Hemicellulosic Hydrolysate Research Articles

Comparative study of single stage and two-stage pretreatments on corn stover: A kinetic assessment

The effects of two-stage pretreatment consisting of tepid water (first stage) and FeCl3 (second stage) pretreatments on hemicellulose hydrolysis were investigated. A kinetic comparison between the single stage (FeCl3-only pretreatment) and the two-stage pretreatment was evaluated. Compared with single stage pretreatment, the two-stage pretreatment decreased the activation energy Ea of hemicellulose hydrolysis by 38.3% and decreased the optimal reaction time by 34.8%. Besides, the xylose content increased by 14.9% and the catalyst dosage decreased by 31.9% in the two-stage pretreatment. This study provided an efficient pretreatment process for hemicellulose hydrolysis.

Microwave-Assisted Hydrolysis of Hemicellulose over Sulfonated Catalysts

Sulfonated catalysts based on zirconia (SO3H-ZrO2), silica (SO3H-SBA-15) and zeolite (SO3H-ZSM-5) were studied in the catalytic hydrolysis reaction of hemicellulose in a microwave reactor. The prepared catalysts were characterized by various techniques (XRD, N2 physisorption at 77 K, SEM, TEM and NH3-TPD). The obtained results reveal that despite the differences in their structural and textural properties, the ZrO2, Al-SBA-15 and H-ZSM-5 supports show similar conversions. Doping supports with sulfonate species created hydrogen bonds between SO3H groups and increased the amount of weak acid sites, which enhanced the hydrolysis of hemicellulose. SO3H- ZSM-5 showed the highest catalytic activity followed by SO3H-SBA-15 while SO3H-ZrO2 exhibited a poor conversion. Furthermore, the catalytic hydrolysis of the hemicellulose leads to several interesting products, such as formic acid, acetic acid, lactic acid and xylan. The correlation between the catalytic performances and the acidic properties of the different samples indicates that the best catalytic performances were obtained with the least acidic solids and especially when the density of strong acid sites decreases.

Integral Analysis of Liquid-Hot-Water Pretreatment of Wheat Straw: Evaluation of the Production of Sugars, Degradation Products, and Lignin

Developing sustainable biorefineries is an urgent matter to support the transition to a sustainable society. Lignocellulosic biomass (LCB) is a crucial renewable feedstock for this purpose, and its complete valorization is essential for the sustainability of biorefineries. However, it is improbable that a single pretreatment will extract both sugars and lignin from LCB. Therefore, a combination of pretreatments must be applied. Liquid-hot-water (LHW) is highlighted as a pretreatment for hemicellulose hydrolysis, conventionally analyzed only in terms of sugars and degradation products. However, lignin is also hydrolyzed in the process. The objective of this work was to evaluate LHW at different conditions for sugars, degradation products, and lignin. We performed LHW at 160, 180, and 200 °C for 30, 60, and 90 min using wheat straw and characterized the extract for sugars, degradation products (furfural, hydroxymethylfurfural, and acetic acid), and lignin. Three conditions allowed reaching similar total sugar concentrations (~12 g/L): 160 °C for 90 min, 180 °C for 30 min, and 180 °C for 60 min. Among these, LHW performed at 160 °C for 90 min allowed the lowest concentration of degradation products (0.2, 0.01, and 1.4 g/L for furfural, hydroxymethylfurfural, and acetic acid, respectively) and lignin hydrolysis (2.2 g/L). These values indicate the potential use of the obtained sugars as a fermentation substrate while leaving the lignin in the solid phase for a following stage focused on its extraction and valorization.

Modelling Based Analysis and Optimization of Simultaneous Saccharification and Fermentation for the Production of Lignocellulosic-Based Xylitol

Simultaneous saccharification and fermentation (SSF) configuration offers efficient use of the reactor. In this configuration, both hydrolysis and fermentation processes are conducted simultaneously in a single bioreactor, and the overall processes may be accelerated. However, problems may arise if both processes have different optimum conditions, and therefore process optimization is required. This paper presents a mathematical model over SSF strategy implementation for producing xylitol from the hemicellulose component of lignocellulosic materials. The model comprises the hydrolysis of hemicellulose and the fermentation of hydrolysate into xylitol. The model was simulated for various process temperatures, prior hydrolysis time, and inoculum concentration. Simulation of the developed kinetics model shows that the optimum SSF temperature is 36 °C, whereas conducting prior hydrolysis at its optimum hydrolysis temperature will further shorten the processing time and increase the xylitol productivity. On the other hand, increasing the inoculum size will shorten the processing time further. For an initial xylan concentration of 100 g/L, the best condition is obtained by performing 21-hour prior hydrolysis at 60 °C, followed by SSF at 36 °C by adding 2.0 g/L inoculum, giving 46.27 g/L xylitol within 77 hours of total processing time. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Characteristics of adapted and non-adapted Candida tropicalis InaCC Y799 during fermentation of detoxified and undetoxified hemicellulosic hydrolysate from sugarcane trash for xylitol production

Characteristics of adapted and non-adapted Candida tropicalis InaCC Y799 during fermentation of detoxified and undetoxified hemicellulosic hydrolysate from sugarcane trash for xylitol production

Enhanced Enzymatic Hydrolysis of Cellulose From Substrate and Indole-3-Acetic Acid Content-During the Fruiting Body Differentiation Stage by Sodium Acetate Addition.

Volvariella volvacea, with high commercial, nutritional and medicinal value, is widely cultivated in tropical and subtropical regions. The effects of supplementation on mushroom yield has been studied. We showed that the optimal application of sodium acetate (NaAc) was spray application of a 0.08% concentration during the substrate mixing stage which could increase yields by up to 89.16% and enhance the enzymatic hydrolysis of cellulose and hemicellulose from the substrate. For most enzymes tested maximum activity occurred during the fruiting body growth and development stage, which led to degradation of the substrate, increasing the available nutrients for mycelial propagation and fruiting body growth and development. Meanwhile, NaAc also significantly increased the indole-3-acetic acid (IAA) content in the early fruiting body development stage of V. volvacea, It was observed that IAA promotes not only plant primordium differentiation; but also the primordium differentiation of edible fungi. Furthermore, treatments with three acetate salts had an increase of yield by 30.22% on average. The mechanisms by which NaAc application may improve the yield of V. volvacea are discussed.

The Kinetics Studies on Hydrolysis of Hemicellulose.

The kinetics studies is of great importance for the understanding of the mechanism of hemicellulose pyrolysis and expanding the applications of hemicellulose. In the past years, rapid progress has been paid on the kinetics studies of hemicellulose hydrolysis. In this article, we first introduced the hydrolysis of hemicelluloses via various strategies such as autohydrolysis, dilute acid hydrolysis, catalytic hydrolysis, and enzymatic hydrolysis. Then, the history of kinetic models during hemicellulose hydrolysis was summarized. Special attention was paid to the oligosaccharides as intermediates or substrates, acid as catalyst, and thermogravimetric as analyzer method during the hemicellulose hydrolysis. Furthermore, the problems and suggestions of kinetic models during hemicellulose hydrolysis was provided. It expected that this article will favor the understanding of the mechanism of hemicellulose pyrolysis.

Co-production of bioethanol and xylosaccharides from steam-exploded eucalyptus sawdust using high solid loads in enzymatic hydrolysis: Effect of alkaline impregnation

In this work, Eucalyptus grandis sawdust was investigated as raw matter for the co-production of xylosaccharides (XS) and bioethanol by steam explosion pretreatment with and without a previous NaOH impregnation stage. The acetyl groups were completely removed in the NaOH impregnation step, which inhibited the autohydrolysis during the steam explosion pretreatment. The best results, in terms of XS recovery and glucan content in the pretreated substrate, were obtained when E. grandis was subjected to steam explosion at 200 °C for 10 min without alkaline impregnation. 76 kg of XS per ton of sawdust were obtained from the hemicellulosic hydrolysate and were mostly xylose or short xylo-oligosaccharides (XOS) (83% and 17%, respectively). High hydrolysis efficiencies were obtained using high solids loading (27%) with the steam pretreated material. High ethanol concentrations (75.6 g/L) and yields (259 L per ton of dry raw sawdust) were obtained by simultaneous saccharification and fermentation (SSF), representing a suitable strategy for ethanol production from eucalyptus sawdust.

Induction of resistance mechanisms in Rhodotorula toruloides for growth in sugarcane hydrolysate with high inhibitor content.

The oleaginous yeast Rhodotorula toruloides is a potential lipid producer for biodiesel production. However, this yeast shows growth inhibition due to harmful compounds when cultivated in hemicellulose hydrolysate. Here, we present a comparative analysis of colony selection and heterologous adaptive laboratory enhancement (ALE) strategies for obtaining robust strains. We implemented these ALE strategies for R. toruloides in a culture medium containing sugarcane hemicellulose hydrolysate. Our comparison study showed that the strain obtained with heterogeneous ALE strategy (Rth) reached a µmax of 55% higher than the parental strain. It also exhibited higher biomass production (6.51g/l) and lipid content (60%). ALE with colony selection strategy (Rtc) had a fitness gain in terms of shortening of the lag phase (9h) when compared to Rth and parental strain (11.67, 12.33h, respectively). When cultivated in Eucalyptus urograndis hemicellulose hydrolysate, the Rth strain achieved a high lipid content, 64%. Kinetics studies showed a strong effect of acetic acid as a repressor of xylose consumption during R. toruloides cultivation.Key points• Distinct adaptive laboratory strategies resulted in strains with different physiologies.• Heterologous adaptive laboratory enhancement provided the best results (fitness gain of 55% in µmax).• The Rth strain achieved a lipid content of 64.3% during cultivation in eucalyptus hemicellulose hydrolysate.

Effects of acid treatment on the physicochemical and functional properties of wheat bran insoluble dietary fiber

AbstractBackground and ObjectivesWheat bran is a by‐product of the wheat milling industry but most are used as animal fodder or discarded. To extend the applications of wheat bran, the structural, physicochemical, and functional properties of sulfuric acid‐modified wheat bran insoluble fibers (WBIDF) produced using 1%, 2%, 4%, and 8% H2SO4 and 1.5% potassium hydroxide were investigated.FindingsDue to cell wall disintegration, 1.0% and 2.0% H2SO4 treatments increased the concentration of soluble dietary fiber. Scanning electron microscopy indicated that acid treatment disrupted WBIDF structure, removed starch granules from the surface, and significantly reduced starch content. Higher H2SO4 concentrations increased WBIDF crystallinity due to hydrolysis of hemicellulose and amorphous cellulose. Acid treatment below 2% not only enhanced the water holding, water swelling, oil binding, and cation exchange capacities of WBIDF, but also increased cholesterol, sodium cholate, and glucose adsorption capacities and α‐amylase inhibition activity.ConclusionsAcid‐modified WBIDF has potential as a functional food ingredient.Significance and noveltyAcid treatment can be used to disrupt the microstructure of wheat bran to improve its functional properties. These findings can be utilized to improve the technological functionality of wheat bran as a high fiber ingredient for food applications.

Effects of microplastics on soil carbon dioxide emissions and the microbial functional genes involved in organic carbon decomposition in agricultural soil

The accumulation of microplastics (MPs) in agricultural fields can not only disguise soil organic carbon (SOC) storage but also affect the production of carbon dioxide (CO2) by microbial decomposition. However, little is known about the impact of this emerging pollutant on soil CO2 emissions and the functional genes related to SOC degradation. In the present study, a short-term (30-day) microcosm experiment was performed to investigate the effects of virgin and aged low-density polyethylene (LDPE) MPs on soil CO2 emissions. We also measured functional gene abundances related to starch (sga), hemicellulose (abfA, manB and xylA), cellulose (cex) and lignin (lig and mnp) degradation through a high-throughput quantitative-PCR-based chip. Compared with the soils without MPs, low doses (0.01% and 0.1%) of both virgin and aged MPs had negligible effects on SOC decomposition, whereas a high dose (1.0%) of these two MPs significantly (p < 0.05) accelerated the production of CO2 in soils by 15–17%, showing a dose-dependent effect. The presence of MPs did not significantly affect soil dissolved organic carbon or microbial biomass carbon. A higher metabolic quotient at 1.0% MP concentration indicated that the microbes were stressed and needed more substrates and energy during their metabolic process, which could likely explain the increase in CO2 emission induced by this dose of MPs. Exposure to virgin MPs significantly reduced the functional genes related to hemicellulose (abfA and manB) degradation, whereas increasing the aged MPs concentrations significantly decreased the abundances of functional genes encoding starch (sga), hemicellulose (abfA, manB and xylA), and cellulose (cex) hydrolysis. Overall, we conclude that the low dose (<0.1%) of MPs in the soils has a negligible effect on the production of CO2, but this factor should be considered in evaluating the global C budget in future research as this contaminant reaches a certain threshold (1.0%).

Simplified configuration for conversion of sugars from sugarcane bagasse into ethanol

The biochemical production of second generation ethanol involves pretreatment, enzymatic hydrolysis and fermentation, which can be carried out using different configurations. In the present study, sugarcane bagasse was pretreated with dilute H2SO4, saccharified (enzymes), and fermented (Scheffersomyces stipitis). Two configurations, fermentation of hemicellulosic hydrolysate (FHH) separated from separate hydrolysis and fermentation of pretreated solids (SHF), in fractions obtained after filtration of the slurry, and integrated hydrolysis of pretreated solids separated from co-fermentation of cellulosic and hemicellulosic hydrolysates (IHSCF), in whole slurry, were evaluated for ethanol production. Washed or non-washed pretreated solids, and neutralized (NaOH) or detoxified (laccase) hemicellulosic hydrolysates, were evaluated in the first configuration. Neutralized (NaOH), pre-supplemented (nutrients), or detoxified (laccase) slurries in non-hybrid and hybrid systems, in the second configuration. Detoxification improved conversions in both configurations. Maximum efficiency in SHF + FHH configuration was 28.4% in 168 h, while, in IHSCF configuration, 38.9% was obtained in 96 h.

Isolation and Screening of Microorganisms for the Effective Pretreatment of Lignocellulosic Agricultural Wastes.

Lignocellulosic waste is the most abundant biorenewable biomass on earth, and its hydrolysis releases highly valued reducing sugars. However, the presence of lignin in the biopolymeric structure makes it highly resistant to solubilization thereby hindering the hydrolysis of cellulose and hemicellulose. Microorganisms are known for their potential complex enzymes that play a dominant role in lignocellulose conversion. Therefore, the current study was designed to isolate and screen potential microorganisms for their selective delignification ability for the pretreatment of lignocellulosic biomass. An extensive isolation and screening procedure yielded 36 desired isolates (22 bacteria, 7 basidiomycete fungi, and 7 filamentous fungi). Submerged cultivation of these desired microorganisms revealed 4 bacteria and 10 fungi with potent lignocellulolytic enzyme activities. The potent isolates were identified as Pleurotus, Trichoderma, Talaromyces, Bacillus, and Chryseobacterium spp. confirmed by morphological and molecular identification. The efficiency of these strains was determined through enzyme activities, and the degraded substrates were analyzed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). Among all isolated microbes, Pleurotus spp. were found to have high laccase activity. The cellulose-decomposing and selective delignification strains were subjected to solid-state fermentation (SSF). SSF of field waste corn stalks as a single-carbon source provides Pleurotus spp. better condition for the secretion of ligninolytic enzymes. These isolated ligninolytic enzymes producing microorganisms may be used for the effective pretreatment of lignocellulosic agricultural wastes for the production of high value-added natural products by fermentation.

Short-term Adaptation Strategy Improved Xylitol Production by Candida guilliermondii on Sugarcane Bagasse Hemicellulosic Hydrolysate

In this work, we proposed a short-term adaptation strategy to improve xylitol production on sugarcane bagasse hemicellulosic hydrolysate through the maximization of Candida guilliermondii FTI 20037 tolerance to inhibitors. Hemicellulosic hydrolysate obtained by diluted acid hydrolysis (1.0% (wv−1) H2SO4, 1:10 solid/liquid ratio, 121 °C, 10 min) was concentrated up to fivefold to obtain hydrolysates with different concentration factors. Yeast was cultivated in each hydrolysate for 24-h and consecutively transferred to the subsequent more concentrated hydrolysate to obtain different adaptation degrees. Adapted cells were used as inoculum in fermentations with the same hydrolysate in which they were adapted. The performance of adapted and non-adapted yeast was compared to validate the adaptation strategy employed. The beneficial effects of adaptation were more pronounced in the hydrolysates with higher inhibitor concentration (twofold concentrated and non-treated, H2N; and fivefold concentrated and treated, H5). It improved xylose assimilation and xylitol production as well as xylitol yield and xylitol volumetric productivity in both hydrolysates. A 62.5% increase in productivity (0.24 to 0.39 gL−1 h−1) and a 15.7% increase in yield (0.51 to 0.59 gg−1) were observed for H5 hydrolysate, while for H2N hydrolysate these increases were 54.5 and 29.6%, respectively. Yeast adaptation also improved arabinose consumption and reduced glycerol production. The reduction in glycerol production indicates a greater tolerance of adapted cells to the inhibitors present in hydrolysates. Short-term adaptation proved to be an efficient strategy to improve yeast tolerance as well as its fermentative performance on sugarcane bagasse hemicellulosic hydrolysate.

Energy Densification of Biomass-Derived Furfurals to Furanic Biofuels by Catalytic Hydrogenation and Hydrodeoxygenation Reactions

The concomitant hydrolysis and dehydration of biomass-derived cellulose and hemicellulose to furfural (FUR) and 5-(hydroxymethyl)furfural (HMF) under acid catalysis allows a dramatic reduction in the oxygen content of the parent sugar molecules with a 100% carbon economy. However, most applications of FUR or HMF necessitate synthetic modifications. Catalytic hydrogenation and hydrogenolysis have been recognized as efficient strategies for the selective deoxygenation and energy densification of biomass-derived furfurals generating water as the sole byproduct. Efficient and eco-friendly catalysts have been developed for the selective hydrogenation of furfurals affording renewable furanic compounds such as 2-methylfuran, 2,5-dimethylfuran and 2-methyltetrahydrofuran with potential applications as biofuel, solvent and chemical feedstock. Hydrogen gas or hydrogen donor molecules, required for the above processes, can also be renewably obtained from biomass using catalytic processes, enabling a circular economy. In this review, the recent developments in the energy densification of furfurals to furanic compounds of commercial significance are elaborated, emphasizing the role of catalyst and the reaction parameters employed. Critical discussion on sourcing hydrogen gas required for the processes, using hydrogen donor solvents, catalyst design and the potential markets of furanic intermediates have been made. Critical evaluations of the accomplishments and challenges in this field are also provided.

Comparison of Spathaspora passalidarum and recombinant Saccharomyces cerevisiae for integration of first- and second-generation ethanol production.

First-generation ethanol (E1G) is based on the fermentation of sugars released from saccharine or starch sources, while second-generation ethanol (E2G) is focused on the fermentation of sugars released from lignocellulosic feedstocks. During the fractionation process to release sugars from hemicelluloses (mainly xylose), some inhibitor compounds are released hindering fermentation. Thus, the biggest challenge of using hemicellulosic hydrolysate is selecting strains and processes able to efficiently ferment xylose and tolerate inhibitors. With the aim of diluting inhibitors, sugarcane molasses (80% of sucrose content) can be mixed to hemicellulosic hydrolysate in an integrated E1G-E2G process. Cofermentations of xylose and sucrose were evaluated for the native xylose consumer Spathaspora passalidarum and a recombinant Saccharomyces cerevisiae strain. The industrial S. cerevisiae strain CAT-1 was modified to overexpress the XYL1, XYL2 and XKS1 genes and a mutant ([4-59Δ]HXT1) version of the low-affinity HXT1 permease, generating strain MP-C5H1. Although S. passalidarum showed better results for xylose fermentation, this yeast showed intracellular sucrose hydrolysis and low sucrose consumption in microaerobic conditions. Recombinant S. cerevisiae showed the best performance for cofermentation, and a batch strategy at high cell density in bioreactor achieved unprecedented results of ethanol yield, titer and volumetric productivity in E1G-E2G production process.

Integrated bioprocess for bio-ethanol production from watermelon rind biomass: Ultrasound-assisted deep eutectic solvent pretreatment, enzymatic hydrolysis and fermentation

Herein, the potential of watermelon rind (WMR) biomass for bio-ethanol production through an integrated bioprocess consisting of combinative sequential ultrasonication and deep eutectic solvent (DES) pretreatments, enzymatic hydrolysis and fermentation was investigated. For the improvement of the efficiency of the WMR conversion into bio-ethanol, the effectiveness of the ultrasonic-assisted DES pretreatment on bio-ethanol yield was studied by optimization, adopting Central Composite Rotatable Design. Glucose was the most dominant sugar in the WMR biomass which enhanced its suitability as cheap carbon source for fermentation process. Maximum glucose and total reducing sugar yields of 60.17% and 83.03% were respectively obtained, and the enzymatic hydrolysis efficiencies ranged from 75.79 to 91.13%. The bio-ethanol yield ranged from 0.276 to 0.458 gg−1 raw WMR, corresponding to fermentation efficiencies of 54.12–89.80%, with the maximum obtained at ultrasonication power 180 W, ultrasonication frequency 40 kHz, ultrasonication time 40 min, DES reaction temperature 120°C and DES reaction time 180 min. Results showed that all the pretreatment factors considered had significant effect on bio-ethanol yield. It was established that combinative pretreatment was efficient for delignification, solubilization and hydrolysis of cellulose and hemicellulose into monomeric sugars by removing hemicellulose from the cellulose fibers. This enhanced fermentable sugar recovery, which consequently increased bio-ethanol yield.

Metaproteomic Insights Into the Microbial Community in Pozol

Pozol is an acidic, refreshing, and non-alcoholic traditional Mayan beverage made with nixtamalized corn dough that is fermented spontaneously. The extensive analysis of the microbiology, biochemistry and metaproteomics of pozol allowed the construction of a comprehensive image of the fermentation system. The main changes in both the substrate and the microbiota occurred in the first 9 h of fermentation. The increase in microorganisms correlated with the drop in pH and with the decrease in the contents of carbohydrates, lipids, and nitrogen, which shows that this stage has the highest metabolic activity. Bacterial proteins were mainly represented by those of lactic acid bacteria, and among them, the proteins from genus Streptococcus was overwhelmingly the most abundant. Yeast proteins were present in all the analyzed samples, while proteins from filamentous fungi increased up to 48 h. The metaproteomic approach allowed us to identify several previously unknown enzyme complexes in the system. Additionally, enzymes for hydrolysis of starch, hemicellulose and cellulose were found, indicating that all these substrates can be used as a carbon source by the microbiota. Finally, enzymes related to the production of essential intermediates involved in the synthesis of organic acids, acetoin, butanediol, fatty acids and amino acids important for the generation of compounds that contribute to the sensorial quality of pozol, were found.

Complete and efficient conversion of plant cell wall hemicellulose into high-value bioproducts by engineered yeast

Plant cell wall hydrolysates contain not only sugars but also substantial amounts of acetate, a fermentation inhibitor that hinders bioconversion of lignocellulose. Despite the toxic and non-consumable nature of acetate during glucose metabolism, we demonstrate that acetate can be rapidly co-consumed with xylose by engineered Saccharomyces cerevisiae. The co-consumption leads to a metabolic re-configuration that boosts the synthesis of acetyl-CoA derived bioproducts, including triacetic acid lactone (TAL) and vitamin A, in engineered strains. Notably, by co-feeding xylose and acetate, an enginered strain produces 23.91 g/L TAL with a productivity of 0.29 g/L/h in bioreactor fermentation. This strain also completely converts a hemicellulose hydrolysate of switchgrass into 3.55 g/L TAL. These findings establish a versatile strategy that not only transforms an inhibitor into a valuable substrate but also expands the capacity of acetyl-CoA supply in S. cerevisiae for efficient bioconversion of cellulosic biomass.

Ammonia-assisted hydrothermal carbon material with schiff base structures synthesized from factory waste hemicelluloses for Cr(VI) adsorption

Nitrogen doping hydrothermal carbon material (NHTC) is an important metal ion adsorbent. In this work, NHTC with Schiff base structures (NHTC-SBS) was successfully synthesized via ammonia-assisted hydrothermal treatment of industrial hemicelluloses and used for the adsorption of toxic hexavalent chromium Cr(VI). The formation of Schiff base structures depends on the reaction between ammonia and furfural resulting from hemicelluloses hydrolysis. The morphology and structures of NHTC-SBS were characterized by SEM, XRD, BET, XPS and zeta potential. The results of adsorption experiments suggested that a high adsorption capacity of NHTC-SBS towards Cr(VI) was achieved at 349.6 mg/g according to Langmuir isotherm model under 298 K and pH 2.0. The adsorption of Cr(VI) on NHTC-SBS mainly depended on electrostatic attraction, redox, and chelation between nitrogen-containing groups (amino, Schiff base structures, heterocyclic nitrogen) and Cr(VI). This work provides a facial, green, and economical route to synthesize biochar with great adsorption performance.