Preparation Of HEC-Based Hydrogel Composites And Study Of Their Conductivity,Adsorption Properties

Hydroxyethylcellulose（HEC）is a derivative of cellulose after alkalinization and etherification,which can be dissolved in cold and hot water.It is easily modified because of has a rich hydroxyl structure,non-toxic and degradable,and has good water retention and dispersibility.Therefore,it can be used in coatings,resins,biopharmaceuticals and other applications.Hydrogels are polymeric materials with a three-dimensional network,which can be modified by design to give the material a variety of functions and broaden its application areas.This paper is based on HEC hydrogels with the introduction of polymers and inorganic particles.Composite materials with certain functionalities are synthesized and characterized morphologically and structurally.The materials are made to have electrical conductivity,high water absorption and adsorption properties,respectively.In the first part,the conductive polymer polypyrrole was introduced into a hydroxyethyl cellulose hydrogel network.Pyrrole is mixed with HEC by a one-step process,followed by the addition of an oxidant agent and dopant.The conductive polymer polypyrrole was introduced into a hydroxyethylcellulose hydrogel network.Pyrrole is mixed with HEC by a one-step process,followed by the addition of an oxidant agent and dopant.After the polymerization reaction,the addition of polyvinyl alcohol continues.The final conductive polymer network is formed after freeze-thaw cycles.The optimum content of HEC was determined to be 2 wt%based on a combination of electrical conductivity and mechanical properties.This conductivity was 7.07 S·m^-1,with a tensile stress of 0.68 MPa and a strain of280%.Hydrogels were prepared by using ferric chloride and ammonium persulfate as oxidants.The effects of the type and amount of oxidant on the hydrogel properties as electrical conductivity,mechanical properties,water retention and sensitivities are discussed.Final assembly of flexible sensors to detect the movement of different body parts.It showed good sensitivity and durability.In the second part,inorganic particles of kaolinite（Kaolin）and titanium dioxide（Ti O₂）were loaded into a HEC hydrogel network to prepare a synthetic hydrogel with high water absorption capacity.The experiments were conducted with HEC and polyacrylic acid as the substrate.The optimum amounts of HEC,N,N’-Methylenebisacrylamide and ammonium persulphate were first determined to be 1 g,0.25%and 0.45%.The addition of inorganic particles to the hydrogel system was found to be effective in increasing the water absorption capacity of the hydrogel after swelling experiments.When 0.06 g Kaolin was added,the swelling rate was 45272%,2.4 times the water absorption capacity of the hydrogel without the inorganic particles,and when 0.3 g Ti O₂ was added,the swelling rate was 40674%.The hydrogels were tested for their ability to absorb water in different environments（p H,temperature,salt solution）and were found to have good p H sensitivity and salt solution sensitivity.In the last part,inorganic particle loaded synthetic hydrogels were used as adsorbents to investigate their ability to treat the cationic dye methylene blue.Experiments have confirmed the good adsorption capacity of both inorganic particles when loaded with hydrogels.Hydrogels synthesized with Kaolin as an inorganic filler were used as adsorbents.It was determined that the best adsorption capacity of the hydrogels was achieved at 0.06 g of Kaolin.When the adsorption temperature was 45°C,the amount of adsorbent was 0.5 g/L,initial concentration of the dye was 500 mg/L.The hydrogel had the best adsorption capacity（The maximum adsorption capacity was 928.9 mg/L）.The best adsorption capacity of the hydrogel was achieved when loaded with Ti O₂ at 0.1 g.At an ambient temperature of 25°C,an adsorbent dosage of 0.3 g/L and an initial concentration of 500 mg/L of dye.The maximum adsorption capacity of the hydrogel was 1380.0 mg/L at an ambient temperature of 25°C,an adsorbent dosage of 0.3 g/L and an initial concentration of 500 mg/L of dye.The hydrogel prepared with titanium dioxide as the inorganic filler has a better adsorption capacity than the hydrogel with kaolin as the inorganic filler when both hydrogels have the same amount of adsorbent.Both adsorption processes follow the Langmuir function and conform to a quasi-secondary kinetic model.