Hydrothermal and Pyrolytic Conversion of Biomasses into Catalysts for Advanced Oxidation Treatments

Abstract

Biomasses are very important natural products. Transferring biomass into catalysts for the advanced oxidation process (AOP) via heat treatment has attracted extensive attention. This review systematically introduces and summarizes two kinds of innovative biomass‐based catalysts according to the treating temperature. At low temperature (<300 °C), biomasses are converted into hydrothermal carbonation carbon (HTCC) with semiconductive properties for photocatalysis application. At high temperature (>300 °C), by contrast, the products lose their semiconductive nature and become a conductive carbon‐based conductor (biochar). They usually work as AOP catalysts by activating oxidant of O2, H2O2, and peroxysulfate for environmental treatment. This review summarizes and compares HTCC and biochar according to their formation process, structure, catalytic mechanism, and key points for the activity enhancement. The active units in HTCC are the sp2‐hybridized polyfuran unit while those in biochar are the persistent free radicals, nitrogen‐containing unit, or defects. HTCC converts water into OH radicals by using the photoexcited electron/hole pairs induced by solar illumination, while biochar activates oxidants via the active unit on its surface. More importantly, this review summarizes and demonstrates the key points to obtain high‐efficiency HTCC and biochar catalysts. Finally, conclusions are drawn and the future aspects for biomass‐based catalysis are given.

Co-catalysis of trace dissolved Fe(iii) with biochar in hydrogen peroxide activation for enhanced oxidation of pollutants

“…[1][2][3] Recently, biochar has been found to be an attractive catalyst for advanced oxidation of pollutants. [4][5][6] Specically, biochar can activate H 2 O 2 , 7-10 and persulfates [11][12][13] to produce reactive oxygen species (ROS) such as the hydroxyl radical (cOH), sulfate radical (SO 4 c À ) and singlet oxygen ( 1 O 2 ), which are powerful oxidants (e.g. E q (cOH/H 2 O) ¼ 2.73 V) capable of mineralization of various organic pollutants.…”

Carbon-Based Materials for Oxidative Desulfurization and Denitrogenation of Fuels: A Review

“…Their ability to form oxidizing species (such as hydroxyl radicals) from oxidant sources (such as hydrogen peroxide) has been widely studied [58][59][60][61][62]. They are proven catalysts for oxidation reactions in the liquid phase, either as catalysts on their own or in hybrid forms, such as in water and wastewater remediation [63][64][65][66][67]. Thus, applying those materials in the oxidative removal of sulfur and nitrogen from liquid fuels is a natural extension.…”

The Insolubility Problem of Organic Hole-Transport Materials Solved by Solvothermal Technology: Toward Solution-Processable Perovskite Solar Cells

“…The hydrothermal (solvothermal) method that can impact all chemical events happening with such a high temperature and pressure environment has been well-documented in the field of material preparation, chemical reaction, and processing, resulting in a contrasting outcome with that in ambient temperature and pressure conditions. , In reference to treating insoluble compounds, hydrothermal technology can improve the solubility and trigger the reaction to proceed under critical conditions. For example, for insoluble inorganic reaction precursors, the hydrothermal environment can dissolve them and open the door for recrystallization .…”