Query: Modified biochar； soil heavy metal pollution

title: Enhanced Heavy Metal Removal from Synthetic Stormwater Using Nanoscale Zerovalent Iron Modified Biochar
abstract: The use of biochar for removal of heavy metals from stormwater is limited due to large area requirements and inadequate removal of nutrients and heavy metals at higher initial concentrations. In this study, biochar supported nanoscale zerovalent iron (BC nZVI) was effectively utilized for removing heavy metals from synthetic stormwater. We performed batch adsorption and laboratory scale column experiments to demonstrate the exceptional ability of BC nZVI to remove heavy metals (Cu, Cd, and Zn) at varying higher initial concentration range (2.5 to 60 mg L 1 compared with typical urban stormwater runoff. The batch experiment results suggested that the metal removal efficiency of BC nZVI compared with biochar was enhanced by 43% and 57% in individual metal solution and 50% and 42% in the mixed metal solution for Cd and Zn, respectively. The maximum adsorption capacities of BC nZVI for individual metal ions increased by 97% and 40% for Cd 2+ and Zn 2+ respectively, compared with original biochar. A series of characterization studies based on scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer Emmett Teller revealed the chemical and morphological features of BC nZVI, which are responsible for the enhanced metal removal. A laboratory scale column study mimicking the field scale revealed the metal removal efficiencies of BC nZVI increased by 115% and 123% for Cd 2+ and Zn 2+ respectively, compared with unmodified biochar. The higher removal efficiencies and adsorption capacities demonstrate the potential use of BC nZVI as a media for attenuating heavy metals in current stormwater management practices.

title: Effects of Fe Mn Ce oxide modified biochar on As accumulation, morphology, and quality of rice (Oryza sativa L.
abstract: The fluidity of arsenic (As) in soil used for rice cultivation under flooding conditions is the main reason for its high accumulation in rice, which poses a serious threat to human's health. Biochar can immobilize heavy metal (for example lead) of soil because of the strong binding of heavy metals to the inner biochar particles. We conducted a pot experiment to evaluate the effects of biochar (BC) and Fe Mn Ce oxide modified biochar composites (FMCBCs) on the morphology, As accumulation, and grain quality of rice grown in As contaminated soils. The biochar and FMCBC treatments significantly increased the dry weight of roots, stems, leaves, and rice grains grown in As contaminated soil (P 0.05) The As concentration in different parts of rice was significantly lower with treatment FMCBC3 2 (BC, Fe, Mn, and Ce weight ratio of 24:2:3:10) than with the BC and control (no BC) treatments. The application of FMCBC3 2 maximized the yield and quality of rice grains: rice grain yields were 61.45 68.41% higher over control and the proportion of essential amino acids in the rice grains was 31.01 44.62% The application of FMCBCs also increased the concentration of Fe Mn plaques, which prevent the uptake of As by rice, thereby mitigating the toxic effects of As contaminated soil on rice. In summary, Fe Mn Ce oxide modified BC composites fixed As, reducing its fluidity and the As concentration in rice. Our results show that FMCBC3 could play an important role in reducing As accumulation and increasing the grain yield and quality of rice, thus ensuring food safety in regions contaminated with As.

title: Removal Characteristics of Heavy Metal ions in Rainwater Runoff by Bioretention Cell Modified with Biochar.
abstract: As a form of pollution source control and a low impact development measure, bioretention is a convenient, economical and effective method for the removal of heavy metals from stormwater runoff, which can adapt to the randomness and uncontrollability of non point source pollution. However, few studies have assessed the performance of bioretention in the simultaneous removal multiple heavy metals and the impact of heavy metal migration on the bioretention life cycle. In this study, the removal rates of various heavy metals: copper (Cu) zinc (Zn) lead (Pb) and cadmium (Cd) were enhanced using a biochar modified bioretention cell, as compared to the traditional sandy soil bioretention process. Following treatment with the biochar modified bioretention cell, the average concentrations of Cu, Zn, Pb, and Cd were 55% 61% 19.66% and 36.43% lower than the traditional sandy soil bioretention effluent, respectively. These results show that biochar significantly improves the removal of heavy metals in by the bioretention process, especially Cu and Zn. This study also evaluated the effect of biochar on the inhibition of heavy metal migration in the filler material, by sampling and analyzing the filler and retained water at different filler depths, then repeating the filler leaching experiment after simulated rainfall. The content of heavy metals at a filler depth of 45 cm in the traditional sandy soil bioretention system, was significantly higher than in the biochar modified bioretention system, showing that biochar plays an important role in the inhibition of heavy metal migration.

title: Remediation of antibiotic and heavy metal pollution in marine environment
abstract: <p>Pollution of marine environment by antibiotics and/or heavy metals is a serious global issue. Remediation of polluted marine environments is urgently needed for achieving the United Nations Sustainable Development Goals (SDGs) to end poverty and protect the planet from degradation. Biochar, as an environmentally friendly material, has been widely used as adsorbents to remediate contaminated soil or fresh water. However, application of biochar in remediation of marine environment is poorly understood. Therefore, a batch of biochars produced from pyrolysis of two marine algae residues, Enteromorpha (Enteromorpha prolifera) and blended seaweed wastes, at 300&#8211;700 #176;C was used to investigate their performance in sulfamethoxazole (SMX) sorption in seawater. Additionally, a modified biochar (MBC) was prepared by pyrolyzing AlCl<sub>3</sub> pretreated sawdust to improve their performance in remediating a marine sediment contaminated with heavy metals and antibiotics using two mesocosmic experiments. The results showed the algae derived biochars had relatively low C content, but high contents of O and S containing functional groups and crystalline minerals associated with S, Ca, K, and Mg. The maximum adsorption capacity of these algae derived biochars to SMX was 4880 mg kg<sup> 1</sup> equivalent to a commercial coconut shell derived activated carbon. Potential mechanisms responsible for the SMX sorption mainly included pore filling, cation bridging, negative charge assisted H bond #8211;)CAHB] and #960; #960; EDA interaction. The surface of MBC was rough with layered homogeneous sheets, and the nano scale Al minerals formed on the C matrix. Moreover, its settling properties and adsorption capacities to Cu, Cd, SMX, and tetracycline (TC) were highly improved relative to the unmodified sawdust derived biochar (SBC) As a result, addition of MBC at 4% (w/w) performed #160;better in improving the survival rate and condition index of the clams in the contaminated sediments than SBC. Furthermore, MBC application decreased bioaccumulation of Cu and Cd in the clams. Both SBC and MBC increased the microbial abundance and diversity in the contaminated sediments, and MBC decreased the abundance of Cu resistant bacteria (e.g. Firmicute and Gemmatimonadetes) For the sediment contaminated by antibiotics, lower content of SMX and TC in the overlying water and pore water was observed in the sediment amended with MBC than SBC, leading to the reduction of total antibiotic resistance genes. Therefore, these findings show the potential of functional/modified biochar to remediate marine sediments contaminated with heavy metals and antibiotics./p>

title: Remediation of arsenic contaminated soil by nano zirconia modified biochar
abstract: Nowadays, the soil arsenic pollution is considered as a serious environmental issue, and the high toxicity of arsenic can seriously affect the quality and safety of agricultural products and human health. Biochar, as a solidifying/passivating agent, has been widely used in the treatment of soil heavy metal pollution. Pine biochar (BC) was used as a carrier in this study, and biochar loaded nano zirconia (N ZrO2 BC) was synthesized to investigate its adsorption and fixation characteristics on As (V) in soil and water. The adsorption experiment showed that the second order kinetic equation had a good fitting effect on the adsorption curve of As (V) on the N ZrO2 BC surface, which indicated that chemical adsorption was the main factor controlling the reaction rate. FTIR and SEM results showed that ion exchange and surface complexation were the main mechanisms of As (V) adsorption by N ZrO2 BC. Soil culture experiments showed that the stabilization efficiency of arsenic in soil with 2% N ZrO2 BC reached 99.30% after 60 days, and the extractable arsenic content was reduced to 3.07 mg*L 1, which reached the quality standard of class III groundwater <0.01 mg*L 1, GB/T 14848 2017) Comparing with the control, the content of acid extractable arsenic in soil decreased by 90.57% and the residual arsenic increased by 51.46% indicating that the addition of N ZrO2 BC could effectively promote the transformation of active arsenic to stable arsenic in soil.

title: Restoration of heavy metal contaminated soil and water through biosorbents: A Review of Current understanding and future challenges.
abstract: Heavy metal pollution in soil and water is a potential threat to human health as it renders food quality substandard. Different biosorbents such as microbial and agricultural biomass have been exploited for heavy metal immobilization in soil and sorptive removal in waters. Biosorption is an effective and sustainable method for heavy metal removal in soil and water, but the inherent challenges are to find cheap, selective, robust, and cost effective bioadsorbents. Microbial and agricultural biomass and their modified forms such as nanocomposites, carbonaceous materials (viz. biochar, nanobiochar, biocarbon) might be useful for sequestration of heavy metals in soil via adsorption, ion exchange, complexation, precipitation and enzymatic transformation mechanisms. In this review, potential biosorbents and their metal removal capacity in soil and water are discussed. The microbial adsorbents and modified composites of agricultural biomasses show improved performance, stability, reusability, and effectively immobilize heavy metals from soil and water. In the future, researchers may consider the modified composites, encapsulated biosorbents for soil and water remediation. This article is protected by copyright. All rights reserved.

title: Adsorption characteristics of modified rice straw biochar for Zn and in situ remediation of Zn contaminated soil
abstract: Remediation of heavy metal pollution in farmland soil is very important to protect human health and ecological security, and biochar has a certain adsorption and fixation effect on soil heavy metals. In this paper, three kinds of biochar (unmodified biochar, acid modified biochar and biochar from pyrolysis of alkali modified rice straw, abbreviated as RBC, HRBC and KRBC, respectively) were prepared from rice straw, the surface morphology characteristics of RBC, HRBC and KRBC were characterized with SEM scanning, BET specific surface area measurement and porosity measurement and the adsorption characteristics of Zn in/on the three kinds of biochar and the in situ immobilization effect for the soil Zn were investigated through the laboratory simulation. The results showed that KRBC had larger specific surface area, richer porosity, more oxygen containing functional groups on the surface, as well as higher aromaticity and carbonization degree than that of RBC and HRBC; the adsorption kinetic characteristics of Zn in RBC, HRBC and KRBC were fitted well with the quasi second order kinetic model and the adsorption thermodynamic characteristics of Zn in RBC, HRBC and KRBC could be described well with both the models of Langmuir and Freundlich, the maximum adsorption capacity of Zn was the order of KRBC>RBC>HRBC; KRBC had the strongest immobilization ability for Zn in soil, which was related to the strongest ability of KRBC to improve soil pH and soil organic carbon. Therefore, biochar from pyrolysis of alkali modified rice straw (KRBC) was being of the significant immobilization remediation effect on soil Zn pollution. This study can provide theoretical and technical support basis for remediation of Zn contaminated soil.

title: An efficient biochar synthesized by iron zinc modified corn straw for simultaneously immobilization Cd in acidic and alkaline soils.
abstract: Synthetic functional biochar using agricultural waste as raw materials not only serves as an effective means for recycling waste but can also be employed for the remediation of heavy metal contaminated soil. However, the associated effect and mechanism underlying the immobilization of functional biochar in acidic and alkaline soils remain unclear. In this study, a novel iron zinc oxide composite modified corn straw (Fe/Zn YBC) was prepared and applied for the remediation of cadmium contaminated acidic and alkaline farmland soils. The results showed that the addition of Fe/Zn YBC increased the pH, cation exchange capacity (CEC) and dissolved organic carbon (DOC) in acidic soil, while increased the pH and DOC in alkaline soil. After immobilization for 42 d, the DTPA Cd content in acidic and alkaline soils treated with Fe/Zn YBC decreased by 12.77 57.45 and 23.73 52.50 respectively. Fe/Zn YBC treatment promoted the transformation of the exchangeable fraction into the Fe/Mn oxyhydroxide fraction of Cd, and increased the abundance and diversity of bacterial communities in the two soils. Furthermore, the SEM EDS, XRD and FTIR results for Fe/Zn YBC separated from the test soils showed that the distribution of Cd adsorbed on Fe/Zn YBC was positively correlated with Fe, Zn, and O. Additionally, the Cd complexes (CdCO3, CdZnFe2O4 and CdO) detected on Fe/Zn YBC indicated that the primary immobilization mechanism of Fe/Zn YBC involved the complexation of Cd and Fe, Zn oxides, and the precipitation of Cd and CO32 in acidic and alkaline soils. The efficient remediation capacity and associated mechanism for this novel functional biochar provide insights for improved remediation of heavy metal contaminated farmland soil.

title: [Characteristics of Modified Biochars and Their Immobilization Effect on Cu and Cd in Polluted Farmland Soil Around Smelter]
abstract: Heavy metals in farmland soil are one of the most hazardous pollutants in the environment, owing to their universality and irreversibility. Modified biochar has been widely used in the adsorption and immobilization of heavy metals in soil, and its applicability is mainly determined by the types of heavy metals, pollution levels, and soil environmental conditions. Soil pollution is gradually becoming more complex and diversified, and heavy metal pollutants mostly occur in the form of compound pollution. However, most studies have focused on single heavy metal pollutant or the addition of heavy metal to soil. This study used rice straw as a raw material to prepare biochar, and modified it with K3PO4, KMnO4, and NaOH. The physicochemical and structural characteristics of the modified biochars were detected using a BET accelerated surface area and porosimetry system, scanning electron microscopy (SEM) Fourier transform infrared spectroscopy (FT IR) and the biochars were then analyzed for the availability and forms of Cd and Cu in soils contaminated with heavy metals in the mining area. The results showed that the surface roughness of the modified biochar increased to different degrees with increases in specific surface area and pore volume, with the NaOH modified biochar showing the most significant increases from 4.96 m2*g 1 to 60.79 m2*g 1, and from 0.02 cm3*g 1 to 0.12 cm3*g 1, respectively. The pore diameter changed in the opposite direction. The absorption peaks of the functional groups of the modified biochar were all changed, with K3PO4 modified biochar exhibiting the greatest degree of change. The addition of biochar significantly improved the soil pH value (P<0.05) and the pH value of the soil treated with K3PO4 modified biochar exhibited the largest increase. With an application of 20.5% K3PO4 modified biochar, the availability of Cu and Cd in the soil was significantly reduced, by 75.44% and 67.70% respectively. The immobilization efficiency of Cu was much higher than that of Cd. The best immobilization efficiency of Cu and Cd in soil was achieved with K3PO4 modified biochar. With an addition of 2% K3PO4 modified biochar, the immobilization efficiency of Cu and Cd was 61.06% and 4.12% respectively. In summary, K3PO4 modified biochar had a better immobilization effect on both Cu and Cd in compound contaminated soil.

title: A modified receptor model for source apportionment of heavy metal pollution in soil.
abstract: Source apportionment is a crucial step toward reduction of heavy metal pollution in soil. Existing methods are generally based on receptor models. However, overestimation or underestimation occurs when they are applied to heavy metal source apportionment in soil. Therefore, a modified model (PCA MLRD) was developed, which is based on principal component analysis (PCA) and multiple linear regression with distance (MLRD) This model was applied to a case study conducted in a peri urban area in southeast China where soils were contaminated by arsenic (As) cadmium (Cd) mercury (Hg) and lead (Pb) Compared with existing models, PCA MLRD is able to identify specific sources and quantify the extent of influence for each emission. The zinc (Zn) Pb mine was identified as the most important anthropogenic emission, which affected approximately half area for Pb and As accumulation, and approximately one third for Cd. Overall, the influence extent of the anthropogenic emissions decreased in the order of mine (3 km) dyeing mill (2 km) industrial hub (2 km) fluorescent factory (1.5 km) road (0.5 km) Although algorithm still needs to improved, the PCA MLRD model has the potential to become a useful tool for heavy metal source apportionment in soil.