Studies On The Oxidation, Reduction And Oxidation Wastewater Treatment During The DSD Acid Production

In this study, the wastewater from the oxidation of p-nitrotoluene-o-sulfonic acid (NTS) to 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNS) was analyzed, and some 4-nitro-4′-aminostilbene-2,2′-disulfonic acid (ANSD) and 4,4′-diaminostilbene-2,2′- disulfonic acid (DSD) were found. Based on the finding, a new mechanism theory based on DNS anaerobic decomposition was proposed to complete the side reaction mechanism system. This system can help us to optimize the oxidation conditions and increase the yield by increasing the air flow rate.A novel method was also developed to recover more DNS from the oxidation wastewater. However, this new method will also waste most of the aromatic sulfonic acids (ASAs) in the oxidation wastewater. Therefore, we developed a new strategy for treating the oxidation wastewater, which combines an oxidation process, a reduction process, and subsequent alkaline fusion, can transform more than 85% of the ASAs in wastewater into paramycin.Gold nanoparticles supported on four different metal oxides were prepared and applied in the chemoselective reduction of 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNS); H2, CO and HCOONa were selected as hydrogen sources; Compared to conventional catalysts (Pd/C and Raney Ni), excellent selectivity was obtained by the four Au NPs containing catalysts without the generation of 4,4′- diaminobibenzyl-2,2′-disulfonic acid (DAD). Therefore, the prepared gold containing catalysts have potential application in the DSD production.The static analytical method was used to investigate the effects of pH, temperature, and ionic strength on the solubilities of DNS, ANSD and DSD. Based on the results, new processes were proposed to recover more DNS and DSD during their production. In addition, a new purification method was developed to obtain ANSD with purity of >99%.