The potential application of photocatalytic processes in the processing of wastewater in the leather industry: A Review

Abstract

Abstract The leather industry is an industry that is not environmentally friendly. This is due to the large amount of solid and liquid waste produced. In every processing of 1 ton of raw skin into leather it takes about 50-150 liters of water and about 300 kg of chemicals. The chemicals commonly used in the production process are chromium, sulfate, sodium sulfate, lime, ammonium sulfate, sodium chloride, sulfuric acid, formaldehyde, pigments, dyes, and antifungal agents. These chemicals make the intensity of the poison produced per unit of output high. In Indonesia, chromium is a tanning agent that is widely used because it is cheap, the tanning process is fast, and it produces stable leather. Disposing of leather tannery wastewater directly without prior treatment can cause serious environmental problems due to the high content of COD, BOD, chromium and dyes. Leather industry wastewater contains around 500-1000 ppm chromium (VI). Several efforts to treat Cr(VI) waste that have been carried out, such as chemical reduction, ion exchange, adsorption with coal or activated carbon and reduction with the help of bacteria have weaknesses, namely the need for very high energy and/or very large amounts of chemicals. This weakness makes the photocatalytic method more prospective and superior for application. This paper was created to briefly review the environmental risks posed by the leather tanning industry, especially Cr(VI) waste, as well as the potential for the application of a photocatalytic process to remove these pollutant parameters.