Phosphomolybdic Acid-Catalyzed Oxidative Degradation of Waste Starch: A New Strategy For Handling The Pulping Wastewater

When old corrugated cardboard (OCC) is returned to the paper mill for repulping and reuse, the starch, which is added to the paper surface as a reinforcement agent, is dissolved into the pulping process water. Most of the OCC pulping wastewater is recycled to save precious water resources; however, during the water recycling process, the accumulation of dissolved starch stimulates microbial reproduction, which causes poor water quality and putrid odor. This problem seriously affects the stability of the papermaking process and product quality. In this study, phosphomolybdic acid (H3PMo12O40, abbreviated as PMo12) was utilized to oxidatively degrade the waste starch present in papermaking wastewater to monosaccharides, realizing the resource utilization of waste starch. The results showed that the optimized yield of total reducing sugar (73.54 wt%) and glycolic acid (11.05 wt%)was achieved at 145 °C with 30 wt% PMo12, which is equivalent to 84.59 wt% starch recovered from wastewater. In addition, the regeneration of the reduced PMo12 was realized applying a potential of 1 V for 2 h. Overall, this study has theoretical significance and potential application value for resource utilization of waste starch in OCC pulping process and cleaner management of OCC waste paper.