The Study On The Physical And Chemical Properties Of Biochar Produced Bypyrolysis Of Mmunicipal Organic Waste

Biochar is the solid pyrolysis products of organic waste which owns a highlydeveloped pore structure and stable aromatic structure. After the pyrolysis, the carbonsource of organic waste can be fixed in biochar, and then biocharwill buried into the soil,it would be very slowing in oxidization under natural conditions because of its stablestructure, then the entire processing system can decrease the transformation rate of thehuge carbon resource of MSW to the atmosphere, and the biochar may also improve thehysicochemical properties of soil. Therefore, this paper was mainly concerned withbiochar pyrolysised of urban organic waste components(paper, food residue, wood,fabric and plastic and the combinations of every component)，in order to get theoptimum pyrolysis conditions to the biochar with developed pore structure and a highdegree of aromatic stabilization, the main researches were the influence onphysicochemical properties of biocharby pyrolysis conditions, and analysis of thecorrelation between physicochemical properties and pyrolysis conditions. Throughvarious combinations of the experiment, the following conclusions were obtained afterthe experiments：①With increasing of temperature, the trend of the wood biochar, food redisuebiochar and fabric biochar became richer in the pore structure, with the experimentalresults of increasing specific surface area(at the temperature of800℃, the surface areaof the wood biochar, food redisue biochar and fabric biochar were430.65m2/g、82.38m2/g、361.20m2/grespectively), pore volume(at the temperature of800℃, thepore volume of the wood biochar, food redisue biochar and fabric biochar were0.145cm3/g、0.025cm3/g、0.130cm3/grespectively) and decreasing pore diameter(at thetemperature of800℃, the pore diameter of the wood biochar, food redisue biochar andfabric biochar were2.36nm、3.55nm、2.42nmrespectively); however the specificsurface area and pore volumeof paper biochar, plastic biochar increased firstly and thendecreased with the increase of pyrolysis temperature, the paper biochar was richest inpore structure (the surface was218.07m2/g, the pore volume was0.085cm3/g, andthepore diameter was2.10nm) at the temperature of700℃, while the richest porestructure (the surface was7.68m2/g, the pore volume was0.00064cm3/g, and theporediameter was8.10nm) of plastic biochar appealed at temperature of600℃; Foodresidue biochar and plastic biochar presented poorer in pore structure than the rest of the three components(wood, fabric and paper), especially plastic biochar, which almostdecreased by one order of magnitude. When pyrolysis temperature increased, the porestructure of the group biochar of five components became richer in pore structure.②We found that there were significantly interaction between food residue, plasticand the rest three components, and the impacts on the rest components pore structurewere negative; Fabric, wood and paper were similar in chemical composition, whichresulted that there were little interaction among them at the process of generating cahr.③At700℃, mixed biochar of five components got the minimum ratio of H/C andmaximum ratio of O/C, and (N+O)/C, which meant that the biochar generated at700℃owned strongest aromaticity, hydrophilicity and polarity.④Food residue biochar, fabric biochar, plastic biochar, paper biochar, woodbiochar and and mixed group biochar of components were weakly alkaline. Among fivesingle components, the pH value of food residue biochar was highest, in contrast the pHvalue of the plastic biochar was lowest. The pH value of the five biochar of differentsingle component and the mixed biochar pH rised with increase of the pyrolysistemperature.⑤The results showed that aromatic compounds, hydroxyl, ether and carboxyl weremost common in every kind of biochar of different combinations. There was C-Clabsorption peak in plastic biochar because of the existence of chlorine in PVC whichtook50%in the plastic component. Food residue contained phosphate, so there was aconcentration of phosphate in ash of food residue biochar, which also reflected P-Oadsorption peak in the spectrogram. The aromaticity variation of every singlecomponent biochar showed that the biochar aromaticity of paper, fabric and foodresidue improved with the increase of the pyrolysis temperature, in contrast, the woodbiochar aromaticity lessen with the increase of the pyrolysis temperature and the plasticbiochar aromaticity increased firstly and then decreased. The mixed biochar showed agradual aromaticity enhancement when the temperature rised; The oxygen-containingfunctional groups such as hydroxyl, carboxyl gradually disappeared with thetemperature; When plastic was mixed with the cellulose-containing components, theprocess of HCl would be catalyzed, which would reduce the chlorine content in theplastic biochar.