Thaum lub sij hawm npaj ntawm biochar, cov txheej txheem kev npaj tseem ceeb tuaj yeem muab faib ua pyrolysis thiab hydrothermal carbonization, nyob ntawm seb cov tshuab pyrolysis siv. Ntau yam tseem ceeb cuam tshuam rau cov txheej txheem kev npaj biochar, suav nrog carbonization kub, carbonization tus nqi, carbonization siab, tshuaj tiv thaiv lub sijhawm nyob, catalysts siv, roj nyob hauv lub sijhawm, thiab hom biomass. Cov xwm txheej no sib sau ua ke txiav txim siab cov khoom thiab cov txiaj ntsig ntawm qhov kawg biochar.
Pyrolysis:
Slow pyrolysis: Ua nyob rau hauv qis kub (300-650 degree) thiab ntev cov tshuaj tiv thaiv lub sij hawm (feem ntau tsawg tshaj li 30 feeb), feem ntau ua gases thiab khoom biochar. Slow pyrolysis yog tus cwj pwm los ntawm cov txiaj ntsig biochar siab, uas tuaj yeem ncav cuag 35%.
Fast pyrolysis: Ua nyob rau ntawm qhov kub thiab txias ceev heev, nrog rau lub sij hawm nyob rau hauv cov khoom luv luv, feem ntau tsim bio- roj thiab ib tug me me ntawm biochar, nrog ib tug biochar yield ntawm kwv yees li 12% los yog tsawg dua.
Microwave pyrolysis: Siv lub zog microwave ncaj qha tshav kub ntawm biomass, uas ua rau muaj cua sov ceev thiab ua haujlwm yooj yim. Txawm hais tias microwave pyrolysis muaj qhov tsis tshua muaj biochar tawm los, nws muaj kev siv zog ntau dua thiab ua rau muaj kev cuam tshuam sai dua.
Hydrothermal Carbonization:
Txoj kev no suav nrog kev ua haujlwm biomass hauv dej subcritical lossis supercritical ntawm 200-300℃hauv lub kaw lus kaw. Nws tsis tas yuav ua kom qhuav ntawm cov ntaub ntawv raw thiab tsim nyog rau kev ua biomass nrog cov ntsiab lus siab noo noo. Hydrothermal carbonization cov khoom muaj cov ntsiab lus carbon siab, thiab cov txheej txheem tswj tau, ua rau nws tsim nyog rau kev npaj cov khoom sib xws.
Gasification:
Biomass yog gasified ntawm qhov kub thiab txias nyob rau hauv ib tug gasifier los tsim combustible gases thiab biochar. Nyob ntawm seb puas siv tus neeg sawv cev gasifying, nws tuaj yeem muab faib ua gasification nrog tus neeg sawv cev gasifying (xws li cua, chav, oxygen, thiab lwm yam) thiab gasification yam tsis muaj tus neeg sawv cev gasifying (dry distillation gasification). Txoj kev no tuaj yeem txo cov ntsiab lus ntawm lwm cov ntsiab lus hauv biochar.
Activation Methods:
Acid activation: Biochar yog kho nrog cov kua qaub (xws li phosphoric acid, sulfuric acid) los txhim kho nws lub cev thiab muaj peev xwm adsorption, thiab txhim kho nws cov tshuaj lom neeg.
Kev ua kom Alkaline: Biomass lossis biochar raug kho hauv cov tshuaj alkaline txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau alkaline. Hlau impregnation activation: Qhia cov hlau los yog hlau ntsev ua ntej los yog tom qab pyrolysis kom endow biochar nrog cov khoom catalytic thiab adsorption.
Gas activation: Kho biochar nrog cov pa roj (xws li chav, CO₂, ozone, thiab lwm yam) ntawm qhov kub thiab txias kom nws qhov chaw saum npoo thiab qhov pore.
