Biochar Production Research Articles

Novel utilization exploration for the dephosphorization waste of Ca–modified biochar: enhanced removal of heavy metal ions from water

Phosphorus-modified biochar has been proven to enhance the precipitation and complexation of heavy metal ions from wastewater. However, the current modification methods require large amounts of exogenous P and have high energy consumption. Hence, this study proposes and analyzes a strategy integrating biochar production, phosphorus wastewater treatment, dephosphorization waste recovery, and heavy metal removal. “BC-Ca-P” was derived from Ca-modified biochar after phosphorus wastewater treatment. The adsorption of Pb(II) by BC-Ca-P followed the Langmuir isotherm and pseudo–second–order kinetic models. The maximum adsorption capability of 361.20 mg·g−1 at pH 5.0 for 2 h was markedly greater than that of external phosphorous-modified biochar. The adsorption mechanisms were dominated by chemical precipitation and complexation. Furthermore, density functional theory calculations indicated that oxygen-containing functional groups (P-O and C-O) contributed the most to the efficient adsorption of Pb(II) onto BC-Ca-P. To explore its practical feasibility, the adsorption performance of BC-Ca-P recovered from an actual environment was evaluated. The continuous-flow adsorption behavior was investigated and well-fitted utilizing the Thomas and Yoon–Nelson models. There was a negligible P leakage risk of BC-Ca-P during heavy metal treatment. This study describes a novel and sustainable method to utilize dephosphorization waste for heavy metal removal.Graphical

Progressing environmental sustainability in hydroponic greenhouse systems: Embracing circular bioeconomy through compost and biochar pathways

The global population growth and awareness about the important role of vitamins in human health drive demand for fresh fruits and vegetables. In line with this need, greenhouse cultivation addresses year-round availability, but chemicals pose challenges. Hydroponic systems control pests, boost yields, and decrease chemicals while faced with significant waste generation. Waste generated by hydroponic systems holds potential for repurposing into value-added products, which aligns with the principles of the circular bioeconomy. However, before embracing widespread adoption, it is crucial to assess its environmental compatibility. This study employs a life cycle assessment approach to compare hydroponic tomato production in greenhouses under conventional and circular bioeconomy systems. The first scenario (Sc-1) encompasses hydroponic tomato production in a greenhouse system under a conventional system. The second scenario (Sc-2) involves the production of tomatoes, along with the conversion of residue of tomato production into compost. The third scenario (Sc-3) closely resembled Sc-2, while valorizing residue of tomato production into biochar. The outcomes indicate that per kg of tomato production under Sc-1 leads to a damage of 4.32 × 10−6 DALY to human health, 4.33E−06 species.yr to ecosystems, and 1.82 × 10−1 USD2013 to resources. The results of weighting of environmental damages also shows a total environmental damage of 75.36 mPt per kg of tomato production under Sc-1 which is mainly based on the production and consumption of natural gas. The findings demonstrate that Sc-2 and Sc-3 exhibit a diminished potential on damage to human health, ecosystems, and resource compared to Sc-1, respectively. Accordingly, in comparison to Sc-1, Sc-2 leads to an approximately 11% reduction in total weighted environmental impacts, while Sc-3 results in an approximately 4% reduction in total weighted environmental impacts. Based on these outcomes, integrating compost and biochar production into hydroponic tomato systems holds significant potential for environmental benefits. Accordingly, further research and development efforts should focus on optimizing the efficiency and scalability of composting and biochar production technologies to maximize their impact on sustainability in hydroponic tomato production.

Biochar Production from Plant Residues: A Sustainable Approach for Carbon Sequestration and Soil Fertility Improvement

This review article explores the sustainable practice of producing biochar from plant residues, effectively transforming green waste into a valuable resource commonly referred to as “green gold”. It discussed mainly on the pyrolysis process of biochar production, and the impact of different pyrolysis methods on the resulting biochar's properties, including surface area, porosity, and nutrient holding capacity. Further, the review analyzes the multifaceted benefits of biochar for soil health and plant growth. It highlights how biochar can improve soil structure, increase water retention, and enhance nutrient availability, leading to healthier and more productive agricultural lands. Additionally, the review explores biochar's potential in influencing the soil microbial community, potentially promoting beneficial organisms and suppressing harmful pathogens. It also explores biochar's role in mitigating climate change by capturing and storing atmospheric carbon, effectively reducing greenhouse gas emissions. However, a balanced perspective is maintained by acknowledging potential drawbacks associated with biochar use, such as the need for further research to optimize production methods and potential negative impacts on certain soil fauna. This review highlights biochar's promise as a sustainable, cost-effective solution for agriculture and environmental issues. Biochar adoption can lead to a greener future through carbon capture, soil health, and waste management.

Improving the Economic Feasibility of Small-Scale Biogas-Solid Oxide Fuel Cell Energy Systems through a Local Ugandan Biochar Production Method

A small-scale (up to 5 kWe) biogas-solid oxide fuel cell (SOFC) energy system is an envisioned system, which can be used to meet both electrical and thermal energy demand of off-grid settlements. SOFC systems are reported to be more efficient than alternatives like internal combustion engines (ICE). In addition to energy recovery, implementation of biogas-SOFC systems can enhance sanitation among these settlements. However, the capital investment costs and the operation and maintenance costs of a biogas-SOFC energy system are currently higher than the existing alternatives. From previous works, H2S removal by biochar was proposed as a potential local cost-effective alternative. This research demonstrates the techno-economic potential of locally produced biochars made from cow manure, jackfruit leaves, and jack fruit branches in rural Uganda for purifying the biogas prior to SOFC use. Results revealed that the use of biochar from cow manure and jack fruit leaves can reduce H2S to below the desired 1 ppm and substitute alternative biogas treatments like activated carbon. These experimental results were then translated to demonstrate how this biochar would improve the economic feasibility for the implementation of biogas-SOFC systems. It is likely that the operation and maintenance cost of a biogas-SOFC energy system can in the long run be reduced by over 80%. Also, the use of internal reforming as opposed to external reforming can greatly reduce the system capital cost by over 25% and hence further increase the chances of system economic feasibility. By applying the proposed cost reduction strategies coupled with subsidies such as tax reduction or exemption, the biogas-SOFC energy system could become economically competitive with the already existing technologies for off-grid electricity generation, like solar photovoltaic systems.

Integrating thermoelectric devices in pyrolysis reactors for biochar and electricity co-production

This study proposed an innovative approach to integrating thermoelectric devices with small-scale pyrolysis reactors by using Mizunara (Japanese oak) as the feedstock for biochar production. The primary objective of the study was to enhance the energy efficiency and carbon sequestration potential of the biochar production process by converting waste heat into electricity through thermoelectric devices. Comprehensive steady-state thermal balance analysis revealed that although covering the entire reactor surface with thermoelectric devices can result in excessive heat loss and reduced biochar yield, strategically limiting the installation area allows efficient power generation without considerably compromising biochar production. This balance between electricity generation and biochar yield is critical for optimizing the system’s efficiency. Historically, small-scale waste-heat power generation has been underdeveloped, but our studies have demonstrated that incorporating naturally cooled thermoelectric devices allows the generation of kilowatt-hour (kWh)-scale electricity from waste heat, which would otherwise be discarded. Furthermore, the analysis revealed that with optimized conditions, the CO2 equivalent values of the sequestered carbon can be substantially increased, providing a viable solution for long-term carbon storage. The results highlight the potential of this integrated approach to improve the energy efficiency of biochar production and provide a solution for waste-heat management. Moreover, we assessed the implementation effects by assigning reasonable values for the thermoelectric device performance and provide a robust framework for biomass utilization, waste-heat recovery, and CO2 sequestration.

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.

Assessing and enhancing sustainable rice straw management for environmental conservation in Yen Thanh District, Nghe An Province, Vietnam

This study assessed the current management of rice straw in Yen Thanh District, Nghe An Province, and propose solutions for sustainable agricultural development. A survey was conducted with 120 households in four communes to determine straw use and management practices. The findings revealed six common methods of using and managing rice straw in Yen Thanh District: open burning, burying, mushroom plantation, using it for husbandry feeding, selling, and giving it to others. These practices vary based on the crop season. Open burning is the most prevalent practice, accounting for 98.15% and 89.52% during the winter-spring and summer-autumn harvests, respectively. A crucial step in establishing a pollution control and management database is a comprehensive inventory of emissions. Consequently, authorities and environmental scientists are currently focusing on the emission inventory, particularly emissions resulting from open-burning rice straws. The estimated total amount of rice straw produced annually is 159,732 tons, with 151,384 tons being directly burned in the fields. This burning releases significant emissions, including 1,005.18 tons of PM2.5, 1,102.08 tons of PM10, 21.80 tons of SO2, 142,543.18 tons of CO2, and more, negatively impacting the environment, human health, and agriculture. Additionally, it was observed that most farmers are inclined to continue burning rice straw out of habit in the upcoming years. The study suggests promoting alternative straw management practices such as mushroom cultivation, biochar production, and organic fertilizer production to reduce burning and its associated negative consequences. This information would be invaluable for managers to effectively plan for the future management of rice straw

Investigation of biochars derived from waste lignocellulosic biomass and insulation electric cables: A comprehensive TGA and Macro-TGA analysis

This study investigates the thermochemical decomposition and gasification performance of biochars produced from blends of waste lignocellulosic biomass and waste insulation electrical cables at varying temperatures. Characterization tests revealed changes, particularly in ash content (27.5 %–34 %) and elemental composition, with nitrogen content increasing notably in biochar samples compared to the original feedstock. Van Krevelen diagrams demonstrated a reduction in O/C and H/C ratios with increasing production temperature, resembling fossil fuels more closely. The thermogravimetric and the derived thermogravimetric profiles illustrated distinct degradation stages influenced by heating rates and production temperature. Macro-TGA tests provided insights into biomass residue behavior under gasification conditions, indicating higher reaction rates at elevated temperatures. Syngas analysis highlighted the impact of temperature and equivalence ratio on syngas composition, with higher temperatures favoring hydrogen-rich gas production. The observed trends in cold gas efficiency (42.61 %–50.40 %) and carbon conversion efficiency (45.83 %–50.40 %) underscore the significance of temperature control in maximizing gasification performance. Biochars produced at higher temperatures demonstrated superior gasification performance, suggesting potential for optimizing biochar production processes to enhance energy recovery and waste valorization.

Valorization of coffee agro-industrial residue for biochar production: Use as adsorbent for methylene blue removal

This research explores using thermally modified residual coffee grounds as a bioadsorbent for removing methylene blue (MB) from aqueous solutions. The study investigates the impact of pH on adsorption capacity, emphasizing its significant influence. Kinetic studies reveal that the pseudo-first-order (PFO) model accurately describes the MB removal process, with correlation coefficients (R²) close to 1 for all samples. The Freundlich model provided the best fit for residual coffee grounds, while the Langmuir model was most suitable for biochar 1. The BiDR model provides the best fit with high R² values, indicating efficient removal for biochar 2 and biochar 3. Notably, the research shows that MB adsorption is effective without requiring pH adjustments, thereby reducing environmental impacts. The maximum adsorption capacities were 40.85, 20.35, 19.52 and 41.98 mg.g−1 using residual coffee grounds, biochar 1, biochar 2 and biochar 3, respectively. Overall, this study demonstrates the practicality of using thermally activated coffee grounds as an efficient adsorbent for removing textile dyes from effluents and highlights the potential of alternative uses for coffee grounds and biochar residues in environmental applications.

Exploring Biomass Conversion Technologies: From Raw Materials to Valuable Products

The global demand for eco-friendly energy has propelled biomass into the spotlight. This report delves into biomass conversion technologies, including biochemical and thermochemical processes, with a focus on hydrothermal conversion. It highlights challenges related to cost-effectiveness and commercial viability. Thermochemical conversion processes, such as pyrolysis and combustion, unlock energy from organic matter. Hydrothermal processing's three approaches and their efficiency are discussed, particularly in biofuels, chemicals, and biochar production. The review analyzes hydrothermal gasification, emphasizing its efficiency and minimal processing time. Carbon and hydrogen gasification efficiencies are crucial in determining gas yields in supercritical conditions. Yield distribution and the influence of feedstock nature and composition on product yield are examined. In conclusion, this report offers insights into biomass conversion technologies and their sustainability for energy and chemical needs.

Evaluation of waste composition for biochar production as a sustainable waste management approach

Background: To meet human life needs, fuel energy is obtained from fossil sources, such as coal, found in the Earth's crust. However, non-renewable energy sources in the Earth's crust will eventually run out. One alternative fuel is the production of biobriquettes from various types of waste. Methods: Using a literature review method, this study aims to determine which waste is most suitable for use in the production of biobriquettes. The samples taken are journals sourced from Google Scholar ranging from 2017 to 2022 that align with the discussion topic. Findings: Among various raw materials, the best waste for biobriquette production is found to be a mixture of dacron waste and corn cob, with a moisture content of 3.45% and a carbon value of 7986.45 cal/g. Conclusion: The results of the above study indicate that the production of biobriquettes from dakron waste and corn cobs is the best option because it yields the highest calorific value and the lowest moisture content, in accordance with SNI 01/6235/2000. Novelty/Originality of this article: This study presents a novel approach by identifying a specific combination of dacron waste and corn cob for biobriquette production, showcasing its superior calorific value and low moisture content, thus contributing to sustainable energy solutions and waste management practices.

Techno-economic assessment of swine manure biochar production in large-scale piggeries in China

Biochar production using swine manure (SM) from large-scale piggeries is increasingly needed. However, little is known about the economic feasibility for SM biochar production. Herein, SM biochar production was simulated via Aspen Plus, and techno-economic model was applied to calculate the net present value (NPV), internal rate of return (IRR), and discounted payback period (DPP) for SM biochar production with a processing capacity of 8000 tons SM per year. Results suggest that this project is susceptible to biochar selling price and operation cost. When the biochar price is > 116 USD/ton, the NPV is positive. When the biochar selling price is increased from 154 to 193 USD/ton, the IRR is increased from 11 % to 41 %. The DPP analyses show that the investment payback period for this project is 4.6 years. Moreover, compared to conventional SM treatment routes, valorization of SM into biochar in large-scale piggery in China has a shorter investment period. Finally, this study suggests that swine manure biochar production in large-scale piggeries in China is profitable, deserving investment.

Analysis of the Impact of Biomass/Water Ratio, Particle Size, Stirring, and Catalysts on the Production of Chemical Platforms and Biochar in the Hydrothermal Valorization of Coffee Cherry Waste

In Colombia alone, 12.6 million bags of green coffee are produced, but at the same time, 784,000 tons of waste biomass are dumped in open fields, of which only 5% is recovered or used, and 10 million tonnes of coffee emit 28.6 million tonnes of CO2 eq annually. This presents a worrying dilemma, and the need to develop a technology to transform the waste into usable products is increasing. As a response to this, the valorization of coffee waste was explored through the production of biochar and platform chemicals by implementing a set of hydrothermal experiments with different biomass/water ratios (1:5, 1:10, 1:20, 1:40), particle sizes (0.5, 1, 2, 5 mm), stirring rates (5000 and 8000 rpm), and catalysts (H2SO4, NaHCO3 and CH3COOH) at 180, 220, and 260 °C in a batch reactor with autogenous pressure. Notably, the smaller B:W ratios of 1:20 and 1:40, as well as smaller particle sizes of 0.5 and 1 mm, yielded higher amounts of platform chemicals, while stirring showed minimal influence. CH3COOH significantly enhanced the process compared to other catalysts. The biochar was characterized as anthracite, and this obtaining of coal-like materials from biomass itself represents a remarkable feat. Said anthracite presented little to no variation in physical parameters, while catalysts induced functionalization. By optimizing factors like B:W ratio, particle size, and catalyst application, valuable insights have been gained into enhancing the yield of platform chemicals and quality of biochar from coffee waste. The findings not only contribute to sustainable waste management practices but also highlight the importance of exploring innovative solutions for utilizing agricultural by-products effectively.

Production, properties, and applications of pharmaceutical sludge-derived biochar

Pharmaceutical sludge is considered hazardous waste in many countries, and pyrolysis treatment of pharmaceutical sludge is a newly popular field. This study comprehensively examines the effects of various pretreatment pHs on the structure and practical application efficiencies of pharmaceutical sludge-derived biochar. Results revealed that the acidic biochar was not only richer in functional groups, but also had more visible structural defects, making it more favorable for application as a catalyst. Furthermore, the biochar pretreated at pH 3.0 produced the greatest amount of persistent free radicals and hydroxyl radicals. Additionally, the biochar pretreated at pH 3.0 demonstrated the most effective tetracycline removal, with a removal efficiency of 57.84 mg/g-biochar. Compared to the control test, the addition of biochar could achieve considerable bactericidal effect. This paper demonstrates scientific and guiding significance to the pyrolysis process and applications of biochar derived from pharmaceutical sludge.

The biochar derived from Spirulina platensis for the adsorption of Pb and Zn and enhancing the soil physicochemical properties

Microalgae can be collected in large quantities and hold significant potential for environmental remediation, offering a cost-effective solution. This study explores the use of Spirulina platensis (SP) as feedstock for biochar production. SP contains abundant nitrogen-rich components, such as proteins, which can serve as nitrogen sources. We prepared SP-derived biochar through pyrolysis for the adsorption of Pb and Zn from aqueous solutions and used it as an amending agent to remediate heavy metal-contaminated agricultural soil. Pyrolysis of proteins in SP introduces nitrogen-functional groups, resulting in nitrogen-doped biochar. We investigated the surface chemical behavior of thermally treated SP using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Surface analysis revealed the presence of pyridine-N and pyrrole-N from protein pyrolysis products. The study also demonstrated that these functional groups affect interactions with heavy metals. Batch experiments examined the effects of pH and initial concentration on the adsorption of Pb and Zn using SP400 and SP600. Both types of biochar showed satisfactory performance in adsorbing Pb and Zn. The effect of SP400 and SP600 on the removal of Pb and Zn through the physicochemical properties and surface functional groups was investigated. Analysis of SP400 and SP600 highlighted that electrostatic interactions, cation exchange, complexation, and mineral precipitation contributed to Pb and Zn adsorption. The study concludes that SP-derived biochar, particularly SP600, is effective for immobilizing Pb and Zn in contaminated agricultural soil, with SP600 showing superior performance.

Pea Pod Valorization: Exploring the Influence of Biomass/Water Ratio, Particle Size, Stirring, and Catalysts on Chemical Platforms and Biochar Production

This study delves into the valorization of pea pod waste using hydrothermal processes, focusing on optimizing key parameters such as temperature, biomass-to-water ratio, particle size, and catalyst influence. Noteworthy findings include the significant impact of temperature variations on product yields, with 180 °C favoring sugars, HMF, and furfural, while 220 °C and 260 °C lead to distinct platform chemical productions. The utilization of a 1:20 biomass-to-water ratio consistently enhances yields by 10%, underscoring its importance in promoting efficient hydrolysis without excessive product degradation. Furthermore, the investigation into particle size reveals that smaller dimensions, particularly 1 mm particles, improved heat and mass transfer, reduced diffusion barriers, and enhanced digestibility, ultimately boosting overall efficiency in platform chemical production. Moreover, the study sheds light on the role of catalysts in the hydrothermal processes, showcasing the differential impact of acid and basic catalysts on product yields. Acid catalysts demonstrate a notable increase of up to 135.5% in the production of platform chemicals, emphasizing their crucial role in enhancing reaction efficiency. The complex relationship between agitation, temperature, and product formation is elucidated, with experiments revealing varying outcomes based on the presence or absence of agitation at different temperatures. These findings provide valuable insights into optimizing pea pod waste valorization, offering a pathway towards sustainable and efficient conversion of agricultural residues into valuable platform chemicals.

Analyzing the Impact of Annealed Steel Sludge Doses on the Physicochemical Properties of Biochar Obtained from Waste Date Palm Frond

Large quantities of date palm frond waste generated from the pruning process are accumulated or burned in burn barrels, harming the environment and having very little economic value. However, because of the lack of data revealing the characteristic magnetic properties of biochar derived from date palm fronds, further research on low-cost and sustainable strategies could offer a new composite material and serve to extend the way for novel applications. In this study, we prepared biochar derived from palm fronds via pyrolysis under a limited-oxygen atmosphere at a lower temperature of 300 °C for 2 h. We introduced a facile strategy for the production of magnetic biochar with various doses of annealed steel sludge material via ball milling. Various amounts of annealed steel sludge material (5%, 15%, and 25% w) were added to date palm frond biochar, and the obtained product was fabricated by ball milling. The physicochemical characteristics of the magnetic biochar composite were subsequently analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and UV-vis spectroscopy. Our findings showed that the ball milling method is a successful step for producing date palm fronds with magnetic biochar material possessing rough and packed pores, as shown by SEM. XRD patterns assumed the existence of magnetic phases of iron oxide (magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3) at different generated peaks. FTIR outputs exhibited the abundant presence of various oxygen-containing functional groups (- COOH and -OH) on the surface of magnetic biochar material, which help to create chemically reactive sites to adsorb potential surrounding species. The UV spectra showed a noticeable enhancement of the optical properties of the magnetic biochar with an increase in the sludge dose for light absorption in the visible region from wavelengths of 400 – 700 nm . This result signifies the synthetic optimization and potential application of magnetic biochar materials for composites that could be employed in targeted uses including soil amendment, water remediation and energy applications.

Enhancing environmental and economic benefits of constructed wetlands through plant recovery: A life cycle perspective

Plant recovery plays a vital role in reclaiming bioresources from constructed wetland wastewater treatment systems. A comprehensive understanding of the environmental impacts and economic benefits associated with various wetland plant resourcing methods is critical for advancing both plant resource recovery and the application of wetlands in wastewater treatment. In this study, life cycle assessment was employed to evaluate the environmental impacts and costs of seven wetland plant recovery methods. In addition, the potential benefits of extending plant resource recovery within system boundaries were explored to enhance the overall advantages of constructed wetlands for wastewater treatment. The use of wetland plants for biofertilizer production had the lowest environmental impact (−8.52E-03), whereas the use of wetland plants for biochar production was the most cost-effective approach (−0.80€/kg). The introduction of a plant resource recovery component could significantly reduce the environmental impacts of constructed wetland wastewater treatment systems. The environmental impacts and costs of constructed wetland wastewater treatment systems that incorporate plant resource recovery into the system boundary are better than activated sludge methods and highly efficient algal ponds, except for the global warming potential (GWP). The use of plants for biofertilizer production could cut the environmental impacts of constructed wetland wastewater treatment systems by up to 85 % and the costs by 65 %, making it the most suitable method of plant use. Additionally, prioritizing the reduction of greenhouse gas emissions from constructed wetlands should be a primary optimization goal. The findings of this study provide valuable support for the implementation of wetland plant resourcing in constructed wetland wastewater treatment systems.

Adsorbents Produced from Olive Mill Waste and Modified to Perform Phenolic Compound Removal

Olive mill waste (olive pomace, OP, and olive stone, OS) was used in this work to produce adsorbents for the removal of five phenolic acids typically found in olive mill wastewater. OP and OS were subjected to different treatments (combined or not) that were chemically modified (NaOH) or physically modified by two different methods, incipient wetness impregnation (IWI) and hydrothermal deposition (HD), and even biochar production obtaining a total of 16 materials. The materials were characterized by different analytical techniques such as N2 absorption, scanning electron microscopy, infrared spectroscopy, and pH zero-potential charge. The mixture of five phenolic acids was used to evaluate in batch conditions the adsorption capacity of the prepared materials. OS chemically modified with IWI (OSM-IWI) and OS biochar with HD (BOS-HD) presented better adsorption capacity at 157.1 and 163.6 mg/g of phenolic acids, respectively, from a total of 200 mg/g. For some materials, the surface area cannot be correlated with adsorption capacity, unlike pHzpc, where high values fit better adsorption rates. The infrared spectroscopy profile indicates the presence of O-H and N-H functional groups and, the last one, red-shifted in the IWI preparation compared to the HD one. In addition to this, the prepared material from olive mill waste can be suitably used for the mixture of phenolic compounds.

Effects of lignin syringyl to guaiacyl ratio on cottonwood biochar adsorbent properties and performance

Lignin syringyl to guaiacyl ratio (S/G) has long been suspected to have measurable impacts on biochar formation, but these effects are challenging to observe in biochars formed from whole biomass. When the model bioenergy feedstock Populus trichocarpa (cottonwood), with predictable lignin macromolecular structure tied to genetic variation, is used as feedstock for biochar production, these effects become visible. In this work, two P. trichocarpa variants having lignin S/G of 1.67 and 3.88 were ground and pyrolyzed at 700 °C. Water-demineralization of feedstock was used to simultaneously evaluate any synergistic influences of S/G and naturally-occurring potassium on biochar physicochemical properties and performance. The strongest effects of lignin S/G were observed on specific surface area (SBET) and oxygen-content, with S/G of 1.67 improving SBET by 11% and S/G of 3.88 increasing total oxygen content in demineralized biochars. Functional performance was evaluated by breakthrough testing in 1% NH3. Breakthrough times for biochars were nearly double that of a highly microporous activated carbon reference material, and biochar with S/G of 3.88 had 10% longer breakthrough time than its lower S/G corollary. Results support a combination of pore structure and oxygen-functionalities in controlling ammonia breakthrough for biochar.