Effects of pH on Biochar's heating value during acoustic treatment

Studies have demonstrated the synergism and complexity of ultrasonic (US) treatment biochar (BC) in H2O with dissolved CO2. The objective this study is to elucidate governing mechanistic steps three-phase system by a critical review possible reactions an experimental variables kinetics, which include effects US energy, amplitude CO2 concentration on biochar's properties. Focus placed impacts these pH leading increase BC's higher heating value (HHV) early stage treatment. Such low-energy BC treatments involve two major groups reactions. One starts hydration formation protons, which, turn, extract alkali alkaline earth ions, K+, Na+, Ca+2, Mg+2, etc. From BC. second group US-induced splitting followed H•, •OH, CO, •O•, HCOOH OCH2 fixation C, H O elements These processes lead specific HHV. extent strongly depend feed BC:H2O:CO2 ratio that modulates through hydration. are only source respectively; thus, sufficiently low BC:H2O BC:CO2 ratios facilitate ion exchanges, C fixations, HHV increases. Limited cause oscillatory kinetics multi-component network includes competitive different rates. highest but un-optimized BC's-energy-gain US-energy-supplied observed run was 9.0. This parameter kinetic further suggest adopting pretreatment unit prior gasification.