Preparation Of Biochar Research Articles

Biochar design for antibiotics adsorption via a hybrid machine-learning-based optimization framework

Biochar is widely applied as an adsorbent for removing contaminants. Herein, two machine learning (ML) models for biochar preparation and adsorption application were trained based on the eXtreme Gradient Boosting algorithm. Then, the two models were combined by developing a hybrid ML-based optimization framework via Particle Swarm Optimization to design biochar for application requirements. The test determination coefficient for predicting specific surface area (SSA), total volume, and adsorption capacity of biochar were 0.85, 0.88, and 0.97 with root mean square error of 63.10 m2/g, 0.07 cm3/g, and 65.72 μmol/g, respectively. Moreover, SSA was the foremost and positive property of biochar for its adsorption capacity; and pyrolysis temperature and feedstock ash content were the two most important factors affecting SSA, among which the former was positively related and the latter had a negative impact. Optimization results indicated that pine wood pyrolyzed at 500–700 °C could prepare a biochar with higher antibiotic adsorption capacity. This work presents an intelligent strategy to design biochar for adsorbing target pollutants.

A Wooden Carbon-Based Photocatalyst for Water Treatment.

Due to a large number of harmful chemicals flowing into the water source in production and life, the water quality deteriorates, and the use value of water is reduced or lost. Biochar has a strong physical adsorption effect, but it can only separate pollutants from water and cannot eliminate pollutants fundamentally. Photocatalytic degradation technology using photocatalysts uses chemical methods to degrade or mineralize organic pollutants, but it is difficult to recover and reuse. Woody biomass has the advantages of huge reserves, convenient access and a low price. Processing woody biomass into biochar and then combining it with photocatalysts has played a complementary role. In this paper, the shortcomings of a photocatalyst and biochar in water treatment are introduced, respectively, and the advantages of a woody biochar-based photocatalyst made by combining them are summarized. The preparation and assembly methods of the woody biochar-based photocatalyst starting from the preparation of biochar are listed, and the water treatment efficiency of the woody biochar-based photocatalyst using different photocatalysts is listed. Finally, the future development of the woody biochar-based photocatalyst is summarized and prospected.

Exploring the influence of invasive weed biochar on the sorption and dissipation dynamics of imazethapyr in sandy loam soil.

The management of invasive weeds on both arable and non-arable land is a vast challenge. Converting these invasive weeds into biochar and using them to control the fate of herbicides in soil could be an effective strategy within the concept of turning waste into a wealth product. In this study, the fate of imazethapyr (IMZ), a commonly used herbicide in various crops, was investigated by introducing such weeds as biochar, i.e., Parthenium hysterophorus (PB) and Lantana camara (LB) in sandy loam soil. In terms of kinetics, the pseudo-second order (PSO) model provided the best fit for both biochar-mixed soils. More IMZ was sorbed onto LB-mixed soil compared to PB-mixed soil. When compared to the control (no biochar), both PB and LB biochars (at concentrations of 0.2% and 0.5%) increased IMZ adsorption, although the extent of this effect varied depending on the dosage and type of biochar. The Freundlich adsorption isotherm provided a satisfactory explanation for IMZ adsorption in soil/soil mixed with biochar, with the adsorption process exhibiting high nonlinearity. The values of Gibb's free energy change (ΔG) were negative for both adsorption and desorption in soil/soil mixed with biochar, indicating that sorption was exothermic and spontaneous. Both types of biochar significantly affect IMZ dissipation, with higher degradation observed in LB-amended soil compared to PB-amended soil. Hence, the findings suggest that the preparation of biochar from invasive weeds and its utilization for managing the fate of herbicides can effectively reduce the residual toxicity of IMZ in treated agroecosystems in tropical and subtropical regions.

Multifunctional N, Fe dual active site hydrothermal biochar for efficiently degrading paclobutrazol and promoting crop growth

The development of a low-cost, highly catalytic, and soil fertility-improving biochar material is of significant importance for the sustained remediation of organic pollutants in the environment. In this study, multifunctional N, Fe dual active site biochar (NF-BC) was successfully synthesized by hydrothermal method using cotton straw, urea, and FeCl3 as raw materials. Compared to the original biochar, NF-BC exhibits high graphitic-N content and abundant Fe2+, enabling efficient activation of Peroxymonosulfate (PMS) for the removal of Paclobutrazol (PBZ) in water and soil. EPR and quenching experiments confirm that the free radical pathway (•OH) and the non-free radical pathway (1O2) act together in PBZ degradation. The DFT results illustrate the benzene and pyridine rings of PBZ are electron-rich regions, which can be attacked by reactive oxygen species. Then three possible degradation pathways are provided by combining them with the LC/MS test. After remediation by the NF-BC/PMS system, the soil fertility index and plant growth are significantly improved. Compared to CK, the pH value and SOM content of the soil remained unchanged after remediation with the NF-BC/PMS system, while the content of available K and hydrolyzed N increased by 27.18 and 2.27 times, respectively. The pot experiments showed that the NF-BC/PMS system not only alleviates the stress of PBZ on mung bean seedlings, but also promotes an increase in leaf area, accumulation of dry biomass, and root growth. This work provides a new idea for the preparation of low-cost and multifunctional biochar for the efficient removal of pesticides in soil and water environments.

Treatment of aqueous per- and poly-fluoroalkyl substances: A review of biochar adsorbent preparation methods

Per- and poly-fluoroalkyl substances (PFAS) are synthetic chemicals widely used in everyday products, causing elevated concentrations in drinking water and posing a global challenge. While adsorption methods are commonly employed for PFAS removal, the substantial cost and environmental footprint of commercial adsorbents highlight the need for more cost-effective alternatives. Additionally, existing adsorbents exhibit limited effectiveness, particularly against diverse PFAS types, such as short-chain PFAS, necessitating modifications to enhance adsorption capacity. Biochar can be considered a cost-effective and eco-friendly alternative to conventional adsorbents. With abundant feedstocks and favorable physicochemical properties, biochar shows significant potential to be applied as an adsorbent for removing contaminants from water. Despite its effectiveness in adsorbing different inorganic and organic contaminants from water environments, some factors restrict its effective application for PFAS adsorption. These factors are related to the biochar properties, and characteristics of PFAS, as well as water chemistry. Therefore, some modifications have been introduced to overcome these limitations and improve biochar's adsorption capacity. This review explores the preparation conditions, including the pyrolysis process, activation, and modification techniques applied to biochar to enhance its adsorption capacity for different types of PFAS. It addresses critical questions about the adsorption performance of biochar and its composites, mechanisms governing PFAS adsorption, challenges, and future perspectives in this field. The surge in research on biochar for PFAS adsorption indicates a growing interest, making this timely review a valuable resource for future research and an in-depth exploration of biochar's potential in PFAS remediation.

Preparation and modification of Prosopis juliflora biochar and Pb (II) removal from aqueous solutions

Preparation and modification of Prosopis juliflora biochar and Pb (II) removal from aqueous solutions

Synergistic treatment of sewage sludge and food waste digestate residues for efficient energy recovery and biochar preparation by hydrothermal pretreatment, anaerobic digestion, and pyrolysis

The safe disposal of sewage sludge (SS) and food waste digestate residues (DR) is a tough issue considering the difficulty of dewatering and the environmental risks from heavy metals and pathogens. This study combined hydrothermal pretreatment (HP), anaerobic digestion (AD), and pyrolysis to synergistically dispose of SS and DR to enhance dewaterability, recover energy, and prepare biochar with heavy metal immobilization. The results showed that the solid contents of centrifuged cakes increased after HP at 180 °C of SS with the addition of 25% and 50% mass fractions of DR. The centrate from co-HP had a high chemical oxygen demand (COD) and was further treated by AD at 37 °C, producing 193.75 and 210.39 mL/g CODinput (25 °C and 1 atm) of cumulative CH4 under the addition of 50% and 75% mass fractions of DR, respectively. The methanogenic types in AD converted from hydrogen utilization to acetic acid utilization with increasing DR ratio. Zn, Cu, Ni, and Pb were primarily left in the biochar after 50% mass fraction of DR was mixed in the HP combined with pyrolysis at 700 °C; the chemical fractionation of Zn, Cu, Cr, and Pb in the biochar increased to over 85% of the residual fractions, resulting in the lowest potential ecological risk index (15.22, low risk). The CH4 produced from the AD of the co-HP centrate (50: 50, w/w) can supply heat for the HP process, reducing the energy input by 89%. This co-disposal strategy can effectively recover carbon resources from solid wastes to reduce carbon emissions.

Mechanism and application of enhanced degradation of phenol through peroxymonosulfate activation by sulfur-doped biochar prepared with sodium thiosulfate as activator and sulfur dopant

Na2S2O3 was used as activator and sulfur dopant for preparation of sulfur-doped biochar (SBC) with high specific surface area and sulfur content, and its performance to activate peroxymonosulfate (PMS) for phenol degradation was studied. In the presence of 0.3 g/L S4BC-800 and 1 g/L PMS, 20 mg/L phenol could be removed completely in 30 min. S doping improved the electron transfer performance of the composite and enhanced the activation property of PMS for phenol degradation. Free radical quenching experiment and electron paramagnetic resonance analysis indicated that SO4•−, •OH, and 1O2 were involved in phenol degradation. In addition, the current oxidation process confirmed that there was also direct oxidation based on electron transfer between PMS and phenol with S4BC-800 as mediator. The S4BC-800/PMS system could effectively decompose the recalcitrant organic pollutants in the effluent of sewage treatment plant, achieving the total organic carbon removal rate of 83.26 %.

The Influence of Biowaste Type on the Physicochemical and Sorptive Characteristics of Corresponding Biochar Used as Sustainable Sorbent

Biowaste raw materials were used for biochar preparation through pyrolysis at 850 °C under a limited oxygen atmosphere. Raw materials and the corresponding biochar samples were characterized by XRD, FTIR, SEM, TGA, N2-sorption, pH-equilibrium, and ash content measurements. These samples were evaluated as sustainable sorbents for use in methylene blue (MB) removal from artificial fresh water. All biochar samples exhibited high specific surface areas (367–870 m2·g−1), low crystallinity, and low population of functional groups (C–O–C, –COOH, –N–O, –N–H, and –OH) on their surfaces. They were mainly micro-porous materials with a significant fraction of pores in the meso-porous range. The specific surface area of the latter pores proved very important for the physical adsorption of MB from aqueous solution. Although the raw materials exhibited low MB sorption capacity, ranging from 29 to 54 mg·g−1, the corresponding biochar samples exhibited important MB sorption efficiency ranging from 58 to 370 mg·g−1. Among the biochar samples studied, those produced from coffee residues proved most promising for MB removal from water solution (sorption capacity: 280–370 mg·g−1), addressing the United Nations Sustainability Development Goal (SDG) 6: Clean Water and Sanitation by improving the index related to anthropogenic wastewater that has received treatment.

Comparison of methods for activating sesame stalk lignin biochar for removing benzo[a]pyrene from sesame oil

In this study, three activators and two activation methods were employed to activate sesame lignin-based biochar. The biochar samples were comprehensively characterized, their abilities to adsorb benzo[a]pyrene (BaP) from sesame oil were assessed, and the mechanism was analyzed. The results showed that the biochar obtained by one-step activation was more effective in removing BaP from sesame oil than the biochar produced by two-step activation. Among them, the biochar generated by one-step activation with ZnCl2 as the activator had the largest specific surface area (1068.8776 m3/g), and the richest mesoporous structure (0.7891 m3/g); it removed 90.53 % of BaP from sesame oil. BaP was mainly adsorbed by the mesopores of biochar. Mechanistically, pore-filling, π-π conjugations, hydrogen bonding, and n-π interactions were involved. The adsorption was spontaneous and heat-absorbing. In conclusion, the preparation of sesame lignin biochar using one-step activation with ZnCl2 as the activator was found to be the best for removing BaP from sesame oil. This biochar may be an economical adsorbent for the industrial removal of BaP from sesame oil.

Application of machine learning in prediction of Pb2+ adsorption of biochar prepared by tube furnace and fluidized bed.

Data mining by machine learning (ML) has recently come into application in heavy metals purification from wastewater, especially in exploring lead removal by biochar that prepared using tube furnace (TF-C) and fluidized bed (FB-C) pyrolysis methods. In this study, six ML models including Random Forest Regression (RFR), Gradient Boosting Regression (GBR), Support Vector Regression (SVR), Kernel Ridge Regression (KRR), Extreme Gradient Boosting (XGB), and Light Gradient Boosting Machine (LGBM) were employed to predict lead adsorption based on a dataset of 1012 adsorption experiments, comprising 422 TF-C groups from our experiments and 590 FB-C groups from literatures. The XGB model showed superior accuracy and predictive performance for adsorption, achieving R2 values for TF-C (0.992) and FB-C (0.981), respectively. Contrasting inferior results were observed in other models, including RF (0.962 and 0.961), GBR (0.987 and 0.975), SVR (0.839 and 0.763), KRR (0.817 and 0.881), and LGBM (0.975 and 0.868). Additionally, a hybrid dataset combining both biochars in Pb adsorption also indicated high accuracy (0.972) as obtained from XGB model. The investigation revealed that the influence of char characteristics and adsorption conditions on Pb adsorption differs between the two biochar. Specific char characteristics, particularly nitrogen content, significantly influence lead adsorption in both biochar. Interestingly, the influence of pyrolysis temperature (PT) on lead adsorption is found to be greater for TF-C than for FB-C. Consequently, careful consideration of PT is crucial when preparing TF-C biochar. These findings offer practical guidance for optimizing biochar preparation conditions during heavy metal removal from wastewater.

Recent Advances in the Preparation and Application of Biochar Derived from Lignocellulosic Biomass: A Mini Review.

With the rapid growth in the global population and the accelerating pace of urbanization, researching and developing novel strategies for biomass utilization is significant due to its potential for use in renewable energy, climate change mitigation, waste management, and sustainable agriculture. In this environmental context, this review discusses the recent advances in biomass conversion technologies for biochar production, including the first carbonization process and the subsequent activation methods of the biochar derived from lignocellulosic biomass (LBC). Parallel to this, this review deals with other essential parameters in biochar production, such as feedstock types, reaction environments, and operating conditions in the pyrolysis process, to determine the production and composition of LBC. Moreover, the wide-ranging applications of LBC in areas such as adsorption, catalysts, and energy storage are discussed, offering sustainable and environmentally friendly alternatives while reducing reliance on traditional energy sources and mineral resources, thereby providing practical solutions to environmental and energy challenges. Overall, this review not only provides a comprehensive comparative analysis of different LBC preparation methods, but also facilitates a deeper understanding of the advantages and limitations of these methodologies when it comes to developing high-value materials for sustainable applications.

Norfloxacin adsorption by torrefied coco peat biochar as a novel adsorbent in a circular economy framework

The current study reported torrefied coco-peat biochar treated at 200 °C, as a novel adsorbent exhibiting phenomenal norfloxacin (NFX) adsorption efficiency. The CHNS analysis confirmed the carbon abundance in the biochar (36.45%), however, XRF analysis indicated a significant presence of K2O (27.73%) and chlorine (7.49%). The XRD and Raman spectral analysis confirmed the amorphous structure of the biochar. Multilayer topology was evident in the SEM micrograph of biochar contributing to its large effective surface area. Additionally, the mesoporous structure of the adsorbent was verified by BET. The adsorption mechanism was predicted to be non-ionic since the zeta potential of both adsorbent and adsorbate was found negative. The process parameters were optimized at 30 °C, pH 6.9, dosage 7 g/L, antibiotic load 494.25 mg/L, and time of 89 min for a maximum of 99.52% adsorption of NFX using Central Composite Design, Analysis of Variance, and Response Surface Methodology. The adsorption process was exothermic, and spontaneous obeying the pseudo-second-order kinetics, while the bulk process was confined to surface adsorption. Isotherm study of NFX adsorption revealed the process to be a favorable, monolayer, and homogeneous adsorption. The NFX molecules were desorbed with an efficiency of 89.19% using 80% ethanol and upon recrystallization, 87.76% of the initial NFX was recovered as crude crystal. Moreover, the NFX removal efficiency was consistent across various water systems, tap water (99.02%), seawater (99.56%), river water (98.92%), pond water (98.26%), and distilled water (99.17%). The techno-economic analysis identified bulk expense as the biochar preparation ($0.82/kg) and the process will be profitable having recovered NFX sold at $6/kg instead of the present retail price ($71/kg). Thus, the study successfully demonstrated a zero-waste, self-sustainable, and revenue-generating water treatment process implementing the circular economy framework.

Preparation of iron oxide-modified digestate biochar and effect on anaerobic digestion of kitchen waste

Two kinds of Fe2O3-modified digestate-derived biochar (BC) were prepared and their effects on anaerobic digestion (AD) of kitchen waste (40.0 g VS/L) were investigated, with BC and Fe2O3 addition used as a comparison. The results showed that Fe2O3-modified BC (Fe2O3-BC1 prepared by co-precipitation and Fe2O3-BC2 by impregnation) significantly increased methane yield (20.8 % and 16.4 %, respectively) and reduced volatile fatty acid concentration (35.6 % and 29.6 %, respectively). Microbial high-throughput analysis revealed that Fe2O3-modified BC selectively enriched Clostridium (47.3 %) and Methanosarcina (72.2 %), suggesting that direct interspecies electron transfer contributing to improved biogas production performance was established and enhanced. Correlation analysis indicated that biogas production performance was improved by the larger specific surface area (83.4 m2/g), pore volume (0.101 cm3/g), and iron content (97.4 g/Kg) of the BC. These results offer insights for enhancing the efficacy of AD processes using Fe2O3-modified BCs as additives.

Preparation and Modification of Biochar Derived from Agricultural Waste for Metal Adsorption from Urban Wastewater

This work evaluates the efficiency of three biochar samples toward the adsorption of manganese, iron, and selenium present in a sample of urban wastewater. The biochar was produced from the pyrolysis of rice husks at 350 °C for 6 h (RHB) and subsequently modified using HCl (RHBHCl) or NaOH (RHBNaOH) to increase its surface area. The RHBNaOH sample exhibited the highest removal efficiency for the three metals. The metals’ adsorption removal efficiency for RHBNaOH was in the order Mn (76%), Se (66%), and Fe (66%), while for RHBHCl, it was Fe (59%), Mn (30%), and Se (26%). The results show that the as-prepared RHB can remove the metals, even if in low amounts (Fe (48%), Mn (3%), and Se (39%)). The adsorption removal for the three types of adsorbents follows the Langmuir isotherm model. Pseudo-first-order and pseudo-second-order models were used to determine the adsorption mechanism for each of the three adsorbents. Both models showed a good fit with R2 (>0.9) for the RHBNaOH and RHB sorption of Fe, Mn, and Se. Overall, this work demonstrates the potential of biochar for the removal of metals from real wastewater.

Efficient Adsorption of Nitrogen and Phosphorus in Wastewater by Biochar.

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption.

Machine learning in clarifying complex relationships: Biochar preparation procedures and capacitance characteristics

Supercapacitors as a new type of energy storage device play an important role in the development of renewable energy. Activated biochar-based electrode materials has good energy storage potential because of useful physicochemical properties and renewability. The optimal preparation method for biochar-based electrodes for supercapacitors is difficult to determine experimentally due to the complexity of influencing factors. Therefore, three machine learning models were developed to describe the relationship between the preparation process and the energy storage characteristics of activated biochar. The Gradient Boosting Regression (GBR) model provided the best prediction, with an R2 value of 0.93. Interestingly, the heating rate was the most important factor affecting the specific capacitance of activated biochar and showed a significant negative correlation, with a feature importance of 35.08 %. In addition, Micropore volume proportion and specific surface area showed a significant positive correlation with specific capacitance, with feature importance of 15.39 % and 9.23 %, respectively. Significantly, the specific capacitance could be improved by increasing the added amount of N source and activator and a higher activation temperature, as well as using a shorter activation time and slower heating rate during preparation. This study provides new insights into the applications of activated biochar for energy storage through data analysis.

Sulfuric acid-assisted ball milling for the preparation of Si-O-enriched straw biochar: removal efficiency of rhodamine B and adsorption mechanism.

Traditional pyrolysis biochar has been widely employed to treat dye wastewater. However, there are some problems in the pyrolysis process, such as the generation of harmful gases and the low content of silico-oxygen functional groups to promote adsorption. Straw biochar (Ac-BCbm) was prepared by sulfuric acid co-ball milling method. The adsorption performance and adsorption mechanism of rhodamine B (RhB) under different preparation conditions and factors were investigated. The results showed that the adsorption rate of Ac-BCbm on RhB was up to 94.9%, which was 60.5% and 55.8% higher than that of ball-milling straw (STbm) and biochar prepared by pyrolysis (STBC600), respectively. The Ac-BCbm had better adaptability under different pH and common interfering ions for remove RhB. Characterization and DFT simulation analysis revealed that the sulfuric acid co-ball milling process promoted the formation of Si-OH and Si-O-CH3 oxygen-containing functional groups of Si component in straw, which enhanced the hydrogen bonding interactions and effectively improved the adsorption efficiency. This study investigated a new strategy for biochar preparation by sulfuric acid co-ball milling, which provides an additional development direction for the efficient resource utilization of straw.

An efficient and general oxidative magnetization for preparation of versatile magnetic porous biochar at low temperature

Oxidative magnetization is an emerging method for manufacturing versatile magnetic biochar at comparatively low pyrolysis temperature, benefiting to reducing functional groups decomposition with low energy consume. A magnetic porous biochar was manufactured by a novel oxidative magnetization [KMnO4/Fe2(SO4)3 accelerated pyrolysis of kelp at 300 °C] for removing three kinds of contaminants from aqueous solution. Spherical nanoscale Fe3O4 was massively doped with introduction of oxygen functional groups simultaneously. Remarkable increase of surface area and pore volume was also observed. Benefiting from these factors, remarkably increased adsorption capability and saturation magnetization were achieved. The magnetic biochar possessed 145.71, 72.58, and 322.48 mg/g maximum adsorption amounts for Cr6+, methylene blue, and tetracycline with 17.11 emu/g saturation magnetization, respectively, in which nanoscale iron oxides and oxygen functional groups made significant contributions. Furthermore, KMnO4/Fe2(SO4)3 accelerated pyrolysis showed superior generality for fabricating high-performance magnetic biochars using diverse bio-wastes at low temperature.

Preparation of Mn-doped sludge biochar and its catalytic activity to persulfate for phenol removal.

In recent years, the increasing prevalence of phenolic pollutants emitted into the environment has posed severe hazards to ecosystems and living organisms. Consequently, there is an urgent need for a green and efficient method to address environmental pollution. This study utilized waste sludge as a precursor and employed a hydrothermal-calcination co-pyrolysis method to prepare manganese (Mn)-doped biochar composite material (Mn@SBC-HP). The material was used to activate peroxydisulfate (PDS) for the removal of phenol. The study investigated various factors (such as the type and amount of doping metal, pyrolysis temperature, catalyst dosage, PDS dosage, pH value, initial phenol concentration, inorganic anions, and salinity) affecting phenol removal and the mechanisms within the Mn@SBC-HP/PDS system. Results indicated that under optimal conditions, the Mn@SBC-HP/PDS system achieved 100% removal of 100mg/L phenol within 180min, with a TOC removal efficiency of 82.7%. Additionally, the phenol removal efficiency of the Mn@SBC-HP/PDS system remained above 90% over a wide pH range (3-9). Free radical quenching experiments and electron spin resonance (ESR) results suggested that hydroxyl radicals (·OH) and sulfate radicals (SO4-) yed a role in the removal of phenol through radical pathways, with singlet oxygen (1O2) being the dominant non-radical pathway. The phenol removal efficiency remained above 90%, demonstrating the excellent adaptability of the Mn@SBC-HP/PDS system under the interference of coexisting inorganic anions or increased salinity. This study proposes an innovative method for the resource utilization of waste, creating metal-biochar composite catalysts for the remediation of water environments. It provides a new approach for the efficiency of organic pollutants in water environments.