Preparation And Adsorption Behavior Of Sulfate Lignin-based Activated Carbon

Wastewater has caused a large amount of water pollution and has a great impact on human life and health in recent years,especially dyeing waste water.Activated carbon has been widely used as efficient adsorbent for organic dyes and other persistent organic pollutants due to its excellent adsorption activity.However,the high cost,difficult forming and recovery of traditional coal based activated carbon limit its application.To solve this problem,kraft lignin/cellulose acetate composite membrane(KL/CA-M)was prepared through solution mixing and immersion precipitation phase conversion coating technology with high purity kraft lignin,followed by phosphoric acid activation and high temperature carbonization to form lignin based activated carbon with excellent adsorption performance.A series of characterizations were carried out to confirm the structure and activity of the obtaining lignin based activated carbon,including infrared spectroscopy(FT-IR),nuclear magnetic resonance spectroscopy(1H-NMR),thernograviimetric analyzer(TG-DTG),gel permeation chromatography(GPC),field emission scanning electron microscopy(FE-SEM)and surface area analyzer(BET).As the result that the optmum technological conditions for preparing the lignin based activated carbon were 50wt%lignin content for the initial membrane,800 ? for carbonization temperature,60 min for activation time and the ratio of phosphoric acid and initial membrane with the number of L In this case,the specific surface area and pore volume of the resulting lignin based activated carbon were 1375.649 m2/g and 0.714 m3/g,respectively.And the adsorption capacity of methylene blue reached 157.24 mg/g.In this paper,Langmuir,Freundlich,Koblc-Corrigan,Temkin and Rcdlich-Peterson models were applied to fitting the adsorption process for better understanding the adsorption mechanism of lignin based activated carbon and further investigaling its adsorption performance from the micro perspective.The results showed that the adsorption of melthylene blue onto lignin based activatd carbon was an exothermic process and low temperature favored the adsorption efficiency.Monolayer and multilayer adsorption were coexistent during the adsorption process.The pseudo first order model,the pseudo second model,Elovich model and intraparticle diffusion model were used to adsorption process for dynamic analysis,and the results showed that the lignin based activated carbon absorbed methylene blue via both physical adsorption and chemical adsorption,showing a typical pseudo second dynamic behavior and the adsorption process controlled by multiple diffusion.This study not only presented the lignin based activated carbon preparation and application but also provided theoretical support for its application and adsorption mechanism.