Studies in mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) as a hybrid process

Abstract

A hybrid process for mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) is studied. It is important to have maximum conversion of 'N' atoms from the waste to N 2 . The conversion of input 'N' atoms in aniline to N 2 was 15% during wet oxidation without the Fenton process and was improved to 50% with the Fenton process. Therefore, a hybrid process of Fenton followed by wet oxidation was studied for mineralization of the aqueous aniline stream. The parameters for the Fenton process were optimized (pH, catalyst, H 2 O 2 to catalyst (FeSO 4 ) ratio, quantity of H 2 O 2 ). The waste obtained after the Fenton process was then treated by wet oxidation for mineralization by having homogeneous CuSO 4 as the catalyst by keeping FeSO 4 therein. This combined catalyst was found to be more effective for the degradation of the intermediates formed in the Fenton process. Wet oxidation (WO) was studied in the temperature range 473-513 K and the oxygen partial pressure range 0.345-1.38 MPa at pH 6.5. The kinetic data was modeled using a power law rate expression in terms of chemical oxygen demand (COD). The optimum temperature for formation of more N 2 gas was found to be 493 K. The treated waste stream was found to contain oxalic acid using HPLC, and NH 4 + , NO 3 − and NO 2 − ions using ion chromatography analysis.

Enhanced degradation of Bisphenol A from high saline polycarbonate plant wastewater using wet air oxidation

“…It has been proven, by indirect analysis of changing pH during the reaction process, that basic pH in raw wastewater (about 8.5) become slightly acidic in treated wastewater (about 6.5), which can only be due to the formation of short-chain car- boxylic acids. Other studies have also reported similar results in terms of biodegradability index improvement by WAO system for other type of wastewater (Tembhekar et al, 2015;Gunale and Mahajani, 2007;Malik et al, 2014;Weber et al, 2015;Yang et al, 2010). In conclusion, it can be expressed that the WAO process as a pretreatment can provide suitable conditions for biodegradation of treated PCW.…”

“…According to Erjavec et al (2013), in the catalytic WAO process, increasing the reaction time to 90 h and the reaction temperature to 210 • C, the total BPA destruction was obtained (Erjavec et al, 2013). Other review studies have reported that in the CWAO process, the increase of the reaction time had a positive effect on the decomposition of toxic organic matter (Erjavec et al, 2013;Arena et al, 2015;Kim and Ihm, 2011;Al-Momani et al, 2002;Gunale and Mahajani, 2007). So, it can be concluded that the increase of the reaction time improved significantly the mineralization of the PCW effluent.…”

Pilot‐scale treatment of waste‐water from carbon production by a combined physical–chemical process

“…Although chemical precipitation and coagulation are effective in removal of fluoride and SS, they are largely ineffective in removing COD Cr , dissolved organic carbon (DOC) and colour. On the other hand Fenton oxidation has been demonstrated to be quite effective in treating different industrial waste‐waters 14–24. Fenton oxidation tends to destroy the recalcitrant organic chemicals in the waste‐water, resulting in the removal of COD Cr , DOC and colour.…”