Lignocellulosic biomass wastes can be considered as renewable and abundantly available resources, but it is a big challenge to convert them into valuable products via environmentally friendly and cost-effective approaches. Herein, a facile twostep hydrothermal-pyrolysis method is developed to fully convert the lignocellulosic biomass wastes into N-doped biochar-stabilized Co nanoparticles (Co−N/biochar) and bio-oil enriched with valueadded small compounds. The as-synthesized Co−N/biochar, with uniform N doping and well-dispersed Co nanoparticles, presents favorable activities for activating peroxymonosulfate (PMS) to degrade refractory organic contaminants. The underlying PMS activation and pollutant degradation mechanism is illuminated with free radical quenching experiments and an electron paramagnetic resonance analysis. The nonradical pathway is demonstrated to be dominant in the pollutant degradation with the PMS/Co−N/ biochar system. The singlet oxygen ( 1 O 2 ) generated from PMS activation is identified as the main contribution species for the pollutant degradation process. This work will provide a new approach to fully convert the biomass wastes into bio-oil and functional biochar materials with prominent activities.
The conversion of lignocellulosic biomass waste into fuels and chemicals can be regarded as a carbon-neutral circular framework, which is particularly appealing for our sustainable society. In this work, we constructed a homogeneous Lewis acid catalytic system using CoCl 2 as a catalyst to efficiently convert the lignocellulosic biomass waste into 5-hydroxymethylfurfural (5-HMF)enriched bio-oil by a hydrothermal process. CoCl 2 could selectively catalyze the decomposition of cellulose and hemicellulose in the lignocellulosic biomass to produce 5-HMF in a maximum yield of 22.8%, leaving the hydrothermally carbonized lignin as the residual hydrochar. The hydrochar with a high Co(II) content was further converted into biochar-stabilized Co nanoparticles via a pyrolysis process, producing considerable amounts of light hydrocarbons, aromatics, phenols, and vanillin and forming no solid waste. The as-synthesized biochar-stabilized Co nanoparticles were then used as catalysts and exhibited a favorable catalytic activity and recyclability. This work would provide a new approach in lignocellulosic biomass conversion to simultaneously produce valuable chemicals and functional biochar materials.
Heterogeneous electro-Fenton is an efficient advanced oxidation process for the degradation of refractory organic contaminants in wastewater, and its efficiency is governed by cathodic catalysts. In this work, the Fe, N doped biochar materials (Fe/N/ biochar) were synthesized via a simple ionothermal carbonization of biomass and used as a cathodic catalyst for heterogeneous electro-Fenton. The as-synthesized biochar materials with uniform doping of N and Fe significantly improved the performance of the electro-Fenton process via promoting the two-electron transfer oxygen reduction reaction for H 2 O 2 production and subsequent H 2 O 2 activation for reactive oxygen species (e.g., • OH and • O 2 − ) generation. The Fe, N doped biochar catalyst showed excellent recyclability in the cycle runs of the electro-Fenton process, in which its catalytic activity did not fade but continuously increased. Based on the ex situ high resolution transmission electron microscopy and electron paramagnetic resonance results, more active catalytic site exposure was induced by the interfacial crystalline-phase transformation and contributed to the excellent recyclability of the catalyst. This work will provide new insights into the rational design and synthesis of efficient electro-Fenton catalysts with a prominent activity and recyclability.
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