Catalytic wet oxidation: an environmental solution for organic pollutant removal from paper and pulp industrial waste liquor

Abstract

The removal of organics from paper and pulp industrial waste was investigated employing wet oxidation (WO) and catalytic wet oxidation (CWO) techniques using a high-pressure reaction system. Different types of catalysts prepared from single metals (transition/noble) and mixed metals (transition–transition/transition/noble metal) were used in the CWO studies. The paper and pulp liquor treatments were conducted in selected different environments such as (i) liquors with different organic concentrations, (ii) liquors with different pH (11–14), (iii) a range of reaction temperatures (413–463 K), (iv) different catalysts (Cu, Mn, Pd, Cu/Mn, Mn/Pd, Cu/Pd), (v) catalyst loading (1–8 g). The single transition (Cu, Mn) or noble metal (Pd) catalysts showed appreciable total organic removal, but the bi-metal catalysts (Cu/Mn, Cu/Pd, Mn/Pd ) exhibited even higher activity for organics removal. Much higher total organic carbon (TOC) removal (>84%) was achieved by using the CWO process. The TOC removed by the Cu/Pd catalyst was the highest, followed by the Mn/Pd and Cu/Mn catalytic system.