Preparation And Application Of Persimmon Tannin-based Superabsorbent Resin

Persimmon tannin-based superabsorbent resin[PT-P（AA-AM）]was prepared from‘Mopanshi’fruit powder（commonly known as"persimmon fruit powder"）as raw material,acrylic acid and acrylamide as monomers,ammonium persulfate as initiator,N,N’-methylene diacrylamide as cross-linker.Single factor experiments were conducted to investigate the influence of different factors on the swelling performance of PT-P（AA-AM）.The optimal formula was as following:the dosage of persimmon powder was 0.3 g·g^-1,the monomer ratio was 4:1,the dosage of initiator was 0.30%,the neutralization degree of acrylic acid was 80%,and the dosage of crosslinking agent was 0.04%.The structure,surface morphology and thermal property of the obtained superabsorbent resins were characterized by Fourier transform infrared spectroscopy（FTIR）,environmental scanning electron microscopy（ESEM）and thermo-gravimetric analysis（TGA）,respectively.The FTIR spectra results indicated that the PT-P（AA-AM）contained a large number of hydroxyl and carboxyl groups,and the new forming ester bond presented that the graft copolymerization had happened.In the ESEM images,PT-P（AA-AM）exhibited rough surface after adding persimmon fruit powder,which increased the contacting area between the resin and water,which could improve the water absorption performance.The results of TGA showed that the quality of the two kinds of resin decreased significantly together with the increase of temperature and presented similar variation pattern,indicating that the addition of persimmon powder had no significant effect on the thermal stability of PT-P（AA-AM）which behave good thermal stability.Studies on the swelling properties of PT-P（AA-AM）showed that:in deionized water and tap water,the swelling capacities of three kinds of resin were similar,while PT-P（AA-AM）presented the highest adsorption rate.Besides,PT-P（AA-AM）had significantly better water retention capacity at room temperature.The reversible swelling and de-swelling of PT-P（AA-AM）could be recovered over many cycles.The degradation rate of persimmon tannin-based superabsorbent resin increased with the adding of persimmon powder.PT-P（AA-AM）’s degradation rate reached 50.34%after 42 days.The results of biosafety experiment showed that PT-P（AA-AM）are bio-safety polymer since it exerted no significant effect on bacterial growth.The results of soil water retention test showed that the addition of superabsorbent resin could improve soil water retention and soil water content in the deeper soil layer.Application of superabsorbent resin can alleviate the water shortage of potted persimmon trees.After 30 days of persimmon seedling transplantation,There was no significant difference in chlorophyll content in the leaves of the three treatments,and the growth of new shoots,the leaf area of new leaves and the survival rate after transplantation were the largest in the treatment group with PT-P（AA-AM）.Field test on‘Eshi 1’includes four treatments:control,drip irrigation,market superabsorbent and PT-P（AA-AM）.There was no significant difference in fruit shape index,fruit moisture content,soluble solids,titratable acid and carotenoid content in those four treatments.The fruit weight,fruit hardness and soluble protein content of drip irrigation were significantly higher than other treatments.At 27.5weeks after flowering,the soluble tannin content of the fruit was lower than 0.2%.In conclusion,PT-P（AA-AM）has excellent swelling capacity and water retention retention capacity.Compared with the market resin,PT-P（AA-AM）’s biodegradability has been improved.Application of PT-P（AA-AM）can alleviate the water loss stress in young trees and potted persimmon trees.