Biomass Resources Research Articles

Acid Resistance Engineering of Endoglucanase for the Degradation of Wine Lees.

Wine lees is a low value biomass resource rich in cellulose, with great potential for producing organic fertilizers and chemicals. However, the high acidity of wine lees limits the catalytic efficiency of the conversion tool endoglucanase. Here, we expressed endoglucanase tCel5A from Trichoderma reesei in Pichia pastoris, and the combination of promoter AOX1 and signal peptide SUC2 resulted in a highly active expression of 4632.81 U/mg. Subsequently, the catalytic center design and surface charge modification strategy resulted in mutants T88H/W255H and S45D/T55D/T59D exhibiting catalytic activity twice and three times higher than WT at pH 3.0, respectively. Finally, when the solid-liquid ratio was 1:15 (w/v), the degradation rate of wine lees was nearly double that of WT. The degradation products contained a variety of industrial and pharmaceutical raw components, including the antioxidant and anticonvulsant isopiperolein B. This study accelerates the green and sustainable management of wine lees.

Products Distribution and Reaction Kinetics from Co-Pyrolysis of Pinewood and Polypropylene under Non-Catalytic and Catalytic Reaction Conditions

Abstract Co-pyrolysis technology offers vital pathways for efficient utilization of plastics and biomass resources to help reduce the environmental problems and energy resources issues. The pyrolysis characteristics of pinewood and polypropylene (PP) mixtures were analyzed using TGA. The results showed a decrease in first peak of the mixture with increase in PP in the mixture, while the second peak increased with an increase in PP in the mixture. The addition of a catalyst decreased the DTG peak heights. The reduction in the first peak with different catalysts was in the order: CaO/ZSM-5 >CaO >ZSM-5, while for the second peak showed: CaO >CaO/ZSM-5 >ZSM-5. The activation energy, calculated by Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman models, revealed that ZSM-5 reduced the activation energy, whereas CaO/ZSM-5 increased the activation energy, as compared to no catalyst case. Increase of co-pyrolysis temperature reduced the yield of aldehydes, ketones, acids and esters, but increased the yield of hydrocarbons. The addition of CaO reduced the yield of ketones, phenols, esters, and acids, while it increased the yield of alcohols. The addition of ZSM-5 also decreased the yield of ketones, phenols, acids and hydrocarbons, but increased the yield of furans and alcohols. The addition of CaO/ZSM-5 specifically reduced the yield of aldehydes and alcohols. The results show the important role of the specific catalysts examined on the resulting products distribution for the same reaction condition.

Self-sacrificing and self-supporting biomass carbon anode–assisted water electrolysis for low-cost hydrogen production

Electrooxidation of renewable and CO2-neutral biomass for low-cost hydrogen production is a promising and green technology. Various biomass platform molecules (BPMs) oxidation assisted hydrogen production technologies have obtained noticeable progress. However, BPMs anodic oxidation is highly dependent on electrocatalysts, and the oxidation mechanism is ambiguous. Meanwhile, the complexity and insolubility of natural biomass severely constrain the efficient utilization of biomass resources. Here, we develop a self-sacrificing and self-supporting carbon anode (SSCA) using waste corncobs. The combined results from multiple characterizations reveal that the structure-property-activity relationship of SSCA in carbon oxidation reaction (COR). Theoretical calculations demonstrate that carbon atoms with a high spin density play a pivotal role in reducing the adsorption energy of the reactive oxygen intermediate (*OH) during the transition from OH- to *OH, thereby promoting COR. Additionally, the HER||COR system allows driving a current density of 400 [Formula: see text] at 1.24 V at 80 °C, with a hydrogen production electric consumption of 2.96 kWh Nm-3 (H2). The strategy provides a ground-breaking perspective on the large-scale utilization of biomass and low-energy water electrolysis for hydrogen production.

Sustainable production of BioAIE materials from biomass

The research of aggregation‐induced emission (AIE) materials has aroused extensive interests during the past 20 years. Until recently, biomass‐inspired AIE (BioAIE) materials have become highly attractive owing to the advantages of natural structural diversity, renewability, biocompatibility, and biodegradability of the biomass. In this concept, we focus on the sustainable production of BioAIE materials from biomass resources (biomacromolecules and small natural products) through extraction, chemical conversion, and physical conversion. Chemical conversion is especially stated, including catalytic conversion, Schiff base reaction, “in water” reaction, and other chemical modifications. The luminescence mechanism of AIE behaviors along with their structure‐property relationships is emphasized, and the applications are addressed as well. An outlook is provided to highlight the challenges and opportunities associated with the future development trend in this field.

Valorization of White Lupin Straw Through Mild Dilute Acid Hydrothermal Treatment: A Sustainable Route for Monosaccharide and 5-Hydroxymethylfurfural Production

This study investigates the potential use of white lupine straw (WLS), an underutilized agricultural by-product, as a raw material to produce valuable biochemicals such as monosaccharides and 5-hydroxymethylfurfural (5-HMF) through hydrothermal pretreatment. The aim was to optimize mild reaction conditions to maximize the recovery of these products while minimizing degradation. The hydrothermal treatment of WLS in subcritical water with trace amounts of sulfuric acid was performed, followed by a two-step approach to evaluate the yields of hemicellulose and 5-HMF. The highest monosaccharide yield (163 g/kg) was achieved at temperatures between 174 and 181 °C and a holding time of 7–14 min, while the 5-HMF production was 139.9 g/kg at 199–203 °C and after 0.5–4.5 min. These results suggest that optimal 5-HMF production also increases the remaining solid residue. This study highlights the feasibility of WLS as a sustainable, low-cost biomass resource. It highlights the balance between temperature and time to maximize valuable product yields. The results contribute to advancing biorefinery processes by demonstrating that WLS can be effectively converted into bioethanol precursors and industrial chemicals, supporting circular bioeconomy principles and providing an environmentally friendly alternative to burning crop residues.

Investigation of biomass gasification and fluidization behaviour for pilot double tapered bubbling fluidized bed reactor.

The present investigation discusses syngas production through gasification from six different bamboo biomass species available in India's northeast region (Mizoram). The thermochemical conversion of biomass to syngas is accomplished in a novel double-tapered reactor. The pre-processing stage of biomasses includes various shredding, drying, and sieving methods. In the processing stage, the biomass (20g) is fed to the reactor regularly. The heating element in the interior of the reactor supplies the heat required (600-1000°C) for the combustion and gasification of biomass samples. The influence of various particle sizes on bed voidage, pressure drop, bed height, suspension density, gas yield, heat transfer, and carbon conversion efficiency is studied. The tapered reactor enhanced the bed hydrodynamics. It is observed that the H2 and CO2 composition increases with the temperature (> 900°C), whereas the CO composition is reduced as a result of the shift reaction. However, the CH4 yield is enhanced at a temperature (< 800°C) but lessened at higher temperatures due to a reduction in moisture content. The carbon conversion efficiency (CCE) and the dry gas yield (YG) values obtained are better for the particle size of 1.18mm than the other particle sizes. The energy from biomass resources is promising regarding sustainability, availability, and efficacy. The current approach discusses the syngas generation from bamboo biomass through gasification under varied temperature ranges (600-1000°C), equivalence ratio (0.2), particle sizes (380µm, 600µm, and 1.18mm), superficial velocity (0-2m/s) in a pilot 5kg/h DTBFBR of height 1.2m and maximum inner diameter of 16.5cm.

Deep Eutectic Solvent and Molten Salt-Assisted Construction of Wheat Straw-Derived N/O Co-Doped Porous Carbon for Flexible Zinc-Air Batteries.

As a common biomass resource, wheat straw is gradually being derived as carbon materials for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). Herein, the wheat straw-derived carbon was prepared by ball milling and pyrolysis using deep eutectic solvent (DES) as the medium, which avoided the cumbersome procedures. The hydrogen bond of DES was utilized to reconstructed into a hydrogen bond network structure between DES and lignin/cellulose/hemicellulose of wheat straw. The hydrogen bond network structure was converted into N/O co-doped porous carbon (N/O-WSPC) with abundant N/O co-doped sites after high-temperature pyrolysis. Meanwhile, KHCO3 was employed to further generate hierarchical pore structures and increase the specific surface area of the N/O-WSPC. The N/O co-doped sites provided intrinsic ORR activity, while the porous structure facilitates the mass transfer effect. Therefore, the N/O-WSPC exhibited a half-wave potential of 0.87 V (vs. RHE) and a limiting current density of 5.98 mA cm-2 for ORR. The N/O-WSPC-based flexible ZAB displayed an energy density of 652.23 Wh kg-1 and a charging-discharging cycle duration for over 19 h. The DES-assisted strategy facilitates the sustainable and efficient application of wheat straw-derived carbon materials in energy storage and conversion devices.

Research on Hybrid Heating System in Cold Oilfield Regions

Efficient and clean treatment of wastewater and energy recovery and utilization are important links to realize low-carbon development of oilfields. Therefore, this paper innovatively proposes a multi-energy complementary co-production heating system which fully and efficiently utilizes solar energy resources, oilfield waste heat resources, and biomass resources. At the same time, a typical dormitory building in the oil region was selected as the research object, the system equipment selection was calculated according to the relevant design specifications. On this basis, the simulation system model is established, and the evaluation index and operation control strategy suitable for the system are proposed. The energy utilization rate of the system and the economic, energy-saving, and environmental benefits of the system are simulated. The results show that, under the simulated conditions of two typical days and a heating season, the main heat load of the system is borne by the sewage source heat pump, the energy efficiency is relatively low in the cold period, and the energy-saving characteristics are not obvious. With the increase in heating temperature and anaerobic reactor volume, the energy consumption of the system also increases, and the energy efficiency ratio of each subsystem and the comprehensive energy efficiency ratio of the system gradually decrease. In addition, although the initial investment in cogeneration heating systems is high, the operating costs and environmental benefits are huge. Under the condition of maintaining 35 °C, the anaerobic reactor in the system can reduce carbon emissions by 12.15 t per year, reduce sulfur dioxide emissions by 98.4 kg, reduce dust emissions by 49.2 kg, and treat up to 2700 t of sewage per year, which has broad application prospects.

Sustainable passive radiation cooling transparent film for mobile phone protective screens

Passive daytime radiative cooling (PDRC) is a promising approach to address energy, environmental, and safety issues caused by global warming, with high emissivity in a transparent atmospheric window and high reflectivity in the solar spectrum. However, most demonstrations of PDRC rely mainly on complex and expensive spectral selective nanophotonic structures, requiring specialized photonic structures that are both expensive and difficult to obtain. The superiorities of low-cost, abundant resources, renewability, and high value-added biomass resources prompt Gleditsia sinensis polysaccharides (GSP) to be used in thermal emission materials to explore further the characteristics of regulating object temperature within a specific range without any external energy consumption. The three-layer thermal emission film (PDMS3PG3/t4) obtained by the scalable scraping method has high transparency, hydrophobicity (114.2°), and super flexibility. The spectral variations of non-selective PDMS3PG3/t4 (1.0 wt% GSP, 800 μm thickness) in the 3–5 μm and 8–13 μm waveband ranges were discussed in detail, and high emissivities of 69.1 % and 92.2 % were obtained, respectively. PDMS3PG3/t4 was appointed a mobile phone screen film and experimented with a 4.9 °C average temperature difference below ambient temperature, materializing prime PDRC and desiring to broaden the passive cooling technology and reduce the global energy burden.

Membrane Separations in Biomass Processing.

The development of integrated biorefineries and the greater utilization of biomass resources to reduce dependence on fossil fuel-derived products require research emphasis not just on conversion strategies but also on improving separations associated with biorefining. A significant roadblock towards developing biorefineries is the lack of effective separation techniques evidenced by the lack of literature in this area. Additionally, high conversion yields may only be realized if effective separations generate feedstock of sufficient purity - this makes research into biomass conversion strategies all the more critical. In this review, the challenges associated with biomass separations are discussed, followed by an overview of the most appropriate separation strategies for processing biomass. One of the unit operations most appealing for biorefining, membrane separations (MS), is then considered along with a review of the recent literature utilizing this technique in biomass processing.

A platform chemical from soybean hulls: Unveiling the bioactive effects of levoglucosenone derivatives

Soybean is one of the most extensively cultivated crops globally, and the soybean oil industry produces a significant amount of hulls annually. Utilizing this by-product to generate levoglucosenone through acid-catalyzed pyrolysis represents an environmentally friendly strategy to maximize the use of this crop and increase the value of the residue.This study explored the pyrolysis of soybean hulls to obtain the target enone and its application in the generation of new antifungal compounds. Halogenated derivatives were synthesized in a simple and straightforward manner and evaluated for antifungal activity against several Candida and Cryptococcus strains. Mechanistic studies investigated their interactions with ergosterol, impact on fungal cell wall synthesis, and inhibition of virulence factors. Biofilm formation assays were also conducted. Our results showed that the chloro derivative demonstrated the highest antifungal activity, exhibiting a remarkable minimum inhibitory concentration (MIC) and efficacy against both susceptible and resistant strains. It was also showed that the mode of action does not involve ergosterol bonding nor inhibition of cell wall synthesis. This study provides valuable insights into utilizing agricultural waste for developing bioactive compounds with pharmaceutical applications, contributing to the sustainable utilization of biomass resources in pharmaceutical research and development.

Furfural production from xylan using a Pueraria Residues carbon-based solid-acid catalyst.

The conversion of biomass into high value-added platform compounds is an important method of biomass utilization. The conversion of hemicellulose represented by xylan into furfural can not only reduce the consumption of fossil fuels, but also promotes the development and utilization of non-edible biomass resources. In this study, a bifunctional solid-acid catalyst prepared from agricultural and forestry waste Pueraria (P. eduli) Residues was used to convert xylan into furfural in a biphasic system. In this study, P. eduli Residues was used as raw material to prepare a P. eduli Residues-based carbon solid-acid catalyst (PR/C-SO3H-Fe) by one-step sulfonation carbonization and impregnation. The catalyst catalyzes the conversion of xylan to furfural in a biphasic system (2-methyltetrahydrofuran/water). The physicochemical properties of the catalysts were characterized by X-ray powder diffraction, scanning electron microscopy, differential thermogravimetric analysis, Brunauer-Emmett-Teller surface area, Fourier transform infrared spectroscopy and ammonia temperature-programmed desorption. Subsequently, the experimental conditions were studied and optimized, such as metal species, iron ion concentration, reaction time and temperature, volume ratio of organic phase to water phase and ratio of substrate to catalyst. The results showed that under conditions of 160 °C, 50 mg catalyst, 100 mg xylan and 7 mL reaction solvent, the yield of furfural could reach 78.94% after 3 h of reaction. This study provides an effective research method for the conversion of xylan into furfural, and provides a reference for the catalytic conversion and utilization of hemicellulose in agricultural and forestry biomass. It also provides a feasible method for the resource utilization of agricultural and forestry waste. © 2024 Society of Chemical Industry.

A Review of the Technological Aspects and Process Optimization of Bioethanol Production From Corn Stover Biomass: Pretreatment Process, Hydrolysis, Fermentation, Purification Process, and Future Perspective

ABSTRACTBioethanol, a sustainable energy solution derived from renewable biomass, has gained prominence, with corn stover emerging as a substantial biomass resource in Indonesia. Corn stover, a corn residue, is one of the top three agricultural wastes worldwide and is abundantly available. However, a significant portion of corn stover is burned in fields rather than utilized for bioethanol production, whereas it has potential as a bioethanol feedstock. As the world strives to realize sustainable and environmentally friendly energy security, bioethanol production from corn stover can be one of the solutions to be developed. Nonetheless, the current immaturity of bioethanol production technology is one of the causes of large‐scale production failure. The present paper comprehensively reviews the technological aspects and process optimization of bioethanol production using corn stover as a feedstock comprising pretreatment, hydrolysis, fermentation, and bioethanol purification processes. According to our critical review, ammonia fiber expansion (AFEX) pretreatment is the most effective conventional pretreatment, with glucose yield up to 90%. Moreover, ultrasound appears to be the most viable option for nonconventional pretreatment of corn stover for producing bioethanol. However, combining ultrasound pretreatment and dilute aqueous ammonia produced 80.6% sugar output. Furthermore, enzymatic hydrolysis emerges as the most effective saccharification, yielding up to 81.39%. Moreover, the fermentation process of corn stover with the saccharification and co‐fermentation (SScF) method and the process optimization with response surface methodology (RSM) could produce bioethanol with a concentration of up to 59.8 g/L and 92.07% ethanol yield, respectively. This review also reveals that pervaporation for the purification process is the best choice for producing bioethanol with high purity up to &gt; 99%. In addition, this method could reduce the energy used by 6.6% lower, 24.2% lower carbon footprint, and have the lowest total capital and production costs compared to conventional molecular sieves and extractive distillation. We believe this review article can provide a reference for selecting the best bioethanol production process from corn stover for further research.

Advancements in synergistic fermentation of probiotics and enzymes for non‐grain feed raw materials

AbstractTo address the escalating challenge of food scarcity and the associated conflicts between human and animal consumption, it is imperative to seek alternative resources that can substitute for traditional feed. Non‐grain feed (NGF) raw materials represent a category of biomass resources that are distinct from grains in their composition. These materials are characterized by their high nutritional content, cost‐effectiveness, ample availability, and consistent supply, which contribute to their significant economic potential. Nonetheless, the extensive application of NGF is currently hindered by several limitations, including a high concentration of antinutritional factors, suboptimal palatability, and an offensive odor, among other shortcomings. The synergistic fermentation of probiotics and enzymes (SFPE) is an innovative approach that integrates the use of a diverse array of enzymes during the feed fermentation process, as well as various strains of probiotics throughout the feed digestion process. This method aims to enhance the nutritional value of the feed, diminish the presence of antinutritional factors, and improve the overall palatability, thereby facilitating the optimal utilization of NGF. This strategy holds the promise of not only replacing conventional feed options but also mitigating the pressing issue of grain scarcity. This paper delves into the practical applications of NGF and presents an overview of the latest research advancements in SFPE fermentation techniques, which can provide cutting‐edge and valuable reference for researchers who devote themselves to research in this field in the future.

Enhancing the selective catalytic oxidation of lignocellulosic biomass to formic acid using hydrogen peroxide and a reusable MgAl hydrotalcite-derived as a catalyst in a green solvent

Biofuels or liquid fuels derived from natural matter, are one of the most intriguing yet divisive alternatives for petroleum-based fuels. The most common approach to produce biofuels is to transform plant sugars and other carbohydrates into oxygen-deficient chemicals. A growing relevance has been devoted in the direct synthesis of platform molecules from biomass resources, using one-pot or cascade techniques via adequate catalytic system tuning and improvement of the reaction conditions which have merged as a beneficial strategy from an economic and ecological standpoint. In a similar vein, the major objective of this contribution was to investigate and enhance the conditions for a selective oxidation of lignocellulosic biomass-derived cellulose to yield formic acid (FA), the latter is one of the most coveted liquid hydrogen carriers and among the key compounds used in the pharmaceutical, cosmetic, and leather industries. Both oxidizing aqueous hydrogen peroxide and calcined heterogeneous hydrotalcite catalyst have been employed at an atmospheric pressure for this purpose. The effect of reaction time, temperature, amount of catalyst and oxidant on the product's yield and selectivity have been investigated. The oxidation of a plant-derived cellulosic fiber at 70 °C using an H2O2 excess (7 mmol) provided an impressive result with a high yield and TON of 61.0 %, 12.30 respectively, the latter was confirmed to be relatively close to the one from the oxidation of pure cellulose. Furthermore, the reusability of the catalyst has also been studied which was demonstrated to result in the same yields for one reuse and 3 recycles.

Deciphering the Impact of Lignin on Anaerobic Digestion: Focus on Inhibition Mechanisms and Methods for Alleviating Inhibition.

China has abundant lignocellulosic biomass resources. These resources are converted into biogas by anaerobic digestion (AD), which not only realizes the comprehensive utilization of waste resources but also obtains abundant biomass energy. However, the low biodegradability of lignocellulosic biomass caused by the complex structure has seriously hindered its utilization by enzymes and microorganisms, resulting in low biogas production and limited development of biogas engineering. The purpose of this work is to analyze the mechanism of lignin inhibiting AD and summarize the main methods for alleviating inhibition. Based on this, this review examines the factors influencing lignin's inhibition of methane production during AD from two key perspectives: (1) discussing lignin's biodegradability challenges, with a focus on its structure, functional groups, and the impact of lignin content in lignocellulosic biomass on its methanogenic potential, and (2) analyzing lignin's impact on each stage of AD. In addition, we provide insights into future research directions in this field.

Pea Pod–Derived Biochar–Zeolitic Imidazolate Framework Composite for the Photocatalytic Degradation of Two Organic Dyes Crystal Violet and Victoria Blue

ABSTRACTThe rapid increase of water pollution globally is a vital environmental concern that requires the immediate attention of researchers to find new innovative ways to remove unwanted environmental pollutants from our water sources. With the advances in the field of sustainable engineering, there is a high demand for the effective utilization of biomass resources for the removal of aqueous environmental contaminants. Biochar is carbon carbon‐enriched substance obtained by biomass pyrolysis; it is inexpensive and has received wide attention in the field of wastewater treatment. Herein, we describe the synthesis of pea pod (PO) biochar‐reinforced zeolitic imidazolate framework (ZIF‐8) nanocomposite (PO@ZIF‐8) through the in situ precipitation of ZIF‐8 onto the biochar surface. The crystal growth, morphology, chemical composition, and optical characteristics of fabricated PO@ZIF‐8 nanocomposite were scrutinized through PXRD, SEM, TEM, UV‐DRS, PL, and XPS analysis. The dodecahedral‐shaped PO@ZIF‐8 particles have an average size between 140 and 160 nm. The biochar‐reinforced ZIF‐8 nanocomposite showed significantly higher photocatalytic activity than the pure ZIF‐8 for the degradation of two commonly found organic dyes crystal violet (CV) and Victoria Blue (VB) in the presence of direct sunlight irradiation. The PO@ZIF‐8 nanocomposite showed the highest degradation efficiency of ~87% and ~80% within 50 min of irradiation time at a catalyst dosage of 20 mg for 30 ppm CV and VB dye solutions at pH 8. First‐order kinetics were obeyed during the photodegradation with 0.041 and 0.030 min−1 as the constant of degradation for the removal of CV and VB. The radical scavenger experiment and the photoluminescence analysis confirm the active participation of ·OH radical in the degradation of both dyes. LC–MS and TOC analysis was also performed to determine the degradation products and for evaluation of the degradation progress. Moreover, the synthesized PO@ZIF‐8 composite also exhibit good stability till the fourth cycle with high degradation efficiency thus making it a good choice of catalyst in the field of environmental decontamination.

Efficient synthesis of 2,5‐furandicarboxylic acid from corncob biomass using Ru/C and sulfonated carbon catalysts in a one‐pot system

AbstractThis study proposes a novel one‐pot method to produce 2,5‐furandicarboxylic acid (FDCA), which effectively simplifies the preparation process of FDCA by directly utilizing the biomass raw material corncob and its derived carbon‐based catalysts. In this work, we first prepared two different carbon‐based catalysts from corncobs: a ruthenium‐supported catalyst (Ru/C) and a sulfonated carbon catalyst. After detailed characterization and performance testing, these two catalysts were used to catalyze the pretreated corncob mixture to produce FDCA. Under optimized conditions, even using 0.12 g of Ru/C catalyst at a microwave power of 200 W, the yield of FDCA can reach 27 mol%. In comparison, the FDCA yield of the sulfonated carbon catalyst under the same conditions was 19 mol%. This work not only demonstrates the possibility of efficient production of FDCA by utilizing biomass resources and a simplified chemical conversion process, but also highlights the importance of selecting appropriate catalysts and controlling reaction conditions in improving yields. Through this method, we can promote the development of biomass conversion technology in a more efficient and environmentally friendly direction, providing technical support for the commercial production of bio‐based chemicals.

Remediation of Cd-As-Ni co-contaminated soil by extracellular polymeric substances from Bacillus subtilis: Dynamic improvements of soil properties and ecotoxicity

As the primary reservoir of heavy metals in nature, soil is highly susceptible to significant co-contamination with Cd-As-Ni. In current study, extracellular polymeric substances (EPS) from Bacillus subtilis were utilized as a novel improver to simultaneously enhance soil property and restrain ecotoxicity in Cd-As-Ni co-contaminated soil. Our findings revealed that EPS effectively bound and immobilized free Cd, As, and Ni in soil and decreased the 49.73 % of soil available Cd, 79.16 % of As and 77.87 % of Ni contents by increasing soil pH, soil organic matter and cation exchange capacity. The EPS was also found to inhibit the Cd-As-Ni induced ecotoxicity in Caenorhabditis elegans by increasing the activities of antioxidant enzymes including superoxide dismutase, glutathione, and catalase. The remediation of EPS showed progressive improvement over time, and maintained a lasting effect after achieving peak efficiency. Our results might provide a new perspective on the potential of EPS in remediation of soil heavy metal pollution and the development and utilization of microbial biomass resources in a wider range.

Performance and Mechanism of Porous Carbons Derived from Biomass as Adsorbent for Removal of Cr(VI)

To solve the problem of heavy metal hexavalent chromium (Cr(VI)) pollution in water bodies, this study was carried out to prepare nitrogen-doped porous carbon by using bamboo shoots as the raw material and KHCO3 as the activator, which has a good ability to remove Cr(VI) from water bodies. The prepared N-doped carbon materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and scanning electron microscopy (SEM). The results showed that the prepared carbon material had hierarchical pore structures and abundant functional groups, which is conducive to the adsorption of Cr(VI). The effects of various factors on the adsorption performance of Cr(VI), such as the carbon materials prepared under different conditions, the pH of the initial solution, the concentration of the initial solution, and the contact time between the carbon and Cr(VI), were explored. The results showed that the bamboo shoot-based nitrogen-doped carbon materials, especially BSNC-800 (prepared at 800 °C with a mass ratio of KHCO3 to bamboo shoot of 4:1), performed well in removing Cr(VI) from a water solution. The maximum adsorption of Cr(VI) by BSNC-800 under equilibrium conditions was 385.8 mg g−1 (conditions: at the pH of 2 with the initial concentration of 400 mg L−1). The adsorption kinetics and isotherms were analyzed, and the adsorption mechanism was discussed. It can be found that the adsorption of Cr(VI) by BSNC-800 fits better with the Langmuir isotherm model and the pseudo-second-order kinetic model. The adsorption mechanism between the Cr(VI)-containing solution and BSNC-800 was controlled by membrane diffusion and chemisorption. The results broaden the ways of utilizing biomass resources as precursors of carbon materials, which is significant and helpful for applying biomass carbon materials as adsorbents for wastewater treatment.