithographic process.

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