Treatment of spent wash effluent using Kaolin immobilised nano ZnO photocatalyst and material characterisation

摘要

The distillery effluent causes a crucial ecological impact when disposed untreated into the environment and the removal of the intense brown colour is a much challenging task due to the presence of a polymeric compound - Melanoidin. This research study reports the synthesis and application of a nano ZnO photocatalyst in an immobilised form. The process parameters such as photocatalyst dosage (0.5-2.5 g/L), initial pH (3-11), initial spent wash concentration and treatment time were optimised to attain the maximum spent wash degradation efficiency. The physical and chemical properties of the as-synthesised photocatalyst were characterised by X-ray diffractometer (XRD), high-resolution scanning electron microscopy (HRSEM), energy dispersive analysis X-ray (EDAX), Brunauer-Emmett-Teller (BET) surface area analysis, diffuse reflectance spectroscopy (DRS) and Fourier transform infrared (FTIR) spectroscopy. The percentage colour degradation of spent wash increased from 36.2 to 77.1%, with increasing photocatalyst dosage from 0.5 to 2.5 g/L, respectively. The reaction rate constant (k_(obs)) decreased from 0.0141 to 0.0022 (1/min) with increasing initial spent wash concentration (% dilution) of 5-25%. The photocatalytic degradation experiment performed at optimised process parameters yielded a maximum of 91.2% of spent wash colour degradation.