Preparation Of Cellulose Composite Hydrogel And Its Application In Water Treatment

Cellulose has no pollution to the environment,high biocompatibility and degradability.It is an ideal water treatment material,but its mechanical properties are poor,and easy swelling limits its application.The study of three-dimensional network hydrogels with excellent mechanical properties and adsorption properties can provide important theoretical references for the application of cellulose hydrogels in water treatment.In this paper,acrylic acid（AA）was grafted onto the long chain of cellulose,and then the carboxyl group of the acrylic side chain was used to form a hydrogen bond with the carbonyl group of the Cucurbit（CB[8]）port and the O-Si-O group of the mineral clay.A hydrogel with high mechanical strength and removal rate was studied,and its adsorption performance was studied by using methylene blue as a model.Details as follows:1.Preparation of waste paper-based acrylic hydrogel（WCF/AA hydrogel）using waste paper（WCF）,acrylic acid（AA）,and Cucurbit（CB[8]）;The structure and morphology were studied by infrared spectroscopy（FT-IR）and scanning electron microscopy（SEM）.The effect of p H on swelling and swelling kinetics of WCF/AA hydrogel were investigated;The effects of different compositions,components and p H on mechanical properties were investigated.The effects of p H,initial concentration,dosage and temperature on the adsorption performance of hydrogel on methylene blue were discussed,and the adsorption kinetics was discussed.The results showed that acrylic acid was grafted onto the cellulose chain and formed a three-dimensional network hydrogel with loose macropores;the hydrogel had a moderate swelling ratio in the range of p H 5～7,which was favorable for adsorption;The stress-strain curve indicates that the hydrogel is a soft and weak polymer with weak mechanical strength;The adsorption of the hydrogel is greatly affected by the initial concentration of methylene blue,and the adsorption amount also increases with the increase,and the adsorption equilibrium can be reached at 120 min;The adsorbent is 0.01 g,the initial concentration is 20 mg·L^-1,the temperature is 35°C,the maximum adsorption capacity is 3.94 mg·g^-1 when the p H is 7,and the removal rate is 97.6%;the adsorption of methylene blue by the hydrogel,which conforms with the pseudo-second-order kinetic model and indicates that the electrostatic interaction of the anion on the surface of the hydrogel plays a common role with the functional groups in the pores,and the pore action dominates.This study provides a reference for the recycling of cellulosic waste and the preparation of environmentally friendly water treatment materials.2.Preparation of two double crosslinker hydrogels using sodium carboxymethyl cellulose（CMC）,acrylic acid（AA）,cucurbit（CB[8]）,attapulgite（ATP）and bentonite（BET）,The two hydrogels are CMC/AA/CB[8]/ATP and CMC/AA/CB[8]/BET hydrogel.The structure and morphology of the two hydrogels were studied by FT-IR and SEM.The effects of p H on swelling and swelling kinetics of CMC/AA/CB[8]/ATP and CMC/AA/CB[8]/BET hydrogel were investigated.The effects of different compositions,component contents and p H on their mechanical properties were investigated.The effects of p H,initial concentration,dosage and temperature on the adsorption of methine blue by two hydrogels were investigated,and the adsorption kinetics was discussed.The results showed that acrylic acid was grafted onto the cellulose chain and formed a smooth and orderly three-dimensional network hydrogel;the swelling process of the two composite hydrogels in water accorded with the pseudo-second-order kinetic model;its moderate swelling rate in the range of p H 4-7 is favorable for adsorption;the stress-strain curve indicates that both hydrogels are soft and tough polymers with high mechanical strength.The mechanical properties of composite hydrogels with different compositions are different.The total elongation at break of CMC/AA/CB[8]/ATP and CMC/AA/CB[8]/BET are 1692%and 1470%,respectively.The corresponding elastic moduli are 0.029 MPa and 0.035 MPa respectively.Under strong acid conditions,the elastic moduli of the two composite hydrogels are increased by 9.1 and 14.2 times,respectively.The mechanical properties of composite hydrogels with different compositions are different.when the CMC,AA,CB[8],and ATP contents were 1.8%,25.3%,72.2%,and 0.24%,respectively,the total elongation at break reached up to 3013%,and the tensile strength was 0.06 MPa,When the contents of CMC,AA,CB[8]and BET are 2.1%,28.7%,68.4%and 0.27%,respectively,the total elongation at break reached up to 3436%,and the tensile strength is 0.10MPa;The adsorptivity of the two hydrogels is greatly affected by the initial concentration of methylene blue,and the adsorption amount also increases with the increase,which can reach the adsorption equilibrium at 60 min;The adsorbent was0.0300 g,the initial concentration was 20 mg?L^-1,the temperature was 35°C,and the maximum adsorption capacity of CMC/AA/CB[8]/ATP hydrogel was 60.3 mg?g^-1 at p H5-7.The adsorbent is 0.05 g,the initial concentration is 20 mg?L^-1,the temperature is35°C,and the maximum adsorption capacity of CMC/AA/CB[8]/BET hydrogel is 67.4mg?g^-1 at p H 6.The adsorption of methylene blue by two hydrogels conforms with the pseudo-second-order kinetic model,indicating that the electrostatic interaction of the anions on the surface of the hydrogel plays a common role with the functional groups in the pores,and the pore action dominates.This research enriches the theoretical research of cellulose hydrogels and provides reference for improving resource reuse.