Biochar-based Catalysts Research Articles

Insight into enhanced tetracycline photodegradation by hematite/biochar composites: Roles of charge transfer, biochar-derived dissolved organic matter and persistent free radicals.

The combination of hematite and biochar significantly accelerated tetracycline (TC) removal under visible light irradiation. The kinit of TC removal with Hem/BC-5 reached 0.103 min-1, 3.8 and 6.1 times faster than those with hematite and biochar, attributed to boosting free radicals. The enhanced light absorption and charge transfer helped generate more H2O2 and •OH through 2e- oxygen reduction and direct valence band (VB) oxidation. Persistent free radicals (PFRs) on biochar helped generate H2O2. Biochar as electron shutter facilitated Fe3+/Fe2+ redox cycling and triggered more efficient photo-Fenton reaction. Biochar-derived dissolved organic matter (DOM) helped generate 3DOM*, a reactive intermediate to produce H2O2, •OH, and 1O2. Hem/BC composites have excellent photoactivity for the degradation of TC in different water matrixes under visible light irradiation. The degradation pathway was proposed based on theoretical calculation and detected degradation intermediates. These findings contribute to the development of biochar-based catalysts for organic pollutants removal.

Catalytic conversion of the heavy fraction of bio-oil into phenol-rich oils using an Fe-carbon catalyst during straw pyrolysis

This study examines the catalytic cracking of the heavy fraction of bio-oil to produce phenol-rich oils, emphasizing the enhancement of biochar-based catalysts through the incorporation of metallic iron (Fe) species. Results indicate that the Fe-carbon catalyst significantly enhances the conversion of heavy oil constituents into phenolic compounds, increasing the relative content of phenolics from 41 % to over 76 %, compared to unenhanced co-pyrolysis, which primarily yielded methylphenols, phenol, 2-methylphenol, and 3-methylphenol. These findings suggest that the heavy fraction of bio-oil, typically abundant in macromolecular compounds, offers viable opportunities for the targeted production of phenolic oils utilizing Fe-carbon catalysts. The findings suggest a viable pathway for the conversion of bio-oil heavy fractions into valuable phenolic compounds, highlighting the potential for industrial applications and the optimization of biorefinery processes.

Enhanced sulfamethoxazole degradation in aqueous media using a synergistic system with dielectric barrier discharge plasma, biochar-enriched iron concentrate, and persulfate

The synthesis of biochar-based catalysts from bamboo strip biomass waste aligns with the principles of environmental sustainability and recycling. This study focuses on the degradation of sulfamethoxazole (SMX) in a simulated aqueous environment. A composite catalyst (IC–BC) was prepared by impregnating bamboo strip biochar (BC) with iron concentrates (IC). The optimal configuration for the oxidative degradation of SMX was achieved using IC-BC-activated persulfate (PS). The structural, morphological, optical, and electrochemical properties of the IC-BC were thoroughly characterized, revealing its robust stability through repeated cycles. The dielectric barrier discharge (DBD) synergistic IC-BC/PS oxidation system demonstrated an SMX degradation efficiency of 93.33 % in 10 min. Quenching experiments and electron paramagnetic resonance (EPR) spectroscopy identified radicals O•−2, •OH, and SO•−4 radicals as the primary active species involved in the degradation process. Ultraviolet-visible absorption spectroscopy (UV–Vis) confirmed this synergistic effect. Liquid chromatography mass spectrometry (LC-MS) identified four potential SMX degradation pathways. Total Organic Carbon (TOC) elimination efficiency tests and toxicological analyses revealed that the intermediates were significantly less toxic than SMX. These results demonstrate that the DBD/IC-BC/PS system significantly enhances the removal efficiency of SMX, offering excellent environmental protection properties.

Magnetic MgFeO@BC Derived from Rice Husk as Peroxymonosulfate Activator for Sulfamethoxazole Degradation: Performance and Reaction Mechanism.

Heterogeneous Mg-Fe oxide/biochar (MgFeO@BC) nanocomposites were synthesized by a co-precipitation method and used as biochar-based catalysts to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. The optimal conditions for SMX degradation were examined as follows: pH 7.0, MgFeO@BC of 0.4 g/L, PMS concentration of 0.6 mM and SMX concentration of 10.0 mg/L at 25 ℃. In the MgFeO@BC/PMS system, the removal efficiency of SMX was 99.0% in water within 40 min under optimal conditions. In the MgFeO@BC/PMS system, the removal efficiencies of tetracycline (TC), cephalexin (CEX), ciprofloxacin (CIP), 4-chloro-3-methyl phenol (CMP) and SMX within 40 min are 95.3%, 98.4%, 98.2%, 97.5% and 99.0%, respectively. The radical quenching experiments and electron spin resonance (ESR) analysis suggested that both non-radical pathway and radical pathway advanced SMX degradation. SMX was oxidized by sulfate radicals (SO4•-), hydroxyl radicals (•OH) and singlet oxygen (1O2), and SO4•- acted as the main active species. MgFeO@BC exhibits a higher current density, and therefore, a higher electron migration rate and redox capacity. Due to the large number of available binding sites on the surface of MgFeO@BC and the low amount of ion leaching during the catalytic reaction, the system has good anti-interference ability and stability. Finally, the intermediates of SMX were detected.

Co-pyrolyzed biochar derived from microplastics and microalgae as peroxymonosulfate activator: Influence of microplastic types and analysis of systemic causes

This work investigated the catalytic activity of co-pyrolyzed biochar (MP-SBC) from microplastic (MP) and Spirulina biomass and its activation mechanism for peroxymonosulfate (PMS). Given that different types of MPs had varied effects on the properties of biochar, polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polylactic acid (PLA) were chosen as MP feedstocks. The results showed that the four kinds of MP-SBCs activated PMS more efficiently than the pristine algal-based biochar (SBC), with 100 % of the acetaminophen (ACT) degraded within 20 min. Based on the reaction mechanism analysis, the main pathways for the degradation of ACT by SBC and MP-SBC activated PMS were both non-radical pathways, and ACT was also efficiently degraded by the synergistic effect of 1O2 and electron transport pathway (ETP). Moreover, it was found that the microplastic modification could significantly enhance the efficacy of SBCs in triggering the non-radical pathway. Establishing the correlation between the structural features of BC and the degradation mechanism (active species contribution) revealed that the persistent free radicals (PFRs), defective structures, CO, and graphite N are all potential active sites. Thereinto, PFRs are the active sites for radicals, defects are the active sites for 1O2 production, and CO, defects, and graphitic N are the active sites for ETP. Overall, this work provides an innovative approach for designing efficient biochar-based catalysts for environmental remediation.

Peroxymonosulfate Activation by Rice-Husk-Derived Biochar (RBC) for the Degradation of Sulfamethoxazole: The Key Role of Hydroxyl Groups.

In this work, rice-husk-derived biochar (RBC) was synthesized by using simple one-step pyrolysis strategies and served as catalysts to activate peroxymonosulfate (PMS) for degrading sulfamethoxazole (SMX). When the annealing temperature (T) = 800 °C, RBC800 exhibits the typical hardwood structure with several micropores and mesoporous. Furthermore, RBC800 obtains more defect sites than RBC600, RBC700, and RBC900. In the RBC800/PMS system, the removal rate of the SMX reached 92.0% under optimal conditions. The kinetic reaction rate constant (kobs) of the RBC800/PMS system was 0.009 min-1, which was about 1.50, 1.28, and 4.50 times that of the RBC600/PMS (kobs = 0.006 min-1), RBC700/PMS (kobs = 0.007 min-1), and RBC900/PMS (kobs = 0.002 min-1) systems, respectively. In the RBC800/PMS system, sulfate radical (SO4•-) is the main active species. Compared with other active sites, the hydroxyl group (C-OH) on the surface of RBC800 interacts more strongly with PMS, which is more likely to promote the stretching of the O-O bond of the PMS, thus breaking into the activated state and significantly reducing the activation energy required for reaction. The degradation intermediates of SMX were speculated, and the toxicity analysis was conducted. Generally, this work reveals in depth the interaction between reactive sites of biochar-based catalysts and PMS at the molecular level.

Optimizing macroalgal biochar-based catalysts for monophenols recovery during wood dust catalytic pyrolysis: A comparative study using response surface methodology and artificial neural network

This study aimed to explore the optimization of macroalgal biochar-based catalysts (MBBCs) for enhanced monophenolic production in biomass pyrolysis. By utilizing response surface methodology (RSM) and artificial neural network (ANN), key variables in the activation process during preparation of MBBCs were identified including activation temperature, activator ratio, and CO2 residence time. The results showed that the ANN model, with an R2 of 0.9816, accurately predicted optimal catalyst activation conditions, closely matching the experimentally determined optimal conditions (ENPC800-1:2–30). The bio-oil yield decreased under ENPC800-1:2–30 catalyst, but the monophenolic content increased significantly, reaching a relative content of 60 %, with a total concentration of phenol, cresols, and ethylphenol amounting to 35.54 mg/gbio-oil. The present study revealed significant changes in non-condensable gas composition, including increased hydrogen and carbon monoxide which aid in enhancing their energy applications. Thus, the optimized MBBCs greatly help in improving the bio-oil and non-condensable gas quality and thereby providing vital insights over sustainable chemical production through biomass pyrolysis.

Viscosity reduction of heavy oil based on rice husk char-based nanocatalysts of NiO/Fe2O3

In recent years, catalytic hydrothermal cracking has gained significant attention as an effective technology for reducing the viscosity of heavy oil in the field of heavy oil recovery. However, the current catalyst temperature window is relatively high, leading to high energy consumption in heavy oil extraction. The development of catalysts that can effectively reduce the viscosity of heavy oil at low temperatures is important to reduce energy consumption in the thermal recovery process of heavy oil. Biochar-based catalysts exhibit good low-temperature activity. Therefore, this study used modified rice husk char as a carrier to develop NiO-RHC, Fe2O3-RHC, and NiO/Fe2O3-RHC catalysts, and investigated their performance in low-temperature catalytic viscosity reduction. Various methods were used to characterize the physical and chemical properties of the catalysts, and the effects of catalyst type and addition amounts on the catalytic viscosity reduction reaction were examined. The results showed that the catalytic performance of the dual-active component catalyst was better than that of NiO-RHC and Fe2O3-RHC. Under the catalysis of NiO/Fe2O3-RHC, the viscosity of heavy oil decreased by 81.81 %. As the catalyst addition amounts increased, the viscosity reduction rate of heavy oil also increased. The optimal catalyst addition amount was 1.00 wt%, and the heavy component content in the oil sample was reduced by 4.14 % after the catalytic reaction. Finally, the mechanism of heavy oil viscosity reduction was analyzed. It was found that the breaking of C-S bonds was a significant factor in reducing heavy oil viscosity, and the S in H2S mainly came from thioether and sulfoxide sulfur. This study provides valuable references for further research on low-temperature viscosity reduction in heavy oil.

In-situ and ex-situ selective catalysis of biochar-based catalysts for the production of high-quality bio-oil and H2-rich gas from tobacco stem

Optimizing the catalytic pyrolysis process is a promising approach to enhance the quality of the resulting products. Thus, four metals (Ni, Fe, Co, Cu) were loaded on biochar support to prepare biochar-based catalysts, and the mechanism of its effect on quality improvement of bio-oil and pyrolysis gas during in-situ and ex-situ pyrolysis of tobacco stem was investigated. The results showed that the biochar-based catalyst has high selectivity for H2-rich and phenols production during in-situ pyrolysis, while the phenols content reached 57.99 % and H2 content reached 49.91 % in Fe@BC group. It is highly selective to H2-rich and N-containing compounds during ex-situ pyrolysis, and the content of N-containing compounds reached 47.23 % and the content of H2 reached 47.59 % in the Ni@BC group. This contributes to the efficient use of high-quality bio-oils and the production of clean gases. Biochar-based catalysts hold significant potential for the pyrolysis industry, paving the way for large-scale production and application of high-quality pyrolysis products.

Role of biochar as a greener catalyst in biofuel production: Production, activation, and potential utilization – A review

BackgroundBiochar is an affordable carbonaceous product produced through a combination of thermochemical conversion processes using organic feedstock in the absence or constrained supply of oxygen. Biochar-based catalysts are promising in numerous catalytic applications for sustainable bioenergy production. MethodsHydrothermal carbonization, gasification, and pyrolysis are conventional biochar production techniques. The biochar must be activated to improve its physiochemical characteristics. The activation is generally classified into three types: physical, chemical, and impregnation. The biochar-based catalysts are categorized into different types, such as pristine, heteroatom-doped, metal-loaded, magnetic, and nanometallic oxide/hydroxide biochar. Significant findingsThese biochar-based catalysts effectively catalyze various biochemical reactions and are extensively used in biofuel production. This article extensively explores various biochar production and activation strategies and their applications as a catalyst for biofuel production. Activated biochar with improved surface properties has a high surface area and adaptable surface chemistry, making it a sustainable alternative to conventional catalysts. Biochar from renewable biomass has advantages in waste management, carbon sequestration, and reduced greenhouse gas emissions. Further research and innovation using nanomaterials, artificial intelligence, and machine learning are needed to utilize biochar as a sustainable and potential green catalyst for advanced biofuel production.

Catalyst breakthroughs in methane dry reforming: Employing machine learning for future advancements

Rising levels of atmospheric carbon dioxide (CO2) and methane (CH4) have sparked the interest of researchers in resolving this issue. Various technologies have been utilized such as dry reformation of methane (DRM), that turns these greenhouse gases (GHGs) into syngas. Numerous studies have been done in recent years to produce efficient and competitive catalysts for DRM. However, a “state of the art” review is still required due to a lack of literature on improvements and scalability of robust catalytic systems. This study aims to evaluate recent advancements in catalyst formulations, their activities, stability, and selectivity. We have discussed a variety of materials, including Metal-Organic Frameworks (MOF), a type of two-dimensional transition metal carbides and nitrides (MXene), reducible and irreducible metal oxides, transition metal oxides, zeolites, carbon, and biochar-based catalysts, which are responsible for improving the effectiveness of the DRM process. Furthermore, machine learning (ML) approaches are highlighted for their potential in catalyst design and optimization, providing increased accuracy and efficiency. This review highlights major enhancements to the DRM method, which result in higher hydrogen yield and catalyst stability. Novel catalysts have been created to tackle crucial problems including coking and sintering, which are necessary to progress commercialization. To ensure successful commercial application, future research should concentrate on finding catalysts with excellent features that are also economically viable. This study provides a significant resource for future catalyst development and promotes greater cooperation between academic and commercial communities.

Enhancement of hydrogen-rich gas production by acetic acid steam reforming: characterization of Ni–Co modified biochar-based catalysts

Abstract The development of cost-effective and highly efficient biochar-based catalysts is essential for the catalytic steam reforming process of bio-oil. In this study, pickling peanut shell biochar was used to prepare biochar-supported Ni/Co monometallic catalyst and biochar-supported nickel-Co bimetallic catalyst through the impregnation method. The catalytic effect of these catalysts on acetic acid (a bio-oil model compound) steam reforming was investigated. It was found that Co could enhance the dispersion of metal particles. The catalyst exhibited the best catalytic effect and significantly improved resistance to carbon deposition with a loading of 8 wt% and a Ni-to-Co ratio of 6:2. At the temperature of 600 °C and the S/C ratio of 3, the selectivity of H2 reached 84.48 %, and the conversion of acetic acid reached 95.49 %. A synergistic effect was observed between Ni and Co, leading to increased metal dispersion, enhanced reducibility, and a higher number of active centers. Co facilitates water dissociation and promotes the oxidation of C–H and mobile O, resulting in a faster decarbonization rate. The effective utilization of biochar-based catalysts and the rational utilization of bio-oil contribute to the timely achievement of carbon emission reduction targets.

Visible light-assisted activation of peroxymonosulfate for naproxen degradation with biochar-based catalysts: Sandwich structure construction and synergy of free and non-free radicals

Visible light-assisted activation of peroxymonosulfate for naproxen degradation with biochar-based catalysts: Sandwich structure construction and synergy of free and non-free radicals

Sustainability of biomass pyrolysis for bio-aromatics and bio-phenols production: Life cycle assessment of stepwise catalytic approach

The high-valued utilization of biomass resources remains challenging due to their complex biochemical compositions and limited product selectivity. Herein, we propose a novel biomass stepwise catalytic pyrolysis process to efficiently produce aromatic hydrocarbons and phenols by leveraging the distinct thermal stability of biomass components and their compatibility with ZSM-5 and biochar-based catalysts. A life cycle assessment (LCA) is conducted to evaluate the energy consumption and environmental impact of this innovative process compared to conventional methods. Our findings reveal that this approach significantly reduces the energy consumption by 51.76–90.02 % across different application scenarios of by-product biochar. Additionally, using biochar as a soil amendment contributes to carbon negativity, achieving a net greenhouse gas (GHG) emission reduction of up to 6 t CO2 eq for producing 8.325 t aromatics and 1 t phenol. The first-stage catalytic pyrolysis for producing aromatic hydrocarbons is identified as the major contributor to environmental impact, mainly due to ZSM-5 catalyst usage and loss, while the second stage for phenol production has a comparatively minor impact. Finally, sensitivity analysis of the key parameters highlights areas for process optimization, including reducing catalyst dosage, minimizing energy consumption, and improving phenol yield, which are crucial for enhancing the environmental and economic viability of the entire route. This study provides a detailed LCA and offers insights for future improvements in biomass conversion technology.

Activation preference: A new descriptor to predict non-radical oxidation pathways

The peroxymonosulfate (PMS) activation was influenced strongly by active sites on a catalyst surface. To some extent, biochar characters, such as structure, elemental composition, and specific surface area (SSA), can reflect the composition of active sites. However, the understanding of active centers lacked accuracy in the structure–activity relationships of biochar-based catalysts (BBC) due to the consideration of one single feature. In this study, XGBoost (XGB), random forest regression (RF), and supporting vector regression (SVR) models were employed to construct descriptors to predict non-radical (NR) contribution in BBC/PMS systems. Consequently, the XGB model provided the best prediction with an R2 value of 0.81. Thereby, activation preference (γ), as a characteristic descriptor of BBC, was developed using the XGB model. Interestingly, the descriptor fully considered carbon content (C%), oxygen content (O%), defects (ID/IG), and SSA. Besides, O% played the most critical role in predicting NR contribution. Noticeably, the NR oxidation pathway could be promoted within the range of 50–60 % for C%, 30–50 % for O%, 0.4–1.2 for ID/IG, and 579–1259 m2/g for SSA in the BBC/PMS system. Herein, machine learning (ML) was applied to develop a comprehensive descriptor, further providing an innovative strategy for high-throughput screening of BBCs to activate PMS efficiently. The comprehensive descriptor offered a new perspective for elucidating the structure–activity relationship of BBC, facilitating the application of BBC/PMS systems in water treatment.

Optimization of Photothermal Catalytic Reaction of Ethyl Acetate and NO Catalyzed by Biochar-Supported MnOx-TiO2 Catalysts.

The substitution of ethyl acetate for ammonia in NH3-SCR provides a novel strategy for the simultaneous removal of VOCs and NO. In this study, three distinct types of biochar were fabricated through pyrolysis at 700 °C. MnOx and TiO2 were sequentially loaded onto these biochar substrates via a hydrothermal process, yielding a family of biochar-based catalysts with optimized dosages. Upon exposure to xenon lamp irradiation at 240 °C, the biochar catalyst designated as 700-12-3GN, derived from Ginkgo shells, demonstrated the highest catalytic activity when contrasted with its counterparts prepared from moso bamboo and loofah. The conversion efficiencies for NO and ethyl acetate (EA) peaked at 73.66% and 62.09%, respectively, at a catalyst loading of 300 mg. The characterization results indicate that the 700-12-3GN catalyst exhibits superior activity, which can be attributed to the higher concentration of Mn4+ and Ti4+ species, along with its superior redox properties and suitable elemental distribution. Notably, the 700-12-3GN catalyst has the smallest specific surface area but the largest pore volume and average BJH pore size, indicating that the specific surface area is not the predominant factor affecting catalyst performance. Instead, pore volume and average BJH pore diameter appear to be the more influential parameters. This research provides a reference and prospect for the resource utilization of biochar and the development of photothermal co-catalytic ethyl acetate and NO at low cost.

Activation of persulfate by biochar-based catalysts for elimination of refractory organic pollutants: a review

Activation of persulfate by biochar-based catalysts for elimination of refractory organic pollutants: a review

Engineered biochar-based catalytic pyrolysis of Spirulina plantensis microalgae for the production of high value compounds in microwave reactor

Energy demands are continually increasing as a result of population growth and industrialization, prompting the completion of new research to examine biochar-based catalytic pyrolysis of Spirulina plantensis (SP) microalgae for the generation of high-value chemicals in a microwave reactor. Biochar-based catalysts have excellent microwave absorption, a porous structure, and high catalytic activity, making them ideal for microwave-induced biomass pyrolysis. Initially, raw biomass, biochar, and Zn-BC were characterized based on XRD, FTIR, nitrogen adsorption-desorption and SEM-EDS analysis to determine the phases, functional groups, BET surface area and morphology, respectively. The thermogravimetric analysis results demonstrated the favourable impact of Zn-BC by displaying a drop in the reaction's temperature requirements. The kinetic study revealed that catalytic pyrolysis has a lower activation energy (27.62 kJ/mol) than non-catalytic pyrolysis (32.99 kJ/mol). FTIR measurement of the bio-oil indicated that at particular peak positions, intensity has changed or disappeared. The GCMS results revealed a significant reduction in the nitrogen-containing (19 %) chemicals at the same time increase in acidic chemicals for the catalytic bio-oil.

Application of Biochar-Based Catalysts for Soil and Water Pollution Control

Application of Biochar-Based Catalysts for Soil and Water Pollution Control

Catalytic pyrolysis of wood dust for monophenol over macroalgal biochar-based catalyst: Effects of activation agents and atmospheres during catalyst synthesis on its performance

After introducing heteroatoms into the carbon material skeleton, the performance of carbocatalyst during catalytic pyrolysis of biomass for monophenol production is significantly improved. Algae, as a carbon source with intrinsic nitrogen content, is well-identified as a suitable raw material for preparing heteroatom-doped carbocatalyst. The present study aimed to investigate the effects of different alkaline activation agents (KOH/NaOH) and gas atmospheres (N2/CO2) during the carbonization-activation synthesis process of macroalgal biochar-based catalysts (MBBCs) on their properties and performances. Characterizations of carbocatalysts were carried out via BET and XPS analyses to investigate the porous structures and surface functional groups. Results showed that CO2, as a weakly oxidizing atmosphere, can promote the formation of porous structure of MBBCs. However, the promotion is not as strong as that of chemical activation agents (KOH/NaOH). Furthermore, KOH can promote the formation of porous structure more strongly than NaOH, but NaOH can substantially enhance the formation of surface oxygen‑nitrogen groups compared to KOH. All the MBBCs exhibited the increment of monophenols in the bio-oil obtained from catalytic pyrolysis of wood dust, especially phenol, o-cresol, and p-cresol. Amongst, the biochar-based catalyst activated with NaOH in CO2 atmosphere was the most effective one in promoting monophenols content (up to 59.46 %). Compared with the control group (without catalyst), the phenol content was increased from 5.03 % to 19.40 %. Moreover, it is found that the catalytic performance was positively correlated with the CO species percentage on the surface of MBBCs. The macroalgal biochar-based catalyst has an excellent catalytic performance, which is of great significance for achieving the complete utilization of algae and thereby improving the quality of catalytic pyrolysis products.