Fe-modified Biochar Research Articles

Adsorption of Cr(VI) from wastewater by iron-modified coconut shell biochar

This study is aimed to investigate the effect of raw and Fe-modified coconut shell biochar on the adsorption of Cr(VI) in the wastewater. Fe-modified biochar was obtained from the impregnation with FeNO3 solutions and the surface functional groups of two biochars were examined by infrared spectrometer.The result showed that the Fe-modified biochar had lower abundance of the surface functional groups than that of raw biochar, and had the group of Fe-O.The removal rate of Cr(VI) increased by 94.89% compared with the raw biochar because of existing of the group of Fe-O . The removal rate of Cr(VI) by modified biochar could reach more than 99.0% when the concentration of Cr(VI) was 12μg/ mL, pH 4.0, adsorbent dosage was 0.2g and adsorption time was 2h.

Fe-Modified Common Reed Biochar Reduced Cadmium (Cd) Mobility and Enhanced Microbial Activity in a Contaminated Calcareous Soil

The immobilization of soil cadmium (Cd) by biochar and modified biochar is an eco-friendly and cost-effective strategy. In the current study, the effect of raw biochar (BC) and iron-modified biochar (Fe-BC) derived from common reed on the fractionation and mobility of Cd was evaluated, as was its effect on soil microbial activity in contaminated calcareous soil. Treatments involved a combination of two factors: type of biochar (CK: Control, BC, and Fe-BC) and soil Cd concentration (0, 15, and 30 mg kg−1). Treatments were applied to the soil and incubated for 90 days. The application of both biochars increased soil pH and soil organic carbon content (16.6–48.0%), microbial biomass carbon (40.5–75.1%), basal respiration (16.6–48.0%), substrate-induced respiration (12.4–41.9), and dehydrogenase activity (25.5–102.1%), while it reduced diethylene-triamine pentaacetic acid (DTPA)-extractable Cd (22.1–39.5%). The addition biochars, particularly Fe-BC, prominently decreased the concentration of exchangeable and carbonate fractions and increased the concentration of Fe-MnOx, as well as the organic and residual fractions of Cd in the soil. Moreover, relative to the control treatment, the incorporation of raw and Fe-modified biochar into 30 mg kg−1 Cd-spiked soil significantly decreased the Cd mobility factor (MF) value by 14.5 and 21.8%, respectively. Fe-modified biochar had a more significant impact than raw biochar on the immobilization of Cd in the soil, and its improved soil microbial activity to a greater extent. Overall, the findings indicate that Fe-modified biochar derived from common reed can immobilize Cd and improve soil microbial attributes in contaminated calcareous soil. Therefore, it can be used as an eco-friendly amendment for restoring Cd-contaminated calcareous soil.

Iron-modified biochar and water management regime-induced changes in plant growth, enzyme activities, and phytoavailability of arsenic, cadmium and lead in a paddy soil

The aim of this study was to evaluate the effect of raw (RawBC) and iron (Fe)-modified biochar (FeBC) derived from Platanus orientalis Linn branches on the plant growth, enzyme activity, and bioavailability and uptake of As, Cd, and Pb by rice in a paddy soil with continuously flooded (CF) or alternately wet and dry (AWD) irrigation in a pot experiment. Application of RawBC (3%, w/w) significantly increased soil pH, while FeBC decreased it. The FeBC was more effective in reducing As and Pb bioavailability, particularly under the AWD water regime, while RawBC was more conducive in reducing Cd bioavailability under the CF water regime. The FeBC decreased As concentration, but increased concentrations of Cd and Pb in the straw and brown rice, as compared to the untreated soil. Soil catalase and urease activities were enhanced by RawBC, but decreased by FeBC treatment. The FeBC increased the grain yield by 60% and 32% in CF and AWD treatments, respectively. The FeBC can be recommended for immobilization of As in paddy soils, but a potential human health risk from Cd and Pb in FeBC-treated soils should be considered due to increased uptake and translocation of the metals to brown rice.

Role of passivators for Cd alleviation in rice-water spinach intercropping system

Soil pollution with cadmium (Cd) has posed a threat to our food safety. And rice consumption is the main source of Cd intake in China. Rice intercropping with water spinach is an efficient way for crop production and phytoremediation in Cd-contaminated soil. However, few people work on the Cd remediation by a combination of the passivation and intercropping. In this study, two passivators (the Si–Ca–Mg ameliorant and the Fe-modified biochar with microbial inoculants) were used in the monoculture and intercropping systems to evaluate the potential of co-effect of passivators and cropping systems on the plant growth and Cd phytoremediation. Results showed that the highest rice biomass and rice yield were presented in the intercropping system with the passivator additions, however, relatively lower biomass was showed in water spinach due to the competition with rice. And more Cd accumulated in water spinach while lower Cd in that of different rice parts. The intercropping system with the addition of the Si–Ca–Mg ameliorant and the microbial Fe-modified biochar significantly reduced the Cd contents in brown rice by 58.86% and 63.83%, while notably enhanced the Cd accumulation of water spinach by 32.0% and 22.0%, compared with the monoculture without passivation, respectively. This probably due to the increased pH, the lowered Cd availability in soil, and the reduced TF and BCF values in rice plants with passivator applications. Collectively, this study indicated that rice-water spinach intercropping, especially with the passivator additions, may function as an effective way for Cd remediation and guarantee rice grain safety.

Fe-modified biochar enhances microbial nitrogen removal capability of constructed wetland

To improve the nitrogen removal capability of constructed wetlands, the biochar, produced from bamboo, activated with HCl and coated with Fe (FeCl3·6H2O), and then was added as a substrate into the systems. Three horizontal subsurface flow constructed wetlands (HSCWs) was established to treat the low C/N tailwater from the wastewater treatment plant: C-HSCW (quartz sand + soil), B-HSCW (quartz sand + soil + unmodified biochar), and FeB-HSCW (quartz sand + soil + Fe-modified biochar). Under different combinations of hydraulic retention time and nitrogen loading, the FeB-HSCW revealed extremely effective nitrogen removal, compared to the C-HSCW and B-HSCW. The highest removal efficiencies of NO3−-N (95.30%), TN (86.68%), NH4+-N (86.33%), NO2−-N (79.35%) and COD (63.36%) were obtained in FeB-HSCW with the hydraulic retention time of 96 h. and low influent nitrogen loading (C/N of 2.5). Nitrogen mass balance analysis showed that microbial processes played the most important role of nitrogen removal in HSCWs and the Fe-modified biochar significantly enhanced the microbial nitrogen removal. A total of 128.40 g nitrogen was removed by microorganisms in FeB-HSCW (average removal rate of 2.52 g N/(m3·d1)), much higher than that in other two HSCWs. The contributions of microorganisms, substrate storage and plant uptake on the total amount of nitrogen removal in the FeB-HSCW was 92.69%, 2.97% and 4.34%, respectively. Moreover, FeB significantly increased the abundances of genes involved in nitrogen removal. The copy numbers of bacterial 16S rRNA and amx, as well as of genes nirS, nirK, nosZ-I, nosZ-II, and hzsA were 1.3- to 27.8-fold higher in the FeB-HSCW than that in the other two HSCWs. Thus, Fe-modified biochar provides a feasible and effective amendment for constructed wetlands to improve the nitrogen removal, particularly nitrate-N, for low C/N wastewaters by enhancing the microbial nitrogen removal capacity (mainly of the denitrification).

Mechanistic investigation of mercury removal by unmodified and Fe-modified biochars based on synchrotron-based methods

Improved surface characteristics and incorporated Fe, S, and Cl species are reported in Fe-modified biochar, which makes it a prospective material for Hg(II) removal. In this study, aqueous Hg(II) was removed from solution by unmodified, FeCl3-modified, and FeSO4-modified biochars pyrolyzed at 300, 600, or 900 °C. Higher pyrolytic temperature resulted in higher removal efficiency, with the biochars pyrolyzed at 900 °C removing >96% of Hg(II). Fe-modification enhanced Hg(II) removal for biochars pyrolyzed at 600 °C (from 88% to >95%) or 900 °C (from 96% to 99%). Based on synchronous extended X-ray absorption fine structure (EXAFS) analysis, Hg coordinated to S in modified and unmodified biochars pyrolyzed at 900 °C, where thiol was reported, and in FeSO4-modified biochars pyrolyzed at 600 or 900 °C, where sulfide was recognized; in other biochars, Hg bound to O or Cl. Additionally, confocal micro-X-ray fluorescence imaging (CMXRFI) demonstrated Hg was distributed in agreement with S in biochars where HgS was formed; otherwise, Hg distribution was influenced by Hg species in solution and the pore characteristics of the biochar. This investigation provides information on the effectiveness and mechanisms of Hg removal that is critical for evaluating biochar applications and optimizing modification methods in groundwater remediation.

As(III) and As(V) removal mechanisms by Fe-modified biochar characterized using synchrotron-based X-ray absorption spectroscopy and confocal micro-X-ray fluorescence imaging

Batch experiments followed by solid-phase analyses were conducted to explore As(III) and As(V) removal mechanisms by Fe-modified biochars (FeBC) pyrolyzed at different temperatures (300, 600, and 900 °C). Arsenic removal by FeBC, best described by pseudo-second order kinetic and Langmuir isotherm models, increased from 73.8 to 99.9% for As(III) and 86.8 to 99.9% for As(V) as the pyrolysis temperature increased. The addition of calcite enhanced the removal efficiency (all > 99%). Confocal micro-X-ray fluorescence imaging (CMXRFI) analyses indicated As co-located with Fe and diffused deeper into the particles as the pyrolysis temperature increased. For As(III)-spiked systems, X-ray absorption near-edge structure (XANES) data indicated 20.2 to 81.5% of As(III) was oxidized to As(V) as the pyrolysis temperature increased; an increase of oxidation efficiency was observed after adding calcite. For As(V)-spiked systems, no As(V) reduction was observed. Overall, As(III/V) removal using FeBC was affected by the spatial distribution and species of As.

Simultaneous Immobilization of Soil Cd(II) and As(V) by Fe-Modified Biochar.

Remediation of soil heavy metal by biochar has been extensively studied. However, few studies focused on the role of biochar on the co-immobilization of cadmium (Cd(II)) and arsenate (As(V)) and related soil nutrient availability. Remediation tests were conducted with three types of pristine and ferric trichloride (FeCl3) modified biochar (rice, wheat, and corn straw biochar) in Cd-As co-contaminated soil, with application rates of 1, 5, and 10% (w/w) and the incubation of 1, 7, 10, and 15 days. Using TCLP (Toxicity Characteristic Leaching Procedure) method, 10% of FeCl3 modified corn-straw derived biochar (FCB) had the highest immobilization efficiency of Cd(II) (63.21%) and As(V) (95.10%) after 10 days of the incubation. Iron-modified biochar immobilized higher fractions of water-soluble (F1) and surface-absorbed (F2) metal fractions than pristine biochar. For FCB amendment, Cd was mostly presented in the organic matter (OM) and sulfides associated (F4) and residual (F5) fractions (88.52%), as was found in the Fe-Al (oxides and hydroxides) (F3), F4, and F5 fractions (75.87%). FCB amendment increased soil pH values and available iron contents (p < 0.05), while no changes in soil available phosphorus content (p > 0.05). This study showed that FCB application reduces the environmental mobility of metals in Cd-As contaminated soil, while it also increases soil pH and available nutrient mobility, improving soil environmental quality and reducing remediation costs.

Removal of abamectin and conventional pollutants in vertical flow constructed wetlands with Fe-modified biochar.

To improve the ability of constructed wetlands to remove abamectin (ABM) and nutrients, the influence of four different substrates on constructed wetlands was studied. Four vertical up-flow constructed wetlands (UVCWs) were established to treat simulated agricultural wastewater: CW1 (quartz sand + pebbles), CW2 (pebbles + coke), CW3 (Fe-modified biochar + pebbles + coke), and CW4 (unmodified biochar + pebbles + coke). Under different combinations of hydraulic loading and organic loading, CW3 was extremely effective at removing nitrogen compared with CW1, CW2 and CW4. We found that CW3 was the most effective at treating ABM and conventional pollutants. The highest efficiency of removal of abamectin (99%), COD (98%), NH4+–N (65%), and TP (80%) was obtained in CW3. These results were directly verified by microbiological tests and microbial community analysis. The microbial diversity of CW3 and CW4 was significantly higher than those of CW1 and CW2. Fe-modified biochar provides a feasible and effective amendment for constructed wetlands to improve the nitrogen removal for C/N (2.5 : 1–5 : 1) wastewater by the ability of microbes to remove nitrogen. Fe-modified bamboo charcoal can be used in engineering as a new type of green environmental protection constructed wetland filler in the future.

Synthesis of iron modified rice straw biochar toward arsenic from groundwater

The potential of Fe modified biochar (BC) as an alternative, inexpensive adsorbent for removing As(V) from wastewater was investigated. BC was synthesized from the slow pyrolysis of rice straw and then modified with FeCl3. The result from FTIR and SEM-EDX demonstrated that Fe had loaded successfully on the surface of biochar. In comparison to the raw biochar, the Fe modified BC not only had stronger magnetic property but also showed much greater ability to remove As(V) from aqueous solution. The Fe modified BC showed a maximum adsorption with an initial solution pH of 5.0. The adsorption data were better fitted with the Langmuir isotherm and pseudo-second kinetic model. The maximum adsorption capacity (qmax) by the modified BC, based on the Langmuir isotherm, was 26.9 mg g−1. The Fe-modified BC can be an effective, inexpensive, and environmentally sustainable adsorbent to replace typical granular activated carbons (AC) commonly utilized in the treatment of arsenic-contaminated wastewater.

Characteristics and Heavy Metal Adsorption Performance of Sewage Sludge-derived Biochar from Co-pyrolysis with Transition Metals

To enhance the heavy metal cation adsorption capacity of sewage sludge-derived biochar in an aqueous medium with a high concentration of Ca2+, modified biochars were obtained from co-pyrolysis of sewage sludge and transition metal oxides (with a sewage sludge:transition metal mass ratio of 10:1), such as Fe2O3, MnO2, and ZnO. The properties of the modified biochars were characterized, and the Cd2+ adsorption effect of the modified biochars was determined as well. The H/C atom ratios of the modified biochars were all lower than 0.31, indicating that the transition metal oxides catalyzed the decomposition and volatilization of organic matter in sewage sludge. The majority of the added Fe and Mn remained in the modified biochars, and existed as a simple substance and oxide, respectively; while significant loss of Zn occurred. The pores of the modified biochars were mainly mesopores with an average pore size of approximately 3.8 nm, and the specific surface area of the modified biochars was larger than 50 m2·g-1. When the initial Cd2+ concentration was increased from 0 mg·L-1 to approximately 200 mg·L-1, the Cd2+ adsorption capacity of the Fe-modified biochar declined from 43.17 mg·g-1 to 27.88 mg·g-1, which was still higher than that of the unmodified biochar by at least 10 mg·g-1. In aqueous media with a high concentration of Ca2+, the Fe-modified biochar showed better Cd2+ adsorption performance; thus, compared to MnO2 and ZnO, Fe2O3 was the best choice to enhance the heavy metal adsorption performance of the sewage sludge-derived biochar.

Adsorption of phosphorus onto Fe-modified Thalia dealbataderived biochar

How to remove P effectively in eutrophic water is an urgent problem to be solved. In this study, a Fe-modified biochar was prepared by pyrolyzed wetland plant Thalia dealbata. The adsorption of P was investigated by using the prepared biochar (TBC-Fe) as an adsorbent. The effects of contact time, initial P concentration, temperature and initial solution pH on adsorption behavior of P on TBC-Fe were studied. The results showed that P adsorption process on TBC-Fe was controlled by internal and external diffusion of particles, due to the adsorption kinetic was better fitted by Intra-particle diffusion model. The adsorption isotherm on TBC-Fe was well performed by Langmuir model, with a maximum P adsorption capacity of 15.86 mg/g. The best adsorption performance was exhibited at 25°C with the initial pH of 10. Overall, the results indicate a promising option of utilizing Fe-modified biochar derived from wetland plants as an efficient remediation adsorbent for phosphorus in water.

Correction to: Sorption separation of Eu and As from single-component systems by Fe-modified biochar: kinetic and equilibrium study

Unfortunately, the address of Barbora Michalekova-Richveisova is wrong in the published article. The correct address is given below as number 6.

Adsorption of Malachite Green on Fe-modified biochar: influencing factors and process optimization

Adsorption of Malachite Green on Fe-modified biochar: influencing factors and process optimization

Sorption separation of Eu and As from single-component systems by Fe-modified biochar: kinetic and equilibrium study

The utilization of carbonaceous materials in separation processes of radionuclides, heavy metals and metalloids represents a burning issue in environmental and waste management. The main objective of this study was to characterize the effect of chemical modification of corncob-derived biochar by Fe-impregnations on sorption efficiency of Eu and As as a model compounds of cationic lanthanides and anionic metalloids. The biochar sample produced in slow pyrolysis process at 500 °C before (BC) and after (IBC) impregnation process was characterized by elemental, FTIR, SEM-EDX analysis to confirm the effectiveness of Fe-impregnation process. The basic physico-chemical properties showed differences in surface area and pH values of BC- and IBC-derived sorbents. Sorption processes of Eu and As by BC and IBC were characterized as a time- and initial concentration of sorbate-dependent processes. The sorption equilibrium was reached for both sorbates in 24 h of contact time. Batch equilibrium experiments revealed the increased maximum sorption capacities (Qmax) of IBC for As about more than 20 times (Qmax BC 0.11 and Qmax IBC 2.26 mg g−1). Our study confirmed negligible effect of Fe-impregnation on sorption capacity of biochar for Eu (Qmax BC 0.89 and Qmax IBC 0.98 mg g−1). The iron-impregnation of biochar-derived sorbents can be utilized as a valuable treatment method to produce stable and more effective sorption materials for various xenobiotics separation from liquid wastes and aqueous solutions.