Study Of Experiments And Mechanism On The Adsorption Of TNT Red Water By Bamboo Charcoal And Rice Husk Biochar

TNT red water is produced by washing TNT with the sodium sulfite during TNT purification.The water has higher COD,color and the concentration of organic materials and is toxic,carcinogenic,mutagenic,and not easily biodegraded.Many methods are used to treat TNT red water and the adsorption is widely used in the project.However,the method of adsorption is limited due to the high costs of the adsorbent.In this dissertation,the Bamboo charcoal(BC)which was produced from the wastes and the remainder materials of the bamboo manufacturing and the Rice husk biochar(RHB)from the bio-oil manufacturing were chosen to adsorbents to treat TNT red water.The adsorption isotherm model,kinetics,thermodynamics,the mechanisms of adsorption,reproducibility and the economic costs were studiedThe modified of BC and RHB were studied firstly.The results showed that ZnCl2 modified BC(ZnCl2-BC)and HCl-HF modified RHB(HCl-HF-RHB)had better adsorption property.The SEM,XRD,N2 adsorption,FTIR,Boehm's titration methods were employed to characterize the structure and adsorption properties of BC,ZnCl2-BC and HCl-HF-RHB.The results showed that the three adsorbents possessed porous structure and the lower graphitization degree.BET surface area was 303.94 m2/g,549.78 m2/g and 185.93 m2/g,respectively.Carboxylic groups,Phenolic groups,Lactonic groups existed on the adsorbents surface.The influence factors such as adsorbent dosage,time,pH value,temperatures and dilution ratio of TNT red water on the adsorption were studied.In addition,the adsorption isotherm model,the adsorption kinetics,thermodynamics,intraparticle diffusion models,external diffusion models,activation energy and adsorption mechanics were studied.The studies showed that the adsorption proceed quickly at the initial stage and became slowly when the adsorbents exceeded certain dosage;adsorption equilibrium time of BC and ZnCl2-BC were 3 h,adsorption equilibrium time of HCl-HF-RHB was 4 h;adsorption effect was best at pH=2.0 for all adsorption systems;the increasing temperature is benefit to adsorb;the larger dilution ratio of TNT red water is,the larger removal degree of COD,the smaller equilibrium adsorption amount.The adsorption of organic materials from TNT red water on BC and ZnCl2-BC followed Langmuir isotherm model and the adsorption of organic materials from TNT red water on HCl-HF-RHB followed Freundlich isotherm model;the adsorption kinetics can be better described by pseudo-second-order model.The intraparticle diffusion process was the rate controlling step for all adsorption processes.The velocity of organic materials transported from liquid phase to the surface of BC,ZnCl2-BC and HCl-HF-RHB was faster than Rice straw actived carbon.The adsorption was spontaneous,endothermic and the randomness increases physical process.The main interaction forces of adsorption were Van der waals force,hydrogen bonding force,electrostatic interactions force and donor-acceptor interaction.The BC and ZnCl2-BC had better reuse performance.The COD of TNT red water treated by BC and ZnCl2-BC were 89 mg/L and 50 mg/L,respectively,and reached the national standard.The cost of the three adsorbents was all low cost which had certain economic and practical value.