Determination of torrefaction conditions in boric acid reinforced biochar production by response surface methodology and evaluation of activated biochar forphenol removal

Meeting the increasing food demand with the increasing population, making use of unsuitable lands for agriculture, minimizing the harms of organic pollutants accumulating in the soil through wastewater are the leading research topics that have attracted attention in recent years. Biomass conversion technologies and products play an important role in solving these problems. This study, it was aimed to optimize the production of boric acid supplemented biochar for use in boron-deficient soil and to produce activated biochar with steam to be used in phenol removal from wastewater. Beechwood sawdust, which is a waste of the forest industry, was chosen as the biomass source, and pyrolysis was applied at 500oC. To determine the working conditions in which the product with the highest yield and elemental carbon content is obtained by applying torrefaction at temperatures of 160-240 °C and 30-120 minutes residence times after the biochar is impregnated with different ratios of boric acid (0.25-1.00 gg-1 ), Box-Behnken experimental design, which is one of the statistical experimental design methods, was used. According to the three-factor Box- Behnken design, the highest biochar yield and elemental carbon content were obtained as 91.5% and 83.76%, respectively, at 160 oC torrefaction temperature, 75 min residence time, and 0.25 boric acid/biochar impregnation ratio. In the last stage of the study, water vapor activation was applied to the biochar for 15 minutes at 550oC for the production of activated biochar with an improved pore structure that will act as an adsorbent in phenol pollution that may accumulate in the soil due to wastewater. In continuous adsorption studies; phenol removal was found to be approximately 28% at an initial concentration of 30 ppm, a flow rate of 2 ml/min, and a bed height of 3.5 cm of activated biochar. It has been determined that it would be appropriate to prefer beechwood sawdust, which is a forest industry waste, as a raw material source in the production of environmentally friendly carbonaceous materials. It has been concluded that the biochar produced as a result of thermochemical conversion processes can be used as a soil conditioner or adsorbent directly or after the improvement steps.