Chemical And Thermal Stability Comparison Of Biochars Produced From Two Types Of Biomasses

Biochar is a new technique to cope with global warming due to its advantage in carbon sequestration, as long as it keeps stable in soil. This work focused on identifying differences of two biochars-one biochar produced from natural particles with high organic carbon content (peat and sediment) and one biochar produced from straws (maize rods and straw)-on their physic-chemical properties (mostly thermal and chemical stabilities).In this work, the chemical properties and thermal stability of biochar from different sources were investigated by CHNSO lemental analysis, FTIR, XRD and thermogravimetric analysis(TGA-DTA). the oxidation resistance of two varieties of different beaches was assessed based on the loss rate and half-life period of organic carbon. Four oxidants were used for the oxidation experiment of biochars, including NaCIO, H2O2, and KMnO4.We determined that:(1) the oxygen functional groups in the plant or sediment were greatly removed, leading to enhanced hydrophobicity and thermal stability of biochar in the preparing process of biochar. Plant-based biochar has greater carbonize rate. E.g. the C continent of maize rods and straw are51%and76%, respectively, but plant-based biochar has a low production rate. On the contrary, not only sediment biochar has a higher output rate (approximately70%), but delivers a lower carbonize rate then straw biochar due to its massive inorganic component content. Sediment biochar is more stable than straw biochar in heat.(2) We found that chemical stability can be dramatically altered by different preparation temperature, oxidation and origins. E.g. chemical stability:prepared in500℃＞origin>prepared in200℃. The reason so is probably because the physical protection had been damaged and stable carbon structure was yet to be built under low temperature.(3) Same biochar were not always shown exact same stability when merged in different oxidation due to separate oxidant mechanism. E.g. sediment voucher shown better chemical stability in NaOCl and KMnO4then straw biochar, but the opposite phenomenon had been observed in H2O2. We assume this is because protection from inorganic minerals to organic matter has been destroyed by H2O2.(4) During following experiment, we confirmed this assumption by getting rid of inorganic minerals in sediment. Organic component, such as humus, will form complex structure with some minerals.(5)The Straw class biochar’s stability drived from the high plent of lignin and cellulose.But stability varies from different complex type. Further works on stability of complex formed from different component are required.All in all, compare with straw biochar (stability contributed mainly by stable organic matters), stability of sediment biochar is decided by both stable organic matters and protection of inorganic minerals. Thus, with inorganic mineral protection, sediment biochars are more stable in heat and chemical side. Make it an ideal raw material for producing biochar. However, different sediment has a different ingredient due to various nature condition. Future studies on stability of sediment biochar are needed.