Development of Novel Products from Agro-Wastes(Rice Husks)and Characterization in Kenya

摘要

cqvip:Rice growing is a popular agricultural activity in some areas in Kenya.The challenge is in the disposal of RH(Rice Husks).Rice production results in 20%RH as byproduct.Simple incineration of RH results in RH ash which is a source of valuable chemical products.The ash is 87-97%silica,highly porous and light weight,with a very high external surface area.The end product of RHA(Rice Husk Ash)after chemical treatment,sodium silicate,is a precious commodity that has myriad applications especially in detergent manufacture and soap production.The objective was to determine the best conditions to synthesize silica from agro-wastes(RH)in Kenya.The yield(%SiO2)of the HCl(Hydrochloric Acid)leached RH at 500°C was the highest at 99.2%.Overall these conditions were the best in producing silicate.Percentage(%)removal of each metal is different due to its chemical form in RH.The removal percentage of K is especially remarkable.And 0.5 M HCl leaching followed by thermal treatment of 600°C gave the best increase in%silica dioxide.The same process removed the most metallic impurities(P2O5,K2O,CaO,Mn and Zn).Leaching with 0.5 M HCl followed with thermal treatment of 500°C gave the best overall yield in%silica dioxide.An increase in temperature from 600°C slightly reduced the%silica dioxide content.The 0.5 M HCl used in these trials was able to produce 99.17%silica content from the Mwea RH.The SiO2 obtained with the water washed RH sample is 97.37%as compared 99.17%(HCl-washed)and 99.02%(H2SO4(Sulphuric Acid)-leached).The FTIR(Fourier Transform Infrared Spectroscopy)spectra indicates HCl leaching avails more silica content than H2SO4 leaching.