Study On The Preparation,modification And Absorption Properties Of Bamboo-based Activated Carbon

With the rapid development of urbanization and industrialization,water pollution in China has become an increasingly serious issue to be addressed.Industrial wastewater,such as dye wastewater and phenol wastewater,generally exhibits the properties of large discharge,complex components and high treatment difficulty,which was unfavorable for the human health and the growth of aquatic organisms,thereby affecting the economic and social sustainable development and ecological civilization construction.Therefore,the treatment of dyes and phenols has become the primary target of wastewater treatment.Activated carbon adsorption was widely accepted to play an increasingly important role in wastewater treatment due to its high adsorption efficiency,low cost and excellent adsorption selectivity.In the present work,bamboo powder,a common biomass resource in China,was used as raw material to prepare bamboo-based activated carbon via phosphoric acid activation method,and the effects of activation conditions such as ratio of agents to material,pyrolysis temperature and pyrolysis time on the yield and removal rate of methylene blue were studied.The results showed that the suitable activation process of bamboo-based activated carbon was listed as follows:the ratio of agents to material was 1.0,pyrolysis temperature was 450?,and the pyrolysis time was 60 min.Under this condition,the yield of bamboo-based activated carbon was 45.86%,and the removal rate of methylene blue reached 98.03% with a concentration of 200 mg/L and 0.05g bamboo-based activated carbon.Subsequently,surface modification of bamboo-based activated carbon using cetyltrimethylammonium bromide (CTAB),sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) as modifiers was performed,and the effects of modification on the removal rates of methylene blue and phenol were systematically studied.The results indicated that the modification imparted bamboo-based activated carbon with improved removal efficiency toward methylene blue and phenol.Specifically,compared to the unmodified one,when the bamboo-based activated carbon modified by CTAB,SDS and SDBS solutions with critical micelle concentration was used to adsorb 100 mg/L methylene blue solution,the removal rates were increased by 7.0%,4.5% and 1.8%,respectively.When CTAB concentration was 0.25 g/L and the concentration of methylene blue solution was 200 mg/L,the removal rate of methylene blue was up to 99.71%.Similarly,when the bamboo-based activated carbon modified by CTAB,SDS and SDBS solutions with critical micelle concentration was used to adsorb 50 mg/L phenol solution,the removal rates were increased by 13.1%,2.2% and 14.3%,respectively.Moreover,at a SDBS concentration of 0.25 g/L,the removal rate of phenol reached 41.48%.Furthermore,Fourier infrared spectroscopy analysis showed that the surfactant was successfully loaded on the surface of bamboo-based activated carbon.SEM images revealed that modified activated carbon exhibited a more uniform surface with denser pore structure.XRD results demonstrated that the bamboo-based activated carbon displayed a limited change in crystal structure after modification,and all samples behaved a disordered stratified lithographic-like crystal structure.Nitrogen adsorption and desorption isotherm as well as pore size distribution analysis presented that the bamboo-based activated carbon contained micropores and mesopores,and the micropores accounted for a large proportion.In addition,compared with unmodified one,the modified bamboo-based activated carbon was found to exhibit a significant improvement in specific surface area and pore volume.Finally,the adsorption performance and adsorption kinetics of modified bamboo-based activated carbon were studied.CTAB modified bamboo-based activated carbon (CAC) was used to adsorb methylene blue.The effects of initial concentration,the added amount of adsorbent,adsorption time,and pH on methylene blue adsorption were studied.Specifically,when the initial concentration of methylene blue was 200 mg/L,the dosage of adsorbent was 0.1 g, and the adsorption time was 60 min,the removal rate of methylene blue for CAC could reach 99.87%,and the pH was found to exert a limited effect on the adsorption of methylene blue.In addition,the adsorption of methylene blue for CAC was confirmed to basically follow the Freunlich isothermal model,and the adsorption behavior of methylene blue can be well described based on the quasi-second-order kinetic equation.Meanwhile,SDBS modified bamboo-based activated carbon (SAC) was employed to adsorb phenol.The influence of related factors on the adsorption of phenol was studied.When the initial concentration of phenol was 150 mg/L,the dosage of adsorbent was 1.0 g,the adsorption time was 40 min,and the pH was neutral,the removal rate of phenol for SAC could achieve 91.64%.The adsorption kinetic behavior of phenol can also be generally described based on the quasi-second-order kinetic equation.In summary,the feasibility of preparation,modification and absorption application of bamboo-based activated carbon was developed and confirmed.Generally,modification process imparted a more uniform structure with denser pore structure to the bamboo-based activated carbon,which could lead to the improved removal rate of methylene blue and phenol.This work might enrich the technology path for the preparation,modification and potential application of bamboo-based activated carbon,facilitate the realization of high value utilization of biomass bamboo resources and play a positive role in the treatment of methylene blue and phenolic wastewater.