Preparation Of Polyaspartic Acid Interpenetrating Netword Water Absorbent Resin And Its Adsorption Properties In Heavy Metal Ions

With the development of heavy industry and leather and other industries,heavy metal pollution has become more and more serious.Due to the concealment,persistence and irreversibility of heavy metal pollution,this pollution not only threatens human and animal health through the food chain（water,food and other crops）,but also causes very serious environmental pollution.Therefore,the treatment of heavy metal pollution has attracted people’s attention.PASP shows broad application prospects in the removal of heavy metal ions on account of excellent biodegradability and environmental friendly as well as abundant carboxyl groups and amide groups.In this paper,the intermediate polysuccinimide（PSI）was synthesized with the method of acid-catalyzed thermal polycondensation by L-aspartic acid as raw material,then the PSI was cross-linked by partial ring opening reaction of hexamethylenediamine,finally PASP water absorbing resin was obtained by hydrolyzing of the remaining succinimidyl units in the condition of alkaline,and research the adsorption performance of PASP water-absorbent resin in heavy metal ions.The results showed that the PASP water-absorbent resin exhibited excellent properties in adsorption of Ni²⁺and Pb²⁺,which was 94.64 mg/g and96.99 mg/g respectively,when the concentration of PSI was 0.1 g/m L,the contents of hexamethylenediamine was 6.5 wt%of PSI,the reaction temperature was 35℃,and the reaction time was 3 h.The removal rate was optimal when the amount of adsorbent was 0.5 g/L,the p H of the heavy metal ion solution was 6.5.The removal rate of heavy metal ions by water-absorbing resin has shown a downward trend,and the removal effect of Pb²⁺was greater than that of Ni²⁺with the increase of the initial concentration of heavy metal ion solution.The results demonstrate that the water-absorbing resins conform to the quasi-secondary kinetic model and are mainly chemical adsorption.Furthermore,the PASP/CMS semi-IPN water absorbing resin and PASP/CMS IPN water absorbing resin were synthesized by hexamethylenediamine crosslinked PSI and carboxymethyl starch as raw materials,and research the adsorption performance of PASP/CMS semi-IPN water-absorbent resin and PASP/CMS IPN water-absorbent resin on heavy metal ions.The results showed that the relative adsorption and adsorption rate of PASP water-absorbent resin to heavy metal ions has improved in the presence of CMS.The adsorption amount of Pb²⁺can reach 99.56 mg/g,and the adsorption of Ni²⁺can reach 95.52 mg/g by PASP/CMS semi-IPN water-absorbing resin When the contents of CMS was 50 wt%/KPSI.The relative adsorption amount of PASP/CMS IPN water-absorbing resin to Ni²⁺can reach 99.26 mg/g,Pb²⁺can achieve complete adsorption,and the residual solution after adsorption can reach the national emission standard when the contents of CMS was 20 wt%/KPSI,the contents of cross-linker was 24 wt%/CMS,the cross-linking time was 2h,and the cross-linking temperature was 50℃.The adsorption rate for Pb²⁺by three water absorbing resins was PASP/CMS IPN water absorbing resin>PASP/CMS semi-IPN water absorbing resin>PASP water absorbing resin;the adsorption rate for Ni²⁺was PASP/CMS IPN water absorbing resin>PASP water absorbing resin>PASP/CMS semi-IPN water absorbing resin.The adsorption of heavy metal ions by the two water-absorbing resins showed consistency.The removal rate was optimal when the amount of adsorbent was 0.5 g/L,and the p H of the heavy metal ion solution was 6.5.The removal rate of heavy metal ions by water-absorbing resin has showed a downward trend and the removal effect of Pb²⁺was greater than that of Ni²⁺with the increase of the initial concentration of heavy metal ion solution.The results demonstrate that the two water-absorbing resins conform to the quasi-secondary kinetic model and were mainly chemical adsorption.