Surface Area Of Biochar Research Articles

Development of a novel three-dimensional biofilm-electrode system (3D-BES) loaded with Fe-modified biochars for enhanced pollutants removal in landfill leachate

Different mass ratio iron (Fe)-loaded biochars (FeBCs) were prepared from food waste and used in the three-dimensional biofilm-electrode systems (3D-BES) as particular electrodes for landfill leachate treatment. Compared to the unmodified biochar (BC), specific surface area of Fe-loaded biochars (FeBC-3 with a Fe: biochar of 0.2:1) increased from 63.01 m2/g to 184.14 m2/g, and pore capacity increased from 0.038 cm3/g to 0.111 cm3/g. FeBCs provided more oxygen-containing functional groups and exhibited excellent redox properties. Installed with FeBC-3 as particular electrode, both NH4+-N and chemical oxygen demand COD removals in 3D-BESs were well fitted with the pseudo-first-order model, with the maximum removal efficiencies of 98.6 % and 95.5 %, respectively. The batch adsorption kinetics experiments confirmed that the maximum NH4+-N (7.5 mg/g) and COD (21.8 mg/g) adsorption capacities were associated closely with the FeBC-3 biochar. In contrast to the 3D-BES with the unmodified biochar, Fe-loaded biochars significantly increased the abundance of microorganisms being capable of removing organics and ammonia. Meanwhile, the increased content of dehydrogenase (DHA) and electron transport system activity (ETSA) evidenced that FeBCs could enhance microbial internal activities and regulate electron transfer process among functional microorganisms. Consequently, it is concluded that Fe-loaded biochar to 3D-BES is effective in enhancing pollutant removals in landfill leachate and provided a reliable and effective strategy for refractory wastewater treatment.

Degradation of 2,4-DCP by immobilized laccase on modified biochar carrier.

Rape straw was used as the raw material for the biochar in this study, which was then changed using acid, alkali, and magnetic techniques. The laccase was attached using the adsorptions-crosslinking process, and the three modified biochars served as the carriers. The ideal circumstances for laccase immobilization were explored, and both biochar and immobilized laccase's characteristics were examined. The removal of 2,4-dichlorophenol (2,4-DCP) by immobilized laccase from modified biochar and its degradation products were researched. The main conclusions are as follows: the optimal concentration of glutaraldehyde (GLU) was 4%, and the pH was four, and the enzyme dosage was 1.75mg/mL for the immobilized laccase of acid-modified biochar (SBC@LAC). The optimal concentration of GLU was 5%; the pH was four, and the enzyme dosage was 2mg/mL for immobilized laccase from alkali-modified biochar (JBC@LAC). The optimal concentration of GLU was 5%; the pH was four, and the enzyme dosage was 1.75mg/mL for immobilized laccase from magnetically modified biochar (CBC@LAC). SEM images could show the changes in the surface morphology of biochar caused by three modification methods. The BET results demonstrated that acid and magnetic modification increased the specific surface area of biochar, and alkali modification mainly expanded the pore size of biochar. FT-IR and XRD showed that modification and laccase loading had little effect on the structure of biochar. The stability of immobilized laccase was better than that of free laccase in acid-base, heat, and storage. Among the three modified biochar immobilized laccases, JBC@LAC showed the best acid-base stability and thermal stability, and the relative enzyme activity changed the least when pH and temperature conditions changed. The storage stability of SBC@LAC is the best. After 30days of storage, the relative enzyme activity is still 83%. The removal rates of 2,4-DCP were 57, 99, and 63%, respectively, by SBC@LAC, JBC@LAC, and CBC@LAC. After five reuses, the removal rates of 2,4-DCP by SBC@LAC, JBC@LAC and CBC@LAC were 26, 42, and 27%, respectively. The intermediate products of 2,4-DCP degradation by immobilized laccase were p-phenol, p-benzoquinone and maleic acid.

Kinetics, comprehensive characteristics, and product analysis of peanut shell pyrolysis activated by a small amount of KCl

Simultaneous conversion of peanut shell (PS) by pyrolysis into energy and useful chemicals is essential for its maximum utilization. The pyrolysis kinetics of PS and KCl-activated PS (KCl-PS) were studied using isoconversional and integral master plots methods. The power law (P4) model was found to be the most appropriate pyrolysis mechanism, and KCl-PS had a lower average activation energy than PS. When 1.56 wt% KCl was used to activate PS pyrolysis, enhanced gas products and bio-oil with lower oxygen content were produced, and the BET surface area of biochar increased significantly from 1.02 m2/g to 503.45 m2/g. This may be because potassium reacts with oxygen-containing functional groups to form K2CO3, which promotes the cracking of labile aliphatic compounds (e.g., CO, CH, C-O, and OH groups). The exploratory factor analysis extracting three factors also showed that compared with PS, KCl-PS scored higher on the pyrolysis factor of labile aliphatic compounds and the factor including temperature and residual mass, but lower on the factor describing energy change.

Adsorption properties of active biochar: Overlooked role of the structure of biomass

Vascular plants account for more than 80% of all biomass on earth and are potential precursors of biochar. However, the changes of vascular bundle have received less attention during the preparation of biochar. In this study, loofah sponge (LS), tangerine pith (TP), and rhodiola rosea (RR), were selected to show the role of vascular bundle in biochar through the pretreatment of vascular bundle. The results showed that the active biochar prepared with vascular bundle protection had high adsorption capacity for methylene blue (LS: 953.53 mg/g, TP: 714.77 mg/g, RR: 583.49 mg/g). The Brunauer-Emmett-Teller method was used to measure the specific surface area (SSA) of active biochar. The SSA of LS active biochar prepared by vascular bundle protection was 2262.67 m2/g, and has high adsorption properties under different conditions. In conclusion, the protection of vascular bundle during biochar preparation is important to improve the utilization of biological resources and environmental adsorption.

Molecular Modelling and Characterization of Metal Incorporated Biochar from Industrial Wastes

Globally, manufacturing industries are generating a large volume of solid waste during their processes. These wastes, when spread through soil/water affect public health. This work focuses on the use of solid industrial waste from herbal medicine and TiO2 manufacturing industries to produce iron oxide incorporated biochar, which can be served as adsorbent and low cost catalyst for many reactions. Biochar was produced by the slow pyrolysis of waste collected from herbal manufacturing units using tubular furnace at 550°C at a heating rate of 5°C/min. The iron oxide waste collected from Kerala Minerals and Metals Limited, Kerala, India (KMML), was incorporated into the produced biochar by using planetary ball mill apparatus. Structural and elemental analysis of produced biochar and Fe2O3 incorporated biochar was conducted using XRD, SEM and SEM-EDS, BET surface area analysis, ICP-OES, and CHNS analysis. The H/C ratio of prepared biochar shows it has a rectangular layered structure of 50*50 aromatic cluster size. The changes in bonds and groups before and after metal incorporation were studied using FTIR spectroscopic analysis and temperature stability of prepared samples were analyzed using TGA. The molecular structure of produced biochar and changes in their bond length was studied and optimized employing Avogadro and Chemcraft software. The BET analysis shows the surface area of biochar become increased after the metallic incorporation. The same results were concluded from the molecular modelling data obtained from Chemcraft software. These results proved that the biochar surface area and pore volume can be increased by incorporation of iron oxide from industrial waste.

Targeted preparation of biochar for the application as composting additive: Influence mechanism of feedstock properties on biochar derived from traditional Chinese herb residue

The addition of biochar derived from traditional Chinese herb residue (TCHRs) into the composting process of herbal waste could help to achieve the carbon neutrality of the traditional Chinese medicine industry. However, because of the influence of the decoction process and the huge difference in the characteristics of herb residue from various parts, the feedstock properties greatly affect the physicochemical properties of biochar, which will influence the composting performance. In this study, the influence mechanism of feedstock properties on biochar derived from root, stem, and leaf parts of TCHRs was clarified. Results showed that the highest weight loss rates of root, stem and leaf residues after the decoction process increased to − 13.07 %/min, − 5.25 %/min and − 5.90 %/min due to the increasing volatile matter and decreasing ash content. In addition, the oxygen-containing functional groups were reduced, and better pore structures of biochar were developed after the decoction process, which would influence the microbial activity in the composting process. Moreover, the maximum specific surface area of root, stem and leaf residue biochar had reached 125.35 m2/g, 236.33 m2/g and 38.77 m2/g, respectively. The aromaticity of root biochar was up to 83.68 %, which mainly consisted of an aromatic C-C structure. And the aromaticity of leaf biochar was 86.74 %, which mainly consisted of aromatic C-O and C-H. Especially, the stem residue biochar bore a rich carbonyl structure, which helped reduce the risk of heavy metals in the composting process. Finally, it is supposed to choose different sorts of herbal biochar to be additive into various composting processes for the promotion of circular economy of the traditional Chinese medicine industry.

Unraveling biochar surface area on structure and heavy metal removal performances of carbothermal reduced nanoscale zero-valent iron

Carbothermal reduction using biochar (BC) is a green and effective method of synthesizing BC-supported nanoscale zero-valent iron (nanoFe0) composites. However, the effect of BC surface area on the structure, distribution, and performance such as the heavy metal uptake capacity of nanoFe0 particles remains unclear. Soybean stover-based BCs with different surface areas (1.7 − 1 472 m2/g) were prepared in this study. They have been used for in-situ synthesis BCs-supported nanoFe0 particles through carbothermal reduction of ferrous chloride. The BCs-supported nanoFe0 particles were found to be covered with graphene shells and dispersed onto BC surfaces, forming the BC-supported graphene-encapsulated nanoFe0 (BC-G@Fe0) composite. These graphene shells covering the nanoFe0 particles were formed because of gaseous carbon evolved from biomass carbonization reacting with iron oxides/iron salts. Increasing BC surface area decreased the average diameters of nanoFe0 particles, indicating a higher BC surface area alleviated the aggregation of nanoFe0 particles, which resulted in higher heavy metal uptake capacity. At the optimized condition, BC-G@Fe0 composite exhibited uptake capacities of 124.4, 121.8, 254.5, and 48.0 mg/g for Cu2+, Pb2+, Ag+, and As3+, respectively (pH 5, 25 °C). Moreover, the BC-G@Fe0 composite also demonstrated high stability for Cu2+ removal from the fixed-bed continuous flow, in which 1 g of BC-G@Fe0 can work for 120 h in a 4 mg/L Cu2+ flow continually and clean 28.6 L Cu2+ contaminated water. Furthermore, the BC-G@Fe0 composite can effectively immobilize the bioavailable As3+ from the contaminated soil, i.e., 5% (w) of BC-G@Fe0 composite addition can immobilize up to 92.2% bioavailable As3+ from the contaminated soil.

Engineering sulfuric acid-pretreated biochar supporting MnO2 for efficient toxic organic pollutants removal from aqueous solution in a wide pH range

Manganese dioxides (MnO2) and biochar materials are both desirable candidates for environmental remediation of toxic organic pollutants (TOPs) in water due to wide availability and environmental-friendly. In practical application, however, MnO2 suffers from low redox activity owing to deprotonation, while biochar is subject to limited removal capacity. Herein, a difunctional engineering sulfuric acid-pretreated biochar supporting MnO2 composite (MBC-A) was firstly synthesized and optimized to remove various TOPs from aqueous solution. Specifically, sulfuric acid not only served as an active agent to improve the specific surface area of biochar for improvement of adsorption capacity and more MnO2 loading, but also facilitated the introduction of sulfonic acid groups (-SO3H) as an internal proton reservoir to inhibit inactivation of MnO2 due to deprotonation in alkaline. Thanks to adsorption and oxidation, MBC-A showed excellent removal capacity (214.9 mg/g) and fast reaction kinetics (360 min) for tetracycline (TC), exceeding precursor and other materials reported in literature. Importantly, the effective operation pH range of MBC-A was broadened to 1–13 with the help of buffering capacity of –SO3H groups. The dominant driving force of adsorption were π-π interaction and hydrogen bond; while reactive oxidative species were mainly ascribed to singlet oxygen (1O2), hydroxyl radical (·OH) and reactive Mn3+. The possible reactive sites and pathway were investigated by combining experimental results with density functional theory (DFT) calculation. Further, the results of multiple cyclic runs, removal in real river water and toxicity assessment demonstrated well reusability, high environmental security, and excellent practical applicability of MBC-A.

The effect of biotransformation of sewage sludge- and willow-derived biochars by horseradish peroxidase on total and freely dissolved polycyclic aromatic hydrocarbon content

This study analyzed the effect of enzymatic aging (horseradish peroxidase) of biochars on their content of solvent extractable (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbons (PAHs). Physicochemical properties and phytotoxicity of pristine and aged biochars were also compared. The study used biochars obtained at 500 or 700 °C from sewage sludges (SSLs) or willow. Compared to SSL-derived biochars, willow-derived biochars were more susceptible to enzymatic oxidation. Aging increased the specific surface area and pore volume of most SSL-derived biochars. An opposite direction, however, was found in the willow-derived biochars. Low-temperature biochars, regardless of their feedstock, underwent physical changes, such as removal of labile ash components or degradation of aromatic structures. The enzyme caused an increase in the content of Ctot light PAHs in biochars (by 34–3402 %) and heavy PAHs (≥4 rings) in the low-temperature SSL-derived biochars (by 46–713 %). In turn, the content of Cfree PAHs decreased in aged SSL-derived biochars (by 32–100 %). In the willow-derived biochars the bioavailability of acenaphthene increased (by 337–669 %), while the immobilization degree of some PAHs was lower (25–70 %) compared to the SSL-derived biochars (32–83 %). Nevertheless, aging positively affected the ecotoxicological properties of all biochars by increasing their stimulation effects or removing their phytotoxic effects on both Lepidium sativum seed germination and root growth. Significant relationships between the changes in Cfree PAH content, pH and salinity of SSL-derived biochars and seed germination/root growth inhibition were found. The study demonstrates that the risk associated with application of SSL-derived biochars, regardless of the type of SSL and pyrolysis temperature, can be lower in terms of Cfree PAHs than in the case of willow-derived biochars. Regarding to Ctot PAHs, high-temperature SSL-derived biochars are safer than low-temperature ones. In the case of application of high-temperature SSL-derived biochars, these with moderate alkalinity and salinity will not bring risks for plants.

Sustainable eutectic mixture strategy of molten salts for preparing biochar with interconnected pore structure from algal residue and its performance in aqueous supercapacitor

A green ternary (NaCl/KCl/ZnCl2) mixed salt-assisted carbonization of spirulina residues was proposed to produce the nitrogen-doped biochar (NBC) with a hierarchical porous structure for the application of supercapacitors. Modifying the ratio of mixed salt to residues and the carbonization temperature allows it to control the specific surface area (SSA) of biochars, the type and content of functional groups, and the graphitization of the carbon skeleton. Here, the eco-friendly mixed salt functioned for a multifunctional purpose by acting as both a pore regulating agent and the reaction medium. The optimal 650–5 sample, produced by a reaction temperature of 650 °C and ratio of 5, exhibited remarkable specific capacitance of 215 F/g and 207 F/g at 0.2 A/g in 1 M H2SO4 and 6 M KOH electrolytes, respectively, and the composed symmetrical capacitors showed excellent cycling stability in the four aqueous electrolytes (plus 1 M Na2SO4 and 15 mol/kg LiTFSI), with capacitance retention rate all ≥90 % after 10,000 cycles. In the LiTFSI system, the energy density was 25.28 Wh/kg at 375.04 W/kg. Furthermore, experiments using recycled salt confirmed the sustainability of this approach.

Hydrothermal pretreatment of sugarcane bagasse pith for biogas production and digestate valorization to biochar

Sugarcane bagasse pith is generated as waste from bagasse-based paper industries which is still underutilized and mostly burnt as fuel in boilers. Therefore, an integrated pathway for the value-addition of the pith is explored. In the present study, hydrothermal pre-treatment of pith through response surface methodology and C/N was optimized for enhanced biogas production. At optimized conditions, a maximum biogas yield of 474.3 mL/gVS with ∼55% methane was attained with cellulose and reducing sugar of 59.2% and 3.68 g/L respectively. A severity factor of 3.8–4 was found suitable for cellulose enrichment, reducing sugar and biogas production, and at higher severity, a reduction in the above parameters was observed. Moreover, the digestate-based biochar delivered the highest biochar yield and surface area of 75.8 wt% and 254.47 m2/g respectively. This study is the first of its kind where the bagasse pith has been explored in a biorefinery approach to achieve circularity.

Effective Removal of Ammonium from Aqueous Solution by Ball-Milled Biochar Modified with NaOH

The objective of this study was to investigate the feasibility of using modified biochars to enhance removal of ammonium from aqueous solution. The pristine, NaOH-modified, ball-milled, and NaOH-modified ball-milled biochars were prepared from wheat straw at 500 °C. The surface morphology and characteristics of biochar were obviously changed after modification. The NaOH-modification elevated the pH value and ash content of biochar, and the ball-milling treatment promoted the formation of oxygen-containing functional groups. The specific surface area of biochar (20.9 m2/g) increased to 51.4 m2/g and 145.6 m2/g after NaOH-modification and ball-milling treatment, respectively. The modified biochars showed considerable ammonium sorption capacity in a wide pH range (3–7), and the optimal pH of ammonium sorption was around 6. Both NaOH-modification and ball-milling treatment improved ammonium sorption on the biochars. Ammonium sorption of the biochars could be well fitted by the Langmuir and pseudo-second-order model, and the NaOH-modified ball-milled biochar showed the highest ammonium sorption capacity of 8.93 mg g−1. The surface complexation with oxygen-containing functional groups and cation exchange were the dominant mechanisms of ammonium sorption on the biochars. These results indicate that NaOH-modified/ball-milled biochar has a good potential to be used for the ammonium removal from polluted water.

Effect of endogenetic dissolved organic matter on tetracycline adsorption by biochar.

The endogenetic biochar-derived dissolved organic matter (BDOM) might interact with pollutants in the environment. In this study, tetracycline (TC) was selected as the representative pollutant, and corn straw biochar (pyrolyzed at 300 °C) was used as the adsorbent. Through batch experiments and microscopic characterization, the releasing kinetics of BDOM and its effect on TC adsorption on biochar were investigated. The results showed that BDOM with weaker aromaticity and higher molecular weight was preferentially released. BDOM release led to the decrease of specific surface area (from 4.02 to 1.83 m2/g), mesopore number, and aromaticity of biochar (H/C increased from 0.80 to 0.91) and consequently weakened the pore filling of TC on biochar, hydrophobic interaction, and π-π EDA (electron donor receptor) interaction between biochar and TC. In addition, the released BDOM could form a complex with TC in solution to prevent TC adsorption on biochar. Overall, the change in the structural properties of biochar caused by BDOM release had a greater impact on the inhibition of TC adsorption than that of BDOM and TC complexation in this study. Through EEM-PRARFAC, BDOM contained about 63% humic acid-like fluorescent component and 37% tryptophan-like fluorescent component; the former (logKb values were 7.31 and 6.48, respectively) had a stronger binding strength with TC than the latter (logKb was 6.45). The findings of this study could provide some useful evidence for the removal of organic pollutants in soil and water environments and biochar application in pollution remediation.

Synthesis, characterization and thermo-kinetic analysis of sawdust biochar for adsorbent and combustion drives

Biochar is synthesized using two wood species as Dalbergia sissoo wood (DSW) and Mangifera indica wood (MIW), employing pyrolysis of sawdust on a lab-scale. Chemical analysis of these biochars is carried out using elemental analyzer, BET, FTIR, FE-SEM-EDX, and TGA-DTG-DTA analyses. Results showed that high surface area (87.12 and 88.04 m2/g), pore volume (0.0439 and 0.0443 cm3/g), and gross calorific value (28.19 and 28.00 MJ/kg) of DSW and MIW biochar indicate their suitability as sorbent and energy source. Thermogravimetric modeling, based on Coats-Redfern method, is applied on combustion data of biochar samples obtained at 10 and 20 °C/min. Activation energy of DSW- and MIW-biochar are estimated as 2.61–80.49 kJ/mol and 2.58–77.90 kJ/mol, respectively. Statistical analysis of results (R2 > 0.90) indicated the adequacy of proposed kinetic modeling in reproducing the experimental combustion behavior. The propitious outcome of this study account for favoring sawdust-biochar as a good adsorbent and combustion feedstock.

Role of cellulose and lignin on biochar characteristics and removal of diazinon from biochar with a controlled chemical composition

In this study, the effects of carbohydrate and lignin content in biomass on the production of biochar were investigated, and the adsorption behaviors of diazinon on the biochar obtained from delignified oak were evaluated. The lignin content in biomass can be controlled by delignification. Biomass lignin content decreased and cellulose content increased with increasing delignification time, thereby increasing the crystallinity index of delignified oak. Although the biochar yield of the delignified oak decreased, its specific surface area (354.68–444.36 m2/g) and total pore volume (0.162–0.202 cm3/g) were higher than those of the biochar obtained from raw material (193.22 m2/g and 0.093 cm3/g). In the delignified oak, the specific surface area and total pore volume of biochar increased with increasing delignification time. Mesopores and micropores were more developed in the biochar obtained from the delignified oak than in the raw material. The removal efficiency of diazinon by biochar increased with increasing delignification time. Based on the Langmuir and Freundlich isotherms, diazinon adsorption to biochar was suitable for the Langmuir model.

Effect of demineralization and ball milling treatments on the properties of Arundo donax and olive stone-derived biochar

The structural and physio-chemical properties of biochar are crucial to determining biochar’s quality and the adequate application. Specifically, the large porosity of biochar has been known as a favorable feature, especially for environmental remediation. In this regard, physical and chemical modifications have been used to improve biochar’s porosity which requires high-energy consumption and involves chemical agents. The objective of this study was to prepare biochar with developed porosity using mild treatments. Arundo donax and olive stone were demineralized by a water-washing method. Treated and non-treated biomasses were pyrolyzed, and part of the derived samples was subjected to wet ball milling. Samples were characterized with proximate, Fourier transform infrared, particle size, and physisorption analyses. The effect of demineralization depended on the biomass type, as ash reduction only influenced Arundo donax-derived biochar, which was attributed to the difference in initial ash content that was relatively low for olive stone. The carbonization yield decreased by 46% for the Arundo donax biomass after demineralization. Moreover, demineralization expanded the surface area and total pore volume of the Arundo donax biochar. The ball milling was effective in producing micro-sized biochar particles with a mean size ranging between 30 ± 2 µm and 42 ± 2 µm and between 13 ± 1 µm and 22 ± 2 µm for Arundo donax and olive stone without and with demineralization, respectively. Ball milling increased the surface area of non-demineralized Arundo donax by 47% and demineralized Arundo donax by 124%. Additionally, ball milling increased the surface area of non-demineralized olive stone by 65% and demineralized olive stone by 62%.Graphical abstract

Adsorption of lead ions by magnetic carbon: Comparison of magnetic carbon properties and modification methods

Magnetic biochar (MBC) is extensively used to remove contaminants from environmental media because of being easy to recover and separate. However, magnetic modification generally decreases the surface area of Biochar (BC), leading to an insignificant improvement in adsorption performance. In the present study, research was conducted on the changes in the physicochemical characteristics of the modified MBC in terms of elemental distribution, morphological characteristics, and surface functional groups based on magnetic carbon. Magnetic carbon was prepared using pine cone material and modified by four methods (ball milling, acid and oxidant modifications as well as metal impregnation). The role of contact time (0.25–8 h), initial Pb2+ concentration (5–200 mg/L), solution pH (2-7), and other process parameters in removing Pb2+ from the contaminated water was evaluated. The results showed that the maximum adsorption of Pb2+ by MBC reached up to 123.38 mg/g when time varied from 0.25 to 8 h. The proposed secondary kinetic and Langmuir isotherm models better proved the results of adsorption. The adsorption performance of ball milling modified MBC (BMBC) was evenly enhanced to varying degrees by several modification methods, especially ball milling with green and low-cost, a simple mechanical process to enhance the number and surface area of functional groups of MBC.

New insight into the adsorption of sulfadiazine on graphite-like biochars prepared at different pyrolytic temperatures

This study investigated the adsorption of sulfadiazine (SDZ) with four biochars prepared at 600, 700, 800 and 900 °C, and probed the potential rule connecting their chemical properties and adsorption capacities. Results showed that increasing the pyrolytic temperature, specific surface area, pore volume, aromaticity and aromatic cluster lateral size (La) of biochar markedly improved its adsorption capacity for SDZ. The maximum adsorption capacities (qm) of biochar600, biochar700, biochar800 and biochar900 for SDZ were 3.44, 17.87, 86.13 and 206.03 mg g−1, respectively. The pyrolytic temperature of 700 °C was the key temperature for the graphite-like biochar preparation, beyond which the La of biochar rapidly expanded. Compared with the pyrolytic temperature, specific surface area, pore volume and aromaticity of biochar, the La values of the four biochars exhibited a good positive linear correlation with their qm, indicating for the first time that La is an effective indicator to predict the adsorption capacity of graphite-like biochar. Density functional theory calculation further revealed that larger aromatic clusters could accommodate more SDZ molecules, and that the interaction among SDZ molecules in turn increased their binding energy with biochar. These findings in this study provide useful information for designing various efficient biochar adsorbents in the future.

Development of predictive model for biochar surface properties based on biomass attributes and pyrolysis conditions using rough set machine learning

Biochar can be used for environmental remediation, which includes carbon sequestration and soil quality improvement. Biochar is produced from the thermochemical conversion (i.e., pyrolysis) of biomass under inert conditions. However, there are no general rules regarding the relationship between biochar surface properties and biomass physiochemical properties as well as pyrolysis conditions. Machine learning (ML) algorithms can be used to investigate the relation between data sets and deliver useful decision output. In this work, rough set machine learning (RSML) was applied to generate a prediction model of biochar surface properties based on decisional attributes. The prediction model is a rule-based model that contains if-then rules to classify properties by fulfilling conditions. As a result, the specific surface area, pore volume, and pore diameter of biochar were found to be strongly influenced by pyrolysis conditions which includes temperature and retention time as well as biomass attributes including volatile matter, fixed carbon, and ash content. The results generated from RSML showed that the preferred range for pyrolysis temperature to produce biochar with desired surface properties is in between 425 °C and 625 °C, as well as retention time lower than 0.75 h.

Production, Characterization, and Activation of Biochars from a Mixture of Waste Insulation Electric Cables (WIEC) and Waste Lignocellulosic Biomass (WLB)

Waste insulation electrical cables (WIEC) currently do not have an added value, due to their physical–chemical characteristics. Carbonization is known to enhance feedstock properties, particularly fuel and material properties; as such, this article aimed to study the production and activation of biochars using WIEC and lignocellulosic biomass wastes as feedstock. Biochars were produced in a ceramic kiln with an average capacity of 15 kg at different temperatures, namely 300, 350 and 400 °C. After production, the biochars were further submitted to a washing process with water heated to 95 °C ± 5 °C and to an activation process with 2 N KOH. All biochars (after production, washing and activation) were characterized regarding an elemental analysis, thermogravimetric analysis, heating value, chlorine removal, ash content, apparent density and surface area. The main results showed that the increase in carbonization temperature from 300 to 400 °C caused the produced biochars to present a lower amount of oxygen and volatile matter, increased heating value, greater chlorine removal and increased ash content. Furthermore, the activation process increased the surface area of biochars as the production temperature increased. Overall, the carbonization of WIEC mixed with lignocellulosic wastes showed potential in enhancing these waste physical and chemical properties, with prospects to yield added-value products that activates biochar.