Development of Biochar-Based Functional Materials: Toward a Sustainable Platform Carbon Material

Preparation, modification and environmental application of biochar: A review

Production and utilization of biochar: A review

A review on novel processes of biodiesel production from waste cooking oil

Biomass thermochemical processes result in a common byproduct char. The char is also called biochar particularly when it is used as a soil amendment for soil health improvement. Effective utilization of biochar is critical for improving economic viability and environmental sustainability of biomass thermochemical technologies. Application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on other biochar applications, such as for catalysis and adsorption. This paper provides an overview of recent advances in several biochar utilizations including its use as catalyst, soil amendment, fuel cell, contaminant adsorbent, gas storage and activated carbon. Discussions on biochar production methods, properties and advanced characterization techniques are also provided. Biochar is a valuable resource, however, its effective utilization require further investigation of its structure and properties, and methods to modify those.

Recent advances in utilization of biochar

A promising catalyst based on a biomass pyrolysis by-product, biochar, has been developed for the production of biodiesel Two carbon-based solid acid catalysts were prepared by sulfonating pyrolysis char with concentrated or fuming sulfuric acids Prepared catalysts were studied for their ability to catalyze transesterification of vegetable oils and esterification of free fatty acids The catalyst sulfonated with the concentrated sulfuric acid demonstrated considerable conversion in free fatty acid esterification, while indicating limited transesterification activity Using the stronger sulfonating reagent, fuming sulfuric acid, resulted in much higher transesterification activity Further investigation of the latter catalyst was conducted to determine the effect of sulfonation time (5 and 15 h) and surface area on the transesterification reaction The surface area of the biochar was increased by chemical treatment using 10 M potassium hydroxide through porosity development The resulting four catalysts were compared for their catalytic activity Results showed the catalyst with the highest surface area and acid density to have the highest catalytic activity for the production of biodiesel from canola oil in the presence of methanol as the reagent Furthermore, the catalyst with the higher surface area indicated higher transesterification activity among the catalyst with similar acid densities The effects of alcohol to oil (A:O) molar ratio, reaction time and catalyst loading on the esterification reaction catalyzed by the sulfonated biochar were also investigated Free fatty acid (FFA) conversion increased with increasing A:O molar ratio, reaction time and catalyst loading The catalyst has a tremendous potential to be used in a process converting a high FFA feedstock to biodiesel

Biochar based solid acid catalyst for biodiesel production

This study reveals a novel method to tailor the micro- and meso-porous structures of activated biochar by exploiting the interaction between pre-carbonization drying conditions and carbonization temperature in KOH activation. Biochar samples were mixed with concentrated KOH and then dried under air or nitrogen for various periods of time (0–280 h) followed by carbonization at 475, 675 or 875 °C. It is confirmed that by manipulating drying conditions and carbonization temperatures, the KOH activated biochar can have a predominantly microporous, mesoporous or a combined (micro/meso) porous structure. The surface area, micropore and mesopore volumes tailored between: 488–2670 m2 g−1, 0.04–0.72 cm3 g−1, and 0.05–1.70 cm3 g−1, respectively. The mechanism of porosity development was investigated by FTIR analysis suggesting conversion of KOH to K2CO3 due to different drying conditions as a major role in tailoring the structure. The application of activated biochar with tailored porosity was investigated for Electric Double Layer adsorption of NaCl/NaOH to be employed in water treatment (capacitive deionization) or energy storage (supercapacitor) processes. The majorly microporous activated biochar (N2-dried activated at 675 °C) showed promising capacitances between 220 and 245 F g−1. Addition of mesoporous structure resulted in capacitances between 182 and 240 F g−1 with significantly reduced electrode resistance and improved capacitive behavior as evidenced by Impedance Spectroscopy and Galvanostatic Charge/Discharge tests.

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A novel method to tailor the porous structure of KOH-activated biochar and its application in capacitive deionization and energy storage.

Heterogeneous catalysts bearing sulfonic acid groups were prepared using biochar as the carbon support. Biochar samples were first treated with KOH before carbonization at different temperatures (450, 675, and 875 °C) then sulfonated using fuming H2SO4 at 150 °C for 15 h. The sulfonated catalysts were characterized using BET surface area and porosity, elemental analysis, total acid density, FT-IR spectroscopy, X-ray diffraction, and thermogravimetric analysis. Catalytic performance was determined via the transesterification of canola oil with methanol. The reaction yield was found to be dependent on both catalyst surface area and total acid density, suggesting that the maximum yield would be obtained for a catalyst prepared from char carbonized between 675 and 875 °C. FT-IR spectra and XRD patterns reveal that higher carbonization temperatures cause an increasing reorientation of the biochar’s carbon sheets toward a more graphite-like structure, decreasing the total acid density despite the increasing sur...

Development of Biochar-based Catalyst for Transesterification of Canola Oil

Biochar-based catalyst for simultaneous reactions of esterification and transesterification

Biochar, a by-product of woody biomass pyrolysis, is investigated as a renewable and low-cost carbon-based electrode material for electric double layer (EDL) applications. To increase the surface area and porosity of the biochar chemical (7 M KOH) and thermal (at 675 and 1,000 °C, respectively) activation treatments are applied. The thermo-chemically activated biochar samples are investigated by a combination of physico-chemical surface characterization and electrochemical methods to reveal the relationship between the activation process variables, the resulting porous carbon structural features and EDL capacitance. For electrochemical testing, the activated biochar is sprayed onto Ni mesh current collectors with or without Nafion® as binder. Based on cyclic voltammetry experiments in 0.1 M NaCl–0.1 M NaOH a maximum EDL capacitance of 167 F g−1 is obtained for the activated biochar electrode prepared at 675 °C. The latter capacitance is about 50 times higher than the EDL capacitance of a Vulcan XC-72 electrode prepared and tested under identical conditions. The activated biochar electrodes show also promising galvanostatic charge/discharge behavior and electrical conductivities up to 0.058 S cm−1 indicating suitability for EDL-type applications.

Amir Mehdi Dehkhoda

Papers

Biochar based solid acid catalyst for biodiesel production

A novel method to tailor the porous structure of KOH-activated biochar and its application in capacitive deionization and energy storage.

Development of Biochar-based Catalyst for Transesterification of Canola Oil

Biochar-based catalyst for simultaneous reactions of esterification and transesterification

Electrosorption on activated biochar: effect of thermo-chemical activation treatment on the electric double layer capacitance