Corn Straw Biochar Research Articles

Physicochemical modification of corn straw biochar to improve performance and its application of constructed wetland substrate to treat city tail water

Corn straw is rich in resources, and the preparation of biochar as the constructed wetland (CW) substrate is an effective measure to realize high-value resource utilization. The objective of this paper was to improve the treatment effect of CW on city tail water, the freeze-thaw cycles (FTCs) modification and chemical modification (KMnO4, NaOH and H2SO4) of straw biochar and the utilization of modified straw biochar in CW were studied. The modification characteristics of straw biochar were discussed through scanning electron microscope, element determination, pore structure determination, X-ray diffraction analysis, Fourier transform infrared reflection analysis, CO2 adsorption and desorption experiment and application experiment of CW (no plants and plants). The results show that under the influence of strong oxidation of KMnO4, the combination of KMnO4 and FTCs modification is easy to cause the destruction of biochar structure, and the content of carbon element is reduced. Except for the combined modification of NaOH and FTCs, other composite modifications have little effect on the crystal structure and functional groups of straw biochar. The adsorption capacity of CO2 by FTCs modified biochar increased by 20.4%, and the adsorption capacity of CO2 by H2SO4 and FTCs composite modified biochar increased by 23.0%. The effect of H2SO4 modification of straw biochar based on FTCs modification is obviously better than that of NaOH and KMnO4. The research results are of great significance to improve the material structure of biochar and the purification effect of CW on city tail water.

Sorption of Pb(II) onto biochar is enhanced through co-sorption of dissolved organic matter

Biochar plays an important role in controlling migration of pollutants in soils. However, little information is available on the interactions between soil-derived dissolved organic matter (DOM), biochar and soluble metal species. The aim of this work was to present the adsorption process of soil DOM by biochar (corn straw biochar produced at 700 °C) and to determine whether co-sorption of DOM would change the affinity for Pb(II). The adsorption rates of biochar and biochar + DOM for Pb(II) were best fitted with a pseudo-second order kinetic model, and the equilibrium adsorption isotherm data agreed well with both the Langmuir and Freundlich models. Adsorption of DOM to biochar reached equilibrium after 15 h with an uptake of 52% of the supplied DOM. We used fluorescence excitation-emission matrices (EEMs) with parallel factor (PARAFAC) analysis to demonstrate that protein-like, fulvic acid-like and humic acid-like substances were the primary constituents of the DOM, which were quenched over time in the presence of biochar. Synchronous fluorescence spectra indicated that the protein-like structures were the predominant fluorescence substances in DOM. Two-dimensional correlation spectroscopy (2D-COS) showed the binding of DOM to biochar resulted in the quenching of fluorescence in the order: protein-like substances > humic-like substances (280 > 355 nm). Data supports the notion that DOM can increase the adsorption capacity of biochar for metal-ions.

The co-addition of biochar and manganese ore promotes nitrous oxide reduction but favors methane emission in sewage sludge composting

In the present study, the effects of biochar and manganese ore (MO) on N2O and CH4 emissions during sewage sludge composting were investigated. The results demonstrated that the additive additions could effectively reduce total nitrogen loss and improve the agronomic value of compost. Furthermore, all the additive treatments could mitigate N2O (6.60–45.9%) and CH4 (33.6–71.3%) emissions. Compared to the single corn straw biochar (CSB) or MO addition, the co-addition of CSB and MO can further promote N2O reduction by 14.6–22.4% but increase CH4 emission by 22.9–33.7%. Overall, the co-addition of CSB and MO showed the lowest global warming potential, which was 42.1% lower than the control, among all the additive treatments. Integrating the analyzed results of Spearman rank correlation coefficients and functional genes, the inhibition of N2O generation during nitrification and denitrification processes was identified as the main mechanism for the reduced N2O emissions. For CH4, the reduced CH4 emissions were contributed by simultaneously inhibiting CH4 generation and promoting CH4 consumption, especially for the single CSB or MO treatments. Additionally, based on the analyzed results of the structural equation model, amoA and nirS were found to be the key functional genes affecting N2O emissions directly, and temperature and pH were identified as the root factors affecting N2O emissions through varied biological or chemical pathways. These findings could provide a new alternative to produce high-quality sewage sludge compost with lower environmental impact in an economical way.

Preparation of magnetic chitosan corn straw biochar and its application in adsorption of amaranth dye in aqueous solution

In this study, the magnetic chitosan biochar (MCB) was magnetized by chemical coprecipitation after loading chitosan with Schiff base reaction. The prepared MCB was used to remove amaranth dye in solution. The synthesized MCB was characterized to define its surface morphology and specific elements. The amaranth dye adsorption system was optimized by varying the contact time, pH, and initial concentration. The adsorption of MCB on amaranth dye was measured in a wide pH range. According to Zeta potential, the surface of MCB was positively charged in the acidic pH region, which was more conducive to the adsorption of anionic amaranth dye. In addition, the adsorption data was fitted with the pseudo-first-order model and Langmuir adsorption model and the maximum adsorption capacity reached 404.18 mg/g. The adsorption efficiency of MCB was still above 95% after three cycles of adsorption and desorption. The removal percentage in the real sample of amaranth dye by MCB was within 94.5–98.6% and the RSD was within 0.14–1.08%. The MCB adsorbent with advantages of being easy to prepare, easy to separate from solution after adsorption, has good adsorption performance for amaranth dye and is effective potential adsorbent to remove organic anionic dye in wastewater.

Nano zero-valent iron loaded corn-straw biochar for efficient removal of hexavalent chromium: remediation performance and interfacial chemical behaviour.

To improve the poor stability of nano zero-valent iron (nZVI), corn-straw biochar (BC) was used as a support for the synthesis of composites of nZVI-biochar (nZVI/BC) in different mass ratios. After a thorough characterization, the obtained nZVI/BC composite was used to remove hexavalent chromium [Cr(vi)] in an aquatic system under varying conditions including composite amount, Cr(vi) concentration, and pH. The obtained results show that the treatment efficiency varied in the following order: nZVI-BC (1 : 3) > nZVI-BC (1 : 5) > nZVI alone > BC alone. This order indicates the higher efficiency of composite material and the positive effect of nZVI content in the composite. Similarly, the composite dosage and Cr(vi) concentration had significant effects on the removal performance and 2 g L-1 and 6 g L-1 were considered to be the optimum dose at a Cr(vi) concentration of 20 mg L-1 and 100 mg L-1, respectively. The removal efficiency was maximum (100%) at pH 2 whereas solution pH increased significantly after the reaction (from 2 to 4.13). The removal kinetics of Cr(vi) was described by a pseudo-second-order model which indicated that the removal process was mainly controlled by the rate of chemical adsorption. The thermodynamics was more in line with the Freundlich model which indicated that the removal was multi-molecular layer adsorption. TEM-EDS, XRD, and XPS were applied to characterize the crystal lattice and structural changes of the material to specify the interfacial chemical behaviour on the agent surface. These techniques demonstrate that the underlying mechanisms of Cr(vi) removal include adsorption, chemical reduction-oxidation reaction, and co-precipitation on the surface of the nZVI-BC composite. The results indicated that the corn-straw BC as a carrier material highly improved Cr(vi) removal performance of nZVI and offered better utilization of the corn straw.

Enhanced performance and microbial communities of anaerobic digestion with biochar in pilot-scale continuous stirred-tank reactors: effects of substrate concentration and hydraulic retention time

AD was enhanced with low-cost corn straw biochar in 16 L CSTRs, and the highest biogas production rate was 1.41 L L−1 d−1 at a substrate concentration of 12%. Methanosarcina showed a better performance in relieving ammonia nitrogen inhibition.

The potential of using corn straw biochar to compensate the loss of available soil organic matter

The process of migration of organic carbon from the biochar into the substrate and the aqueous phase was simulated. The process of organic carbon migration in passive and washing mode was evaluated. Part of the organic carbon was washed with water and passed into the aqueous phase, the other part remained in the mass of biochar. Biochar can be a source of available organic carbon, providing nutrition to rhizosphere microorganisms that improve the mineral nutrition of plants, both in the short and long term.

Enhanced adsorptive removal of carbendazim from water by FeCl3-modified corn straw biochar as compared with pristine, HCl and NaOH modification

Carbendazim residues were widely present in the worldwide water which caused a potential risk to water ecosystem and human health. Therefore, it is necessary to develop environmentally friendly ways to eliminate its residue in the contaminated water environments. Herein, the corn straw biochars were prepared at 300 (BC300), 500 (BC500), and 700 °C (BC700). Moreover, using BC700 as precursor, three novel adsorbents of acid, alkali, and iron magnetization modified biochar (named as BC700H, BC700N, and BC700M, respectively) were synthesized to adsorptive removal of carbendazim from water. Results showed that the adsorption capacity of six biochar materials for carbendazim was in the following order BC700M>BC700H>BC700N>BC700 >BC500 >BC300. The maximum adsorption amount of BC700M reached up to 108.1 mg g−1. The adsorption of carbendazim was a spontaneous, endothermic, and randomly increasing process, while both physisorption and chemisorption were involved in adsorption process for all prepared biochar materials. For BC700M, pore filling, π-π interaction, oxygen-containing groups, and Fe-O complexation were main mechanisms. The BC700M can be easily separated and regenerated at least five times under a wide pH range. Overall, as compared to the other five biochar materials, this study indicates that Fe-modified corn straw biochar is a promising and sustainable adsorbent for carbendazim removal from water environment.

Base cation‐enhancing role of corn straw biochar in an acidic soil

AbstractBiochar affects base cation retention and leaching when it is used to enhance the base cation status of acidic soil. However, the details of its contribution are not yet clear. In this study, six loadings of corn straw biochar (0%, 2%, 4%, 6%, 8% and 10%, w/w) were applied to an acidic Ferralsol and incubated for 1 year. The results showed that the content of water‐soluble and exchangeable base cations of K, Na, Ca and Mg increased with increasing levels of biochar in amended soil. The percentage of water‐soluble Na, Ca and Mg of amended soil significantly decreased, while the percentage of exchangeable K, Ca and Mg increased significantly after the addition of biochar. For K and Na, biochar affected their leaching concentrations both as a source and by increasing the pH. For Ca, biochar reduced Ca leaching when the biochar loading was ≥4%, and the contribution increased from 30.8% to 100% at 4%–10% loading. For Mg, biochar reduced Mg leaching at biochar loadings 2%–10%, the reduction increasing from 22.0% to 70.5%. The results show that corn straw biochar can increase the content of the soil nutrient base cations K, Ca and Mg by increasing their exchangeable forms and enhance soil retention by decreasing their leaching. Thus, corn straw biochar can be used to effectively improve acidic soil base cation fertility.

Development and Optimization of Bioretention Systems with Modified Fillers of Corn Straw Biochar

Development and Optimization of Bioretention Systems with Modified Fillers of Corn Straw Biochar

Impact of Different Biochars on Microbial Community Structure in the Rhizospheric Soil of Rice Grown in Albic Soil.

The purpose of this study was to clarify the effects of biochar on the diversity of bacteria and fungi in the rice root zone and to reveal the changes in soil microbial community structure in the root zone after biochar application to provide a scientific basis for the improvement of albic soil. Rice and corn stalk biochar were mixed with albic soil in a pot experiment. Soil samples were collected at the rice maturity stage, soil nutrients were determined, and genomic DNA was extracted. The library was established using polymerase chain reaction (PCR) amplification. The abundance, diversity index, and community structure of the soil bacterial 16SrRNA gene V3 + V4 region and the fungal internal transcribed spacer-1 (ITS1) region were analyzed using Illumina second-generation high-throughput sequencing technology on the MiSeq platform with related bioinformatics. The results revealed that the biochar increased the soil nutrient content of albic soil. The bacteria ACE indexes of treatments of rice straw biochar (SD) and corn straw biochar (SY) were increased by 3.10% and 2.06%, respectively, and the fungi ACE and Chao indices of SD were increased by 7.86% and 14.16%, respectively, compared to conventional control treatment with no biochar (SBCK). The numbers of bacterial and fungal operational taxonomic units (OUT) in SD and SY were increased, respectively, compared to that of SBCK. The relationship between soil bacteria and fungi in the biochar-treated groups was stronger than that in the SBCK. The bacterial and fungal populations were correlated with soil nutrients, which suggested that the impacts of biochar on the soil bacteria and fungi community were indirectly driven by alternation of soil nutrient characteristics. The addition of two types of biochar altered the soil microbial community structure and the effect of rice straw biochar treatment on SD was more pronounced. This study aimed to provide a reference and basic understanding for albic soil improvement by biochar, with good application prospects.

Preparation and characterization of biochar derived from co-pyrolysis of Enteromorpha prolifera and corn straw and its potential as a soil amendment

Single biomass feedstock approach may not meet the requirements for developing biochar with desired characteristics for use as soil amendment. In this study, biochars were prepared by co-pyrolysis of nutrients-rich Enteromorpha prolifera and lignocellulose-rich corn straw (CPECs) at different mass ratios (3:7, 1:1, and 7:3). CPECs presented higher water-soluble N/P contents than corn straw biochar, and exhibited larger surface area, low Na content, and slower nutrient release rate than Enteromorpha prolifera biochar. The modification in physicochemical and properties of CPECs enhanced its potential application as a soil amendment. A pot experiment showed that CPECs derived from co-pyrolysis of appropriate ratios of Enteromorpha prolifera and corn straw (1:1, 7:3) significantly increased the biomass of cherry tomato plant by 64.05%, 40.03% and 81.88%, 55.25%, when compared with corn straw biochar and Enteromorpha prolifera biochar, respectively. The positive effects of CPECs were primarily attributed to improved soil properties (e.g., water holding capacity, soil organic matter, pH, soil nutrients content) and increased total N/P uptake by plants. The results of this work provided potentials of developing “designer” biochars to meet the multiple soil requirements by co-pyrolysis.

Effects of different straw biochar combined with microbial inoculants on soil environment in pot experiment

Ginseng is an important cash crop. The long-term continuous cropping of ginseng causes the imbalance of soil environment and the exacerbation of soil-borne diseases, which affects the healthy development of ginseng industry. In this study, ginseng continuous cropping soil was treated with microbial inocula using broad-spectrum biocontrol microbial strain Frankia F1. Wheat straw, rice straw and corn straw were the best carrier materials for microbial inoculum. After treatment with microbial inoculum prepared with corn straw biochar, the soil pH value, organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium were increased by 11.18%, 55.43%, 33.07%, 26.70%, 16.40%, and 9.10%, the activities of soil urease, catalase and sucrase increased by 52.73%, 16.80% and 43.80%, respectively. A Metagenomics showed that after the application of microbial inoculum prepared with corn straw biochar, soil microbial OTUs, Chao1 index, Shannon index, and Simpson index increased by 19.86%, 16.05%, 28.83%, and 3.16%, respectively. Three classes (Alphaproteobacteria, Gammaproteobacteria and Sphingobacteria) were the dominant bacteria in ginseng soil, and their abundance increased by 7.87%, 9.81% and 1.24%, respectively, after treatment with microbial inoculum with corn straw biochar. Results indicated that the most effective treatment in ginseng soil would be the combined application of corn straw biochar and Frankia F1.

Effects of Biochar on Sediment Transport and Rill Erosion after Two Consecutive Years of Seasonal Freezing and Thawing

This research explored the effects of biochar on slope runoff and sediment transport processes and the hydrodynamic mechanism of rill erosion under the seasonal freeze–thaw climate in the black soil area of Northeast China. The four slopes of 1.8, 3.6, 5.4 and 7.2° were set, corn straw biochar was used, and three biochar contents of 0 kg m−2 (B0 treatment), 6 kg m−2 (B6 treatment) and 12 kg m−2 (B12 treatment) were applied. The experimental plot was placed outdoors to simulate the freeze–thaw cycle of sloping farmland under natural conditions. Three artificial simulated rainfall tests were carried out before the end of seasonal freeze–thaw cycles and spring sowing date (May) in 2018 and 2019. The sediment transport process of runoff and the variation of hydrodynamic parameters in rills were analyzed under one and two seasons of freezing and thawing in natural outdoor conditions. The results show that biochar has a positive effect on reducing rainfall runoff and soil loss after one year and two years of seasonal freezing and thawing. The effect of biochar on the sediment concentration of slope runoff increased with increasing application time; in the second year, the B6 and B12 treatments reduced the sediment concentration by 5.5–14.8% and 3.3–13.6%, respectively, compared with the values of the first year. The Reynolds number (Re) in the rill flow after the B6 and B12 treatments decreased with increasing duration, which effectively reduced the turbulence degree of the flow on the rill of the slope. With the increase in duration, the rill critical erosion power increased; in 2018 and 2019, the critical shear force, critical runoff power and critical unit runoff power were 0.403 Pa, 0.098 m s−1, and 0.002 N m−1 and 0.497 Pa, 0.124 m s−1, and 0.003 N m−1, respectively. This result indicates that increasing the duration and number of seasonal freeze–thaws can promote the development of biochar control of the runoff and sediment processes on slope and rill development.

The Adsorption Characteristics and Mechanism of Pb(II) onto Corn Straw Biochar

Heavy metal pollution has adversely affected the ecological environment. As an eco-friendly and renewable material, biochar has a positive effect on environmental restoration. For study the feasibility of removing lead using corn straw biochar, the adsorption characteristics and mechanism were studied. This work prepared corn straw biochar at 300 °C, and its surface properties were characterized. The adsorption kinetics, isotherm, thermodynamics were determined. The result indicated the mechanism belonged ion exchange and complexation, and the experiment were controlled by comprehensive process, which included reaction rate and diffusion. The Langmuir model had better fitting results for the adsorption data, which indicated that adsorption was chemical adsorption and single molecular layer adsorption, and the maximum adsorption amount of corn straw biochar at 25 °C, 35 °C and 45 °C were 81.63 mg/g, 83.89 mg/g and 89.21 mg/g respectively. The thermodynamic analysis showed that increasing temperature was helpful to adsorption, and the adsorption was spontaneous. The results can be used for comprehensive utilization of straw and treatment of lead pollution.

Removal of chlortetracycline from water by immobilized Bacillus subtilis on honeysuckle residue–derived biochar

Biochar-immobilized microorganism technology is an effective way to remove antibiotic contamination in aqueous solutions. In this study, the effect and mechanism of immobilization of Bacillus subtilis by honeysuckle residue–derived biochar for the removal of chlortetracycline (CTC) were investigated using corn straw biochar as a comparison. The biochar’s structural characteristics and properties were determined using scanning electron microscopy, X-ray diffractometer, Fourier-transform infrared spectrometer, specific surface area, and pore size analyzer. It was found that honeysuckle residue–derived biochar had a well-developed pore structure, which provided adequate living space for microorganisms. The removal rate of CTC (50 mg/L) by honeysuckle residue biochar-microbial complex (HBCM) was 15.31% higher than that of corn straw biochar-microbial complex, indicating that HBCM was an excellent carrier. The mechanism of CTC removal by HBCM was a synergistic effect of biochar adsorption and microbial degradation. The removal process of HBCM material was carried out for 3 days at an optimum substrate concentration of 50 mg/L, an ambient temperature of 35 °C, a solution pH of 7, and the addition of 5 g/L complexes, achieving a removal rate of 78.35%. In addition, the complex possessed high storage stability and could be reused three times continuously and efficiently. This study provides a method for preparing an efficient biochar-microbial complex using Chinese medicine residue waste substrate, which provides a new idea for removing CTC from water.

Role of biochar from corn straw in influencing crack propagation and evaporation in sodic soils

Soil degradation has become one of the serious global environmental problems, biochar is a recyclable natural material which has been widely used in soil remediation. Soil cracking can significantly change the migration path of water and nutrients in the soil, which affects the remediation performance of biochar and plant growth. The effects of different amounts of corn straw biochar on the evaporation and drying shrinkage characteristics of sodic soil are investigated in this paper. Different amounts (by mass) of biochar: 0%, 1%, 2%, 4% and 8% are added to the soil. A customized experimental device is used to measure the rate of evaporation of water and record the images of surface crack development of the samples during drying. Using image processing technology, the crack rate, crack entropy and fractal dimension of the cracks are obtained. The experimental results show that: (1) biochar can change the drying and cracking characteristics of sodic soil by changing the evaporation process of the soil. With biochar contents of 1%, 2%, and 4%, the residual water contents of soil samples are decreased by 4.83%, 43.94% and 85.71%, respectively. With an 8% biochar content, the residual water content of soil sample is increased by 64.49%, (2) the addition of biochar reduces the rate of cracking and fractal dimension of sodic soil. With an 8% biochar content, the rate of cracking and fracture fractal dimension are reduced by 46.39% and 13.74%, respectively, (3) the addition of biochar can effectively reduce the degree of the disorderly arrangement of surface cracks. At biochar contents of 2%, 4% and 8%, the crack entropies are decreased by 2.22%, 6.46% and 7.37%, respectively, and (4) the mechanisms in which biochar changes crack development in sodic soil are: (a) improving the soil texture and reducing the bulk density of soil and (b) increasing the number of water migration channels, soil aggregates and the water retention capacity in the soil.

Facile synthesis of eggshell biochar beads for superior aqueous phosphate adsorption with potential urine P-recovery

Phosphorus (P) uptake from wastewater is a widespread concern due to the concurrent issues of P contamination and deficiency. A corn straw biochar-based eggshell bead composite (CS-E0.25-Ca(b)) was innovatively synthesized via a facile gelation-calcination method for efficient P recovery from urine solutions. Batch adsorption experiments showed that CS-E0.25-Ca(b) fabricated under optimal conditions exhibited a superior adsorption capacity (136.83 mg/g), which was 29.93 and 6.77 times that of pristine biochar (CSBC) and bead without the addition of eggshell respectively. CS-E0.25-Ca(b) exhibited favorable adsorption performance at pH 6.0–9.0 and in the presence of coexisting anion conditions, and showed good mass transfer performance in urine environment. Characterization results indicated that corn straw biochar matrix can lead to porous internal structure, which could facilitate better dispersion of CaO/Ca(OH)2 in eggshell to adhere on CS-E0.25-Ca(b). The comparison of FTIR and XPS analyses revealed that the surface precipitation with Ca-P products of hydroxyapatite (HAP) and amorphous calcium phosphate (ACP) was the predominant mechanism of phosphorus adsorption on CS-E0.25-Ca(b). In the slow-releasing experiment, the urine P-saturated CS-E0.25-Ca(b) displayed controllable and long-term slow-releasing property in neutral solution. Besides, CS-E0.25-Ca(b) after P release displayed favorable adsorption performance for common heavy metals, showing potential extra benefit for remediating heavy metal contaminated soils. All the results suggested that CS-E0.25-Ca(b) can realize superior P uptake from urine, also be potentially qualified as a promising slow-releasing fertilizer for soil P supply.

Immobilization of soil Cd (II) by modified biochars

Adsorption kinetics and isotherms of Cd2+ onto different types of biochar are studied in batch experiments. Three types of biochar (rice, wheat and corn straw biochar) and their phosphate or chitosan modified materials were used in this study. Results showed that Langmuir equation can better describe the adsorption isotherms of Cd2+ onto these biochars (r2 > 0.960). Among different types of biochars, rice straw biochar (RB) and its chitosan modified biochar (CRB) had highest adsorption capacity of Cd2+. RB, wheat straw biochar (WB) and their modified biochars were used to remediate Cd-contaminated soil. Soil pH values increased with the increasing of biochar dosage and chitosan modified biochar amended soil had the highest soil pH values. Contents of DTPA extractable Cd in soil decreased with the increase of biochar dosage and incubation time. Among different types of biochars, 5% CRB amended soil at 60 days of incubation had the lowest content of DTPA extractable Cd. This study showed that the application of modified biochars can effectively alleviate soil Cd contamination.

Bisphenol A adsorption behavior on soil and biochar: impact of dissolved organic matter.

Dissolved organic matter (DOM) released from soil (SDOM) and biochar (BDOM) plays an important role in the fate of pollutants for the application of biochar in soil remediation. However, little attention has been paid to the impact of DOM on the adsorption of soil and/or biochar-bisphenol A (BPA) system. Hence, batch sorption experiments combined with quenching titration experiments were processed to reveal these behaviors and complexation mechanisms based on red soil and corn straw biochar. Moreover, multiple spectral technologies and methods were also introduced including ultraviolet-visible, three-dimensional excitation-emission matrix, synchronous fluorescence spectrum, two-dimensional correlation spectroscopy (2D-COS), and parallel factor analysis. Isothermal adsorption results showed that the non-linearity and the adsorption capacity both increased after the addition of biochar, indicating that biochar could improve the surface adsorption capacity of the sorption system. Besides, the sorption capacity of BPA decreased for soil while increased for biochar after removal of the water-extractable DOM. 2D-COS analysis showed that the protein-like components preferentially occurred for both SDOM and BDOM under BPA surrounding. In addition, C2 (humic-like), C4 (tyrosine-like), and C5 (tryptophan-like) in the two DOMs were all involved in the quenching reaction with BPA, with C4 and C5 having higher quenching degree than C2, suggesting that protein-like substances had stronger affinity quenching effect with BPA. This study highlighted the significance of fluorescence property for DOM, which can extend the knowledge of the fate of pollutants in the application of biochar.