Study On Preparation Of Calcium Alginate-based Soft Capsules And Adsorption Of Cu(?)

Calcium alginate@sodium polystyrene sulfonate?PSSA@Alg?soft capsules and calcium alginate@polyacrylamide?PAM@Alg?soft capsules were prepared by titration-curing encapsulation method with sodium alginate as inner coating of sodium polystyrene sulfonate?PSSA?and anionic polyacrylamide?PAM?respectively.The pH of the solution,the dosage of adsorbent,the initial concentration of the solution,the contaction time,temperature,co-existing ions and competitive adsorption on the adsorption of copper???ions by the two materials were studied.The main research contents and results are summarized as follows:The optimum preparation conditions of PSSA@Alg soft capsules were determined by single factor experiments with CaCl₂,PSSA,PAM and rotational speed as the experimental objects,and the adsorption capacity q as the response value.The optimum preparation conditions of soft capsules were determined as follows:the ratio of CaCl₂(w·v^-1)is 2.0%,the ratio of PSSA or PAM(w·v^-1)is 12.5%,and rotational speed is 250 r·min^-1.Different characterization methods including Electron microscope,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to prove the appearance,functional groups and chemical structure of the soft capsules were studied.The PSSA@Alg and PAM@Alg soft capsule was used to adsorb copper???wastewater.The effects of solution pH,reaction time,adsorbent dosage,initial concentration,reaction temperature,co-existing ions,competitive adsorption and other experimental factors on the adsorption capacity were investigated.The results showed that the solution pH=5,reaction time was 24 h,experimental temperature was 303.15 K,adsorbent dosage was 0.5 g?wet weight?,the adsorption capacity of PSSA@Alg or PAM@Alg soft capsule for copper???was143.92 or 266.10 mg·g^-1.Adsorption kinetics data could be described by pseudo-second-order kinetic model.The isothermal adsorption data could be better fitted by Langmuir adsorption isothermal model.In addition,the saturated adsorption capacity of PSSA@Alg or PAM@Alg soft capsule for copper???was 145.56 or 333.33 mg.g^-1.When?G^?<0 kJ·mol^-1,20<?H^?<80 kJ·mol^-1,indicating that the adsorption of copper???by soft capsules is a spontaneous endothermic process,and the adsorption process includes physical adsorption and chemical adsorption.When?S^?>0 kJ·mol^-1·K^-1,indicating that soft capsules increase the material chaos at the solid-liquid interface after adsorbing copper???.Co-existing ion experiments showed that the presence of metal cations hindered the adsorption of copper???by soft capsules,and anions had little effect on the adsorption performance.The results of competitive adsorption showed that the order of adsorption of soft capsules was Pb²⁺>Cu²⁺>Cd²⁺>Ni²⁺>Zn²⁺.After desorption-adsorption experiments,the adsorption capacity of the soft capsule could still reach more than 95.0%?83.0%?of the original.Therefore,PSSA@Alg soft capsules and PAM@Alg soft capsules are promising new functional adsorbents.