Preparation And Performance Study On Biomass Activated Carbon Loaded With TiO₂

In this paper, biomass activated carbon was prepared from pyrolysis bio-char ofpoplar sawdust, a carbon-rich solid product, by chemical activation method andphysical activation method respectively. Activated carbon prepared by chemicalactivation was chosen as TiO₂carrier, and sol-gel method was carried out toprepare photo-catalytic composite material. Following the preparation of thephoto-catalytic, its photo-degradation performance was studied.The activated carbon was prepared by chemical activation with KOH. Theinfluence of mass ratio of alkali to carbon, activation temperature and hold time onthe methylene blue adsorption of activated carbon was investigated. Besides，thestructure and properties of raw materials and activated carbon prepared werecharacterized by experimental means of Nitrogen adsorption experiments, XRD andFTIR detection. The results show that the methylene blue adsorption of activatedcarbon reaches to170mL/g at an alkali to carbon mass ratio of1.5, an activationtemperature of750℃and a hold time of2h. And the activated carbon developedpossesses a large apparent surface area （SBET=1514m²/g） and high adsorptionpore volume （V=0.821cm³/g） with average pore size diameter of2.170nm．Activated carbon was prepared by physical activation with carbon dioxide.The influence of activation temperature, activation time and the flow rate of CO₂onthe methylene blue value of activated carbon were investigated. Based onexperimental optimization methods including the central composite design andresponse surface methodology, optimized parameters were found and the predictedadsorption of methylene blue value was10.66mL per0.1gram, the yield ofactivated carbon was42.66%when the activation temperature was850°C,activation time was3.91h and gas flow rate was30mL per min, while the actualadsorption of methylene blue value was9.8mL per0.1gram, the yield of activatedcarbon was43.58%at this experiment conditions, which was proved to beconsistent with actual. And the model was tested to verify its effectiveness. Besides,the N2adsorption-desorption isotherms experiment of activated carbon preparedwith different activation temperature were conducted, and the BET maximum ofwhich was up to948m²/g while mesopore specific surface area was296m²/g byBJH theoretical and average pore size was3.76nm. Photo-catalytic composites were prepared by sol-gel method using activatedcarbon prepared from chemical as the carrier. Activated carbon and its loadedproduct were characterized by experimental means of XRD, FTIR and SEM detection. Theresults show that prepared TiO₂crystal was coordinate with anatase crystal style.While increasing calcination temperature and loading quantity of TiO₂,the crystalparticles gradually grew up. And the influence of calcination temperature andloading quality on photo-degradation effect of methylorange was investigated. Theresults show that the degradation rate of methylorange solution, which Volume was200mL and concentration was100mg per liter, was up to99.61%, while0.1gramphoto-catalytic composite prepared at the calcination temperature of500℃,owning the loading quality of25.64%was added into the solution.