| Because of the interference of human activities, NaPaHai plateau wetland nitrogen and phosphorus loss increase, the wetland degradation.Biochar as a soil additive not only can improve the soil environment, trapping greenhouse gas, increase food production, but also has the very good application prospect in the reduction of pollutant risk.This study collected rape straw, barley straw and cow dung three wealthy local biomass samples from Napahai Plateau Wetland, the thermogravimetric analysis, the pyrolysis kinetics of biomass was analyzed. And in an oxygen free environment, respectively at300℃,500℃,700℃three temperature for preparing biological carbon. SEM scanning electron microscope, X ray diffraction (XRD), analysis, specific surface area and micropore analysis were used to characterize biological carbon products prepared in laboratory elements. Analyses the influence factors of biochar properties of biomass materials, the effects of preparation conditions on the physical and chemical properties; biological carbon under different temperature difference and biological carbon influence of physicochemical properties on their properties.Research results show that:Although the biomass samples of various shapes, element content, combustible matter content, each are not identical, but with the pyrolysis characteristics of internal very similar composition and similar, pyrolysis characteristics are composed of cellulose, semi cellulose and lignin decomposition of three major components of. Biomass pyrolysis started from about200℃, the main pyrolysis peak appears at300℃～350℃, hemicellulose and cellulose contents than the effects of weightlessness peak shape, three kinds of biomass exhibited three different weight loss characteristics. Due to the poor thermal conductivity of biomass, not internal samples timely warming, lag internal pyrolysis, so as the heating rate increased, the peak shifted to high temperature pyrolysis. Three kinds of biomass sample activation energy were reached its peak at around175kJ/mol, energy distribution are concentrated trend, mainly focused on140-2lOkJ/mol, hemicellulose and cellulose pyrolysis pyrolysis reaction corresponding activation two peak energy respectively, which was significantly less than that before a peak after a peak.Different temperatures of biochar physico-chemical properties were not the same, wherein, the size of the order of the basic rate is300℃,500℃,700℃, although lower preparation temperature biological carbon yield is high, but the adsorption curve showed that the biological carbon, low temperature of biological activated carbon adsorption performance was significantly lower than the the preparation of high temperature, the temperature of500℃above is more appropriate for the preparation of biological carbon. C/O, the content of carbon element, ratio surface area and total pore volume with the preparation temperature is300℃<500℃<700℃, temperature has a great positive influence on them. Biological activated carbon preparation temperature below500℃physicochemical properties of the more obvious changes, relatively speaking, between500～700℃biological carbon structure and properties were relatively stable; preparation of biological carbon from different sources of the same system temperature, the specific surface area and total pore volume is biggest rape carbon, highland barley the cow dung carbon carbon, minimum, micro pore carbon containing a greater proportion of barley, and rape and cow dung is mainly medium and large pore, adsorption of biological activated carbon mainly depends on the pore volume and micropore mesopore proportion, so the barley and rapeseed carbon were better than dung carbon carbon. |
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