Study On Adsorption Properties And Preparation Of Modified Straw-Kaolin Composites

China as a large agricultural country produces 700 million tons of straw every year.It is rich in straw resource,but the straw has not been utilizing fully.Most of the straw are burned directly or discarded in farmland.That can not only waste the resources largely but also pollute the environment.Therefore, new, high efficient and low cost water-treatment chemicals derived from straw can achieve reasonable utilization of resources and the aim of waste control by waste. In this thesis, to prepare modified straw (MS), straw was treated by NaOH alkaline treatment, carboxymethylation modification and quaternization modification.Using intercalation technique of Kaolin modified by MS as the adsorption material, which is environmental friendly and low cost and has a high metal binding capacity to explore the adsorbability of copper ion and methylene blue. Results showed that MS-Kaolin water-treatment materials were of great efficiency in wasewater treatment.More detailes are followed as:(1) MS-Kaolin water-treatment materials derived from MS obtained by NaOH alkaline activation modified Kaolin using intercalation technique.The optimum adsorption conditions of the MS-Kaolin water-treatment materials was the reaction temperature to 25 ℃ for 1 hour with the ratio of 1:4 and the absorbent dosage of 4g/L at the Cu2+ initial concentration of 100mg/L under pH 5.0.Under the optimum adsorption conditions, the removal rate could reach 90%.The results also showed that adsorption curves of copper iron removal fitted Langmuir model and the adsorption rates conformed to the pseudo-second-order kinetics with a good correlation.The maximum adsorption capacity was up to 60mg/g.(2) MS-Kaolin water-treatment materials derived from MS obtained by NaOH alkaline and chloroactic acid activation modified Kaolin using intercalation technique.The optimum adsorption conditions of the MS-Kaolin water-treatment materials was the reaction temperature to 25℃ for 1 hour with the ratio of 2:1 and the absorbent dosage of 5g/L at the Cu2+ initial concentration of 150mg/L under pH 5.0.Under the optimum adsorption conditions, the removal rate could reach 99%.The results also showed that adsorption curves of copper iron removal fitted Langmuir model and the adsorption rates conformed to the pseudo-second-order kinetics with a good correlation.The maximum adsorption capacity was up to 243mg/g.(3) MS-Kaolin water-treatment materials derived from MS obtained by NaOH alkaline and 3-Chloro-2-hydroxypropyltrimethyl ammonium chloride activation modified Kaolin using intercalation technique.The optimum adsorption conditions of the MS-Kaolin water-treatment materials was the reaction temperature to 25℃ for 4 hour with the ratio of 1:2 and the absorbent dosage of 2g/L at the Methylene blue initial concentration of 50mg/L under pH 7.0.Under the optimum adsorption conditions, the removal rate could reach 90%.The results also showed that adsorption curves of Methylene blue removal fitted Langmuir model and the adsorption rates conformed to the pseudo-second-order kinetics with a good correlation.The maximum adsorption capacity was up to 60mg/g.