Structure And Performance Control Of Biochar/montmorillonite Composites And Technological Design

Recently,using biomass?lignocellulose?to produce bichar/mineral composite is one of the main method to develop and utilize the sustainable sources.However,due to the complex composition of biomass itself,carbonization efficiency is low and energy consumption is large as well.Biomass can be converted to porous biochar composite at low temperature in the presence of montmorillonite?MMT?,which has multi-properties.Besides,biochar can be applied to produce slow-release materials due to strong stability and retention of nutrients.In this paper,biochar/montmorillonite composite?BMC?was prepared by starting from bamboo at different temperature and ratio of raw materials.The prepared products were characterized by X-ray diffraction,Fourier transform-infrared spectroscopy,differential thermogravimetric analysis,scanning electron microscopy,N2 adsorption/desorption isotherms and elemental analysis.The slow-release performance of N,P,K-laden BMC was determined using TFC-203 soil tester.Results were as followed:?1?The d001-spacing of the BMC samples decreased while the heating temperature increased.The evidences of removal of cellulose and lignin,such as the disappearance of the peaks at 1608 and 2932 cm^-1,could be seen in the comparison of the spectrum of BMC-300 and BMC-400.It suggested that montmorillonite facilitated the carbonization of biomass.?2?Different conditions of preparation affected the structure and performance of BMC.BMCs were partially or completely carbonized dependent upon temperatures used for pyrolytic treatments.Under the optimal conditions?dipping method:temperature=400?,Bamboo:MMT=1.5:1,heating rate=5K/min,mixing method:temperature=450 ?,Bamboo:MMT=2:1,heating rate=5K/min?,the BMC with better slow-release performance would be prepared.?3?BET and SEM showed BMC-400 had a BMC-400 has larger surface area.The sample had approximate pore diameter of 15 nm.The result indicated that product possessed mesoporous structure.?4?The results of adsorption experiments indicated as followed:Adsorption of NH₄HCO₃ and KCl fit with the Freundlich equation model,which occurred on the solid-liquid interface.The adsorption was mainly physical adsorption due to intermolecular forces;Adsorption of Ca₃?PO₄?₂ fit with the Langmuir equation model,which was mainly chemical adsorption.The adsorption could be arisen from chemical action or ion exchange interaction.