Pilot Scale Experiment For Synthcsis Of Superabsorbent Via Irradiation

NK superabsorbent was synthesized via irradiation polymerization by using the2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylamide (AM) as monomers, the trimethyl propane di-allyl ether (TMPDE) as the cross-linking agent and K2CO3as the neutralizer. This superabsorbent has high gel strength, good salt tolerance and biocompatibility. The paper is aimed to realize industrialized production of NK superabsorbent. The pilot scale experiment was carried out on the production line of similar materials on the basis of laboratory tests. We made a comparison of the synthesis process between NK superabsorbent and sanitary SAP optimizing the production line to fit the pilot scale experiment. Through the optimization test, NK superabsorbent formula was adjusted such as monomer concentration, crosslinking agent quality score, neutralization degree and irradiation dose in the experiment. The influences of dynamic irrdiation dose, gel breaking particle size, type of dispersant and drying condition on product performances were investigated by the pilot experiment. Quality examination and toxicology test were carried out and NK superabsorbent was used in field trials. The thesis mainly includes the following contents:1. Adjustment and optimization of sanitary SAP production lineWe made a comparison of the synthesis process between NK superabsorbent and sanitary SAP and introduced the main equipments in production line of sanitary SAP. We adjusted the production line as follow:the problem of drastic reaction heat can be solved and the forced refrigeration is not required outside the reaction kettle attributed to using K2CO3as the neutralizer. We modulated the radiation dose by changing the conveying speed, eliminating the sterilization process and modifying the operating parameters such as prilling machine, vibration fluidized bed, crushing machine.2. Optimization experiment of NK superabsorbent synthetic formulaThe influences of monomer concentration, crosslinking agent quality score, neutralization degree and irradiation dose on product performances were investigated. The monomer concentration (40-42%), dose of crosslinking agent (1.4-1.6‰), neutralization degree (60-70%), irradiation dose in polmerization (600-700Gy) and that in crosslinking (1500-2000Gy) were confirmed as the optimal conditions by experiments.3. Pilot scale experiment of NK superabsorbentThe influences of dynamic irrdiation dose, gel breaking particle size, type of dispersant and drying condition on product performances were studied. And the experiment results indicated that the product has a high productivity and good performance when the dynamic radiation dose was800～2000Gy with the Span-20alcohol solution being used as the dispersant while the particle size of colloid lay in5mm and the drying temperature was130℃.4. Quality examination and field trialsAccording to the related standards, the quality examination and toxicology test were carried out. The results showed that NK superabsorbent is of low toxicity and no irritation with the performances of product being able to meet the requirements of national standards. Field trials were performed in different regions and different types of soil and crops. The results showed that NK superabsorbent has good performances suggesting that using this material not only has good effects in saving water and fertilizer, but also increases production and economic returns.