Study On The Dissolution Characteristics Of OCC Secondary Starch And Its Resource Reuse

In recent years,due to world booming economy and sharp-increased public awareness of protecting environment,much attention is concentrated on the cyclic utilization of Old Corrugated Container（OCC）pulp.However,the obviously dropped mechanical properties of OCC waste paper cannot meet the application requirement in packaging.Therefore,the enzymatic modified starch is widely utilized to make up the strength performance of the OCC.Under this circumstances,simple-preparation and cost-efficient enzymatic modified starch are commonly applied as the strengthening agent,especially in China.However,the enzymatic modified starch（secondary starch）can be dissolved and dissociated out from the surface of recycled fiber during the waste paper recycling process,which will boost the growth of microorganism and increase the COD value of waste water.The dissolution characteristics of secondary starch in papermaking system were investigated by Box-behnken test method.The research objects were simulated secondary starch dissolution rate Y₁,secondary starch dissolution rate Y₂,secondary starch dissolution rate Y₃,secondary starch（AKD）dissolution rate Y₄.The dissolution characteristics and history under kinetic conditions such as temperature,time,solute quality and stirring speed were tested,and the experiment was carried out to verify the dissolution of OCC secondary starch in the actual production process.On this basis,the secondary starch was ion-modified by hydrogen peroxide and detected the difference of physical and chemical properties after modification.The results show that the secondary starch in the single water system,its solubility characteristics are most affected by the quality of the secondary starch,in the actual production,the secondary starch solute quality should be controlled at 5g/L;while the solute quality is fixed,the factors order that affecting the dissolution rate are the temperature（B）>time（A）>stirring speed（C）.In the slurry water system,the high-speed friction is caused by the shearing force of the slurry.The surface secondary starch dissolves faster;Furthermore,while the secondary starch is re-adsorbed to the surface of the fiber after being forming,the secondary starch content flowing into the net is reduced;For the secondary starch formed after the secondary starch and AKD compounded,the secondary starch physicochemical properties change due to the action of AKD,and the secondary starch dissolution rate is further reduced.Based on the secondary starch dissolution characteristics,PAC,CPAM,CMC and attapulgite were used as raw materials in retention system.The experimental results show that the presence of CMC inhibits the wet end performance of papermaking.Adding a certain amount of cationically charged PAC to the front end of CMC/CPAM/attapulgite can improve the negative effect of CMC over-anionization on secondary starch control.Finally,after the ionization modification of the secondary starch,the increase of the degree of ionization can further increase the retention of the secondary starch,and the purpose of resource recycling can be realized.