Study Of Modified Straw Adsorbent Characterization And Adsorption Performance Of Dealing With Methylene Blue Solution

In this paper, agricultural waste paper straw as raw materials , was modified with chemical modification and composite strains biological modification, for preparation of the dye adsorbent. All kinds of analysis methods were used to study the physical structure and chemical properties , such as specific surface area, the structural configuration, cellulose and hemicellulose and lignin components. Through the laboratory experiment, the adsorption capacity of modified adsorbent of straw to deal with the methylene blue dye solutions was studied under different PH value , adsorbent dosing quantity, initial concentration and the temperature condition, and the model of adsorption thermodynamics and adsorption dynamics were established. The main conclusions are as follows:1.The change of straw's chemical and biological modified physical structure and chemical properties.Using a variety of instruments and the analysis method and modified straw to the physical and chemical structure characterizing the nature, and the results show that, by chemical and biological straw after modification, weightlessness rate have varying degrees of increase, among them, alkalize straw biological modified weightlessness highest rate of 47.3%. Rice stem modified cellulose, half cellulose and lignin and all content change greatly, alkalize straw biological modified half cellulose degradation rate is the highest, from 21.3% to 0.9%. After modification, the colour and lustre of rice stem becomes shallow, fiber obvious thinner, texture is soft. And the biological modification, straw pore increased, microporous structure is improved, specific surface area increases, rice stem by ultrasound biological modification, specific surface area of 3.9 m 2 / g increases to 6.9 m 2 / g. Rice stem after modification, chemical structure changed, cellulose and hemicellulose and lignin, the connection between the hydrogen bonding is interrupted, the content of free groups such as -OH,-COOH,-OCH, increased.2.Chemical and biological adsorption performance of modified straw. Using modified straw to deal with the methylene blue dye solutions, the results show that the alkalify, amination, ultrasonic modification and composite strains of straw adsorbent biological modification processing methylene blue adsorption performance are better than the original solution straw adsorbent. Alkaline modified straw adsorption quantity is the highest, about 52.91 mg/g, far higher than the primitive straw 15.625 mg/g adsorption capacity. After biological modified, the adsorption quantity of alkaline modified straw has further improvement, the biggest adsorption can get 56.083 mg/g.3.The effect of reaction conditions (pH, dosing quantity, initial concentration, temperature) to absorption , when modification straw deals with methylene blue dye. Different reaction conditions on the adsorption effect are studied, and the research shows that, pH value increases as adsorption rate increase. When PH is12, modification of straw methylene blue dye adsorption rate are the highest; when adsorbent dosing quantity is 2 ~ 10 g/L range, absorbent dosing quantity increased, adsorption rate increase. The optimal dosing quantity of primitive straw is 6g/L, and for alkalify, ammoniation and ultrasonic modified straw the best dosing quantity is 4g/L. With methylene blue solution initial concentration increases, adsorption rate increase. With temperature increasing, adsorption increased. Raising temperature can increase the absorption effect.4.Adsorption thermodynamics research. Adsorption thermodynamics research shows that the adsorption isotherm of alkalify, amination, ultrasonic modification and composite strains biological modification straw adsorbent to seal with methylene blue solution are in line with two adsorption isotherm mode which are Langmuir and Freundlich, but the latter's degree of correspondence is better. The straw adsorbent processing of methylene blue adsorption is between single molecule layer and polymolecular layer. The uniformity of adsorption surface of straw adsorbent has certain influence.with adsorption process .The value of enthalpy changeâ–³H of adsorbent processing of modification straw such as alkalify, amination, ultrasonic modification and composite strains biological modification to deal with methylene blue solution are all positive. The adsorbent processing of straw adsorbent to handle methylene blue solution is a process of heat absorption, so raising temperature is good to adsorption.In different adsorption temperature and concentration of adsorption, gibbs free energyâ–³G of adsorbent processing of modification straw adsorption of methylene blue is negative, indicating that adsorbent processing of methylene blue adsorption process of solution is spontaneous.In different adsorption temperature and concentration of adsorption, entropy changeâ–³S of adsorbent processing of modification straw adsorption of methylene blue is negative, indicating that adsorbent processing of methylene blue adsorption process of solution is under a disorder of the state. 5.Research into the dynamics of adsorption.Adsorption dynamics research shows that, adsorbent processing of alkalify, amination, ultrasonic modification and composite strains biological modification straw to deal with methylene blue solution is a fast adsorption process. The sorption processes of alkalify, amination, ultrasonic modified absorbent follow the pseudo-second-order kinetics equation ,and the absorption rate is controlled mainly by liquid membrane diffusionThe sorption processes of composite strains biological modification straw follow the pseudo-second-order kinetics equation and diffusion equation,and the absorption rate is controlled mainly by liquid membrane diffusion and spread within particles.This study provides a new idea with high efficiency and low cost for the dye wastewater treatment; research methods of preparation are broaden ,when use of agricultural waste to make water treatment adsorbent; composite strains biological modification straw are utilized to pervide a new road for the lignocellulose to have a economic, reasonable, high threshold way to use...