Manganese sulfide-sulfur and limestone autotrophic denitrification system for deep and efficient nitrate removal: Feasibility, performance and mechanism.

Despite the great potential of sulfur-based autotrophic denitrification, an improvement in nitrate removal rate is still needed. This study used the desulfurized products of Mn ore to develop the MnS-S0-limestone autotrophic denitrification system (MSLAD). The feasibility of MSLAD for denitrification was explored and the possible mechanism was proposed. The nitrate (100 mg/L) was almost removed within 24 h in batch experiment in MSLAD. Also, an average TN removal of 98 % (472.0 mg/L/d) at hydraulic retention time of 1.5 h in column experiment (30 mg/L) was achieved. MnS and S0 could act as coupled electron donors and show synergistic effects for nitrate removal. γ-MnS with smaller particle size and lower crystallinity was more readily utilized by the bacterium and had higher nitrate removal efficiency than that of α-MnS. Thiobacillus and Sulfurimonas were the core functional bacterium in denitrification. Therefore, MnS-S0-limestone bio-denitrification provides an efficient alternative method for nitrate removal in wastewater.

The pH-sensitive transformation of birnessite and its effect on the fate of norfloxacin.

Birnessite plays a crucial role in regulating the fate of contaminants in soil, which is affected by the crystal structure of birnessite. In this study, the transformation of triclinic birnessite to hexagonal birnessite was examined at various pH values, and their reactivity towards norfloxacin was investigated. The findings indicate that the conversion from triclinic birnessite to hexagonal birnessite occurs under pH conditions lower than 7. The lower of the solution pH where the birnessite formed, the higher the surface reactivity. Throughout the transformation process, the migration of Mn3+ and the increased interlayer protons generated more reactive oxygen species, which enhanced the surface reactivity towards norfloxacin. Specifically, at a conversion pH of 1, the norfloxacin removal rate significantly increases from 14% to 97% compared to triclinic birnessite. The mechanism of norfloxacin removal by triclinic and hexagonal birnessite is illustrated. These findings provide valuable insights into the dynamic transformation of birnessites in aqueous environments with varying pH values and their impact on norfloxacin removal.

The synergistic activation of peroxymonosulfate for the degradation of Acid Scarlet GR by palygorskite/MnO2/Fe3O4 nanocomposites.

A heterogeneous Fenton-like system comprising palygorskite/MnO2/Fe3O4 (PMM) as a superior, low-cost, and eco-friendly ternary catalyst for the activation of peroxymonosulfate (PMS) was investigated with regard to its ability to degrade Acid Scarlet GR in an aqueous solution. Under the optimum catalytic oxidation conditions of 1 g L-1 PMM, 0.7 g L-1 PMS, and an initial pH value of 5, 200 mg L-1 Acid Scarlet GR was completely degraded within 300 min. PMM exhibited outstanding magnetic recovery ability and reusability after nine cycles with a degradation efficiency of up to 95.4%. The PMM catalyst had a broad working pH range. Singlet oxygen 1O2 was considered to play the principal role in the degradation of Acid Scarlet GR in the PMM/PMS system. The synergistic effect between MnO2, Fe3O4, and PG substantially accelerated the catalytic activity of PMM, and MnO2 was identified to be the primary active site. These findings indicate that PMM is a nanocatalyst that can efficiently activate PMS for the treatment of dye-containing wastewater.

Phosphate adsorption kinetics and equilibria on natural iron and manganese oxide composites.

Although it is well known that phosphate retention in soils and sediments is strongly influenced by binding to secondary iron oxides, there have been relatively few studies examining its adsorption/desorption behavior on multicomponent particles of realistic natural complexity. In this study, natural Mn-rich limonite (LM), was used to prepare naturally complex Fe- and Mn-oxide composite materials to examine phosphate adsorption/desorption. To clarify the role of the Mn-oxides, results for the LM sample were compared to those for an acid treated version (LAT), in which the acid-extractable Mn-oxide fraction has been selectively eliminated while leaving the Fe-oxide fraction intact. The saturated adsorption capacity on LAT was almost double that on LM, suggesting that phosphate adsorption to the iron oxides is strongly occluded by the Mn-oxide fraction. This result is reinforced by the comparing the pH dependence and fits to adsorption isotherms, and by desorption experiments and STEM-EDS mapping showing that phosphate loading on Mn-oxides was limited. Hence, although the collective results confirm that phosphate uptake and strong binding is selectively controlled by the Fe-oxide fraction, our study reveals that the Mn-oxide fraction strongly interferes with this process. Therefore, phosphate uptake behavior on metal oxides cannot be predicted solely on the basis of the Fe-oxide fraction present, but instead must take into account the deleterious impacts of other intimately associated phases. For co-diagenetic Fe/Mn-oxide composites in particular, Mn-oxides appear to severely limit phosphate uptake on the Fe-oxide fraction, either by hindering access to binding sites on the Fe-oxide or by lowering their affinity for P.

Ultrathin MnO2-Coated FeOOH Catalyst for Indoor Formaldehyde Oxidation at Ambient Temperature: New Insight into Surface Reactive Oxygen Species and In-Field Testing in an Air Cleaner.

Herein, we tailored a series of ultrathin MnO2 nanolayers coated on the surface of commercial goethite (α-FeOOH) by a facile in situ chemical precipitation method. α-FeOOH inhibited the MnO2 crystal growth via the incorporation of K+ ions between MnO2 and α-FeOOH interfaces during the synthesis process. The hybrid design of MnO2 with an ultrathin nanolayer structure could reduce the electron transfer resistance and bring abundant oxygen vacancies, accelerating the activation of molecular O2 to generate more oxygen-free radical species and favoring the thermodynamic HCHO oxidation. The ROS quenching in gas/aqueous systems and DRIFTS results demonstrated that •O2- was responsible for HCHO oxidization, which assisted the preliminary intermediate dioxymethylene dehydrogenation into formate species. The 25%MnO2@FeOOH(25wt% of MnO2) catalyst was subsequently loaded into the filter substrates of a commercial air cleaner and tested in an indoor room with actual application conditions. As a result, the composite filter could eliminate different initial concentrations of HCHO (150-450 ppb) to the WHO guideline value (≈81 ppb) within 60 min. Furthermore, the 25%MnO2@FeOOH sample was also effective against the representative bacteria and mold in indoor air. This study provides new insight into the role of the chemisorbed ROS for HCHO oxidation at ambient temperature.

Ce(SO4)2/α-Fe2O3 selective catalytic reduction of NOx with NH3: preparation, characterization, and performance.

To achieve a low-cost, high-activity denitrification catalyst with excellent water and sulfur resistance, goethite and Ce(SO4)2·4H2O were used to prepare Ce(SO4)2/α-Fe2O3 composite catalyst by the impregnation way and investigated the effect of Ce(SO4)2 on the properties of goethite. Ce(SO4)2/α-Fe2O3 with various preparation conditions for denitration was systematically discussed, and its structure and properties were characterized by XRD, BET, TEM, XPS, H2-TPR, and NH3-TPD methods. The results showed that Ce(SO4)2/α-Fe2O3 over the Ce/Fe molar ratio of 0.02 and calcination temperature of 350 ℃ had excellent catalytic activity, resistance to sulfur, and water properties and stability. When NOx initial concentration was 500 ppm, gas hourly space velocity was 36,000 h-1 and its reaction temperature was 300 ℃; the NOx conversion efficiency was maintained at over 95% along with 300 ppm SO2 and nearly 100% couple with 10% H2O. Its superior performance was mainly attributed to the enhancement of the surface adsorbed oxygen and acidity of α-Fe2O3 by cerium sulfate. The multiple advantages of Ce0.02/α-Fe2O3(350) made it feasible for practical engineering application.

Utilization of methylene blue-adsorbed halloysite after carbonization to activate peroxymonosulfate degrading phenol: Performance and mechanism.

In this study, a new low-cost carbon-based material was prepared via the carbonization of methylene blue adsorbed halloysite (CMH) at different temperatures in a nitrogen atmosphere, which was named CMH-T (T-Temperature). The performance of CMH-T was explored and the effects of initial pH values, catalyst dosage, phenol (PE) concentrations, peroxymonosulfate (PMS) concentrations, and water background compounds on PE degradation were investigated systematically. The results indicated that CMH800 exhibited the best performance to activate PMS for degrading PE. Specifically, 92% PE was degraded within 30 min with a constant rate (kobs) of 0.1186 min-1 in the CMH800/PMS system. Furthermore, CMH800 was efficient over a wide pH range (pH 3-9) and showed a slight inhibition to inorganic anions. Quenching experiments, electron spin resonance (ESR) analysis, and electrochemical analysis confirmed that PE was degraded through non-radical pathways dominated by single oxygen (1O2) and mediated electron transfer processes in the CMH800/PMS system. In addition, the predicted toxicity of intermediates through ECOSAR software based on QSAR (Quantitative Structure - Activity Relationship) model indicated that most of the intermediates had a low risk to water environment. Therefore, the CMH800 has a good potential for wastewater treatment applications.

The synergistic effect of calcite and Cu2+ on the degradation of sulfadiazine via PDS activation: A role of Cu(â ¢).

A system of Cu2+/calcite/PDS was constructed to degrade sulfadiazine (SDZ). Different from the traditional Cu-mediated activation, a low concentration of Cu2+ that met drinking water standards (≤ 1 mg/L) transformed into Cu(Ⅱ) solid in the presence of calcite, and then enhanced the degradation of SDZ via PDS activation over a pH range from 3 to 9. According to scavenger and chemical probe experiments, Cu(Ⅲ), rather than radicals (hydroxyl radicals and sulfate radicals) and singlet oxygen, was the predominant reactive species, which was responsible for the degradation of SDZ. Based on the results of XRD, ATR-FTIR, and CV curves et al., CuCO3 was the main complex with high reactivity for PDS activation to form Cu(Ⅲ). Moreover, detailed degradation pathways of sulfadiazine were proposed according to the UPLC-ESI-MS/MS and their toxicity was predicted by ECOSAR. Besides, the real water matrix would not seriously affect the degradation of SDZ in the Cu2+/calcite/PDS system. In summary, this study reveals a new insight into the synergistic effect of Cu2+ and calcite on the SDZ degradation, and promotes an understanding of the environmental benefits of natural calcite.

H2O2 activation over Co substitution in Fe1-xS for tetracycline degradation: Effect of Co substitution.

In this work, the effect of Co substitution in the Fe1-xS (CSP) on the activation of H2O2 to degrade tetracycline (TC) is investigated. A series of CSP samples with different Co content are synthesized via a high-temperature sulfidation method and characterized by XRD, XPS, SEM, and electrochemical analysis. The result showed that low Co content (≤1%) promotes the catalytic activity of Fe1-xS, while excessive Co (1%﹤x ≤ 3%) inhibits its catalytic activity. The investigation of Behnajady-Modirshahla-Ghanbery kinetic model (BMG) showed that the maximum initial degradation rate of TC over 1.0% CSP/H2O2 was 1.6 times than that of in CSP/H2O2 system. The Box-Behnken with Response Surface Methodology was employed to verify optimum condition for TC degradation. The quenching experiments and ESR determined that ·OH, ·O2- and 1O2 were involved in TC degradation with the treatment of 1.0% CSP/H2O2 system. Electrochemical analysis, ·OH quantification, and metal ion concentrations measure reveal that Co substitution accelerates electron transfer efficiency and Fe2+ regeneration. Furthermore, nine intermediates are identified and the possible degradation pathway of TC is proposed. The unique effect of Co provides novel insight and efficient strategies for improving the reactivity of iron sulfide.

The removal performance and mechanisms of tetracycline over Mn-rich limonite.

Naturally occurring Mn-rich limonite mainly composed of goethite and manganese oxides was used to remove tetracycline (TC) from the aqueous solution. The effects of dosage, initial solution pH, temperature, and coexisting anions on TC removal were investigated. Results showed that 95% of TC (30.0 mg·L-1) was removed in a wide pH range of 3.0-9.0 by limonite with high specific surface area (145.0 m2·g-1) and mesoporous structure. The presence of Cl-, NO3-, and SO42- in the studied concentration range did not influence TC removal efficiency significantly, while PO43- inhibited the adsorption of TC over limonite due to the competition with TC for active sites. Integrated with the FT-IR analysis, electrostatic interaction and complexation were proved to be the adsorption mechanisms of TC by limonite. The quenching experiments and ESR analysis revealed that singlet oxygen (1O2) also was involved in TC degradation. In addition, limonite displayed an efficient recycling performance and stability after four cycles. This study revealed that the Mn-rich limonite was a promising adsorbent for TC removal from aqueous solutions and promoted the application of natural mineral material in the environmental field.

Decomposition of gaseous chlorobenzene using a DBD combined CuO/α-Fe2O3 catalysis system.

Copper oxide and hematite (CuO/α-Fe2O3) composite catalysts were prepared by using goethite as precursor adopted impregnation way and applied to the dielectric barrier discharge (DBD) catalytic decomposition of gaseous chlorobenzene. The CuO/α-Fe2O3 composite was characterised by X-ray diffraction, Brunauer-Emmett-Teller method, scanning electron microscopy and X-ray photoelectron spectrometer technique. The decomposition efficiency and energy yield of gaseous chlorobenzene in DBD catalysis system were studied by a function of gas flow rate, initial concentration and input voltage. The results showed that the CuO/α-Fe2O3 composite catalyst exhibited remarkable performance on chlorobenzene decomposition when the molar ratio was 0.4 and calcination temperature was 450°C. When the chlorobenzene initial concentration was 230 mg m-3, the chlorobenzene decomposition efficiency and mineralisation rate on the DBD catalysis system reached 73.33% and 63.37%, respectively, its decomposition and mineralisation efficiency were enhanced about 20.5% and 16.61%, respectively, compared with the bare DBD system, and it also benefited to significantly reduce the ozone and NO2 by-products. The possible pathway of chlorobenzene decomposition in the DBD catalytic hybrid system was proposed based on the products analysis.

Biodegradable microplastics (BMPs): a new cause for concern?

With the increasingly serious pollution of plastics, biodegradable plastics (BDPs) have attracted attention as a new material that can replace conventional plastics in certain applications. The global production of BDPs also gradually increases in recent years. However, unfortunately, with the application of BDPs, some potential problems are gradually exposed. The biodegradability of BDPs needs suitable conditions, which is difficult for the natural environment to reach the necessary conditions. If the degradation conditions are not met, BDPs and conventional plastics are basically the same in terms of the longevity. The biodegradable microplastics (BMPs) can also be formed by BDPs entering the environment. Up to now, the research on the degradation and application of BDPs is relatively common. The environmental and ecological effects of the BMPs, the adsorption and release of toxic substances, and the role of BMPs as vectors of microorganisms, epiphytes, and plants still need to be studied. This paper focuses on the formation mechanism and the environmental behavior of BMPs. The role of BMPs as multiple stronger vectors of microorganisms and pollutants compared to conventional microplastics is also discussed. Systematic research on environmental pollution and ecotoxicology of BMPs should be carried out as soon as possible.

Degradation of norfloxacin by calcite activating peroxymonosulfate: Performance and mechanism.

In this study, calcite was investigated as an activator for the norfloxacin (NOR) degradation by peroxymonosulfate (PMS). Under optimum conditions, the NOR removal percentage was 99.7% within 60 min, and the pseudo-first-order kinetics effectively described the two-stage oxidation process. The NOR removal percentage improved from 10.4% to 91.5% and the reaction rate constant elevated from 0.0010 to 0.1217 min-1 when 0.5 g/L calcite was added compared to that without calcite addition. Furthermore, the results of radical scavenger and electron spin resonance trapping indicated that the favorable alkaline environment and a proper level of carbonate in the Calcite/PMS system facilitated the activation of PMS to generate 1O2 for rapid NOR degradation. Compared with NaOH, calcite was able to maintain the pH (8-9) of the reaction system stable. Besides, the content of anions with buffering capacity and organic matter in the water matrix influenced the removal percentage of NOR. Seven intermediates were identified and the NOR degradation pathways were suggested. The findings of this research provided an environmentally friendly activator for remediation of organic wastewater and deepened the understanding of the interaction between calcium carbonate and PMS.

The pH-dependent degradation of sulfadiazine using natural siderite activating PDS: The role of singlet oxygen.

Occurring naturally siderite (FeCO3) was used as the heterogeneous catalyst to activate peroxodisulfate (PDS) for the degradation of sulfadiazine under different initial pH values. The findings of this system exhibited various ROS (e.g. 1O2, SO4- and OH) present during a wide range of pH values. Among them, 1O2 could significantly facilitate the initial degradation rate, and the increased pH enhanced the role of 1O2. The factors including initial pH values, siderite dosage, PDS concentration, initial contaminants concentration, and water matrix were discussed. The role of each ROS was investigated through quenching test and electron paramagnetic resonance (EPR). Furthermore, the comprehensive degradation process was proposed based on the LC-MS results. And the cycle test demonstrates the reusability of siderite at a pH of 3. Accordingly, this study is of great significance for understanding the degradation of such sulfonamide pollutants in the siderite/PDS system.

Effect of iron minerals during coaling on the transformation of NO in the presence of NH3: Take pyrite as an example.

Pyrite, a naturally occurring mineral, can be found extensively in coal. The change in the pyrite structure that occurs during coaling process, the ability of the pyrite-derived α-Fe2O3 to convert NO in the presence of NH3 before catalyst bed and the kinetic study were investigated in this work. The pyrite-derived α-Fe2O3 was obtained by calcining at 500, 600, 700, 800 °C and was characterized by the X-ray diffraction (XRD), N2 physisorption, the X-ray photoelectron spectrometer (XPS), the scanning electron microscope (SEM), UV-visible near-infrared spectroscopy (UV-vis DRS), the temperature-programmed desorption of ammonia (NH3-TPD) and the in situ diffuse reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS). The results indicated that the α-Fe2O3 derived from natural pyrite exhibited an affirmative effect on NO conversion in the presence of NH3 at reaction temperatures of 200-450 °C, particularly at 350 °C, the pyrite-derived α-Fe2O3 displayed the best efficiency for the NO conversion. In addition, the formed sulfate derived from the oxidation of pyrite enhanced the NO conversion at the temperature of 300-450 °C, while hinder the NO conversion at 200-275 °C. The in-situ DRIFTS and kinetic studies demonstrated that both the Eley-Rideal and Langmuir-Hinshelwood mechanism contributed to the selective catalytic reduction (SCR) of NO when the reaction temperature was over 200 °C, while selective catalytic oxidization (CO) happened over 300 °C. This study favored the understanding of the NO behavior in flue gas pipeline after sprawling NH3 and the mechanism of NO conversion before the catalyst bed.

The positive effect of siderite-derived α-Fe2O3 during coaling on the NO behavior in the presence of NH3.

Siderite is a naturally occurring mineral that can be found extensively in coal. The structural evolution of siderite in the process of coaling and its performance in the transformation of NO in the presence of NH3 were investigated in this work. In addition, the effects of the coexisting component, including vapor, SO2, and the alkali metal K, were also discussed. Heat treatment was performed at 450, 500, 550, 600, and 700 °C to obtain siderite-derived α-Fe2O3, which was then evaluated in de-NOx via the selective catalytic reduction (SCR) of NO with NH3 in a fixed bed. The X-ray diffraction (XRD), the X-ray fluorescence spectrometer (XRF), N2 adsorption-desorption (BET), the X-ray photoelectron spectrometer (XPS), the scanning electron microscope (SEM), and the transmission electron microscope (TEM) were used to investigate the variations in the morphology and structure of the thermally treated siderite. The results showed that siderite was gradually oxidized and decomposed into α-Fe2O3 with a nanoporous structure and large surface area of 27.27 m2 g-1 after calcination under an air atmosphere. The α-Fe2O3 derived from siderite at 500 °C (H500) exhibited an excellent SCR performance, where the NO conversion rate was great than 90% between 250 and 300 °C due to the pore structure and high specific surface area, additional adsorbed oxygen states, abundant oligomeric Fe oxide clusters, and large amount of acid sites. Regardless of the vapor content, SO2 concentration, and reaction temperature, the α-Fe2O3 derived from siderite at 500 °C (H500) still favored the conversion of NO. When the reaction temperature was lower than 350 °C, H500 favored the conversion of NO even in the presence of an alkali metal (K). The experimental data demonstrated the positive effect of siderite-derived α-Fe2O3 in SCR technology and provided insight into NO behavior in coaling flue gas after NH3 injection.

A novel discovery of a heterogeneous Fenton-like system based on natural siderite: A wide range of pH values from 3 to 9.

Natural iron-bearing minerals have been proven to be effective for activating H2O2 to produce OH, which can be used to degrade organic pollutants. In this study, the performance of siderite to degrade sodium sulfadiazine via catalytic H2O2 degradation was investigated at different solution pH values from 3 to 9. An interesting discovery was made: the performance of the siderite-H2O2 system was excellent under acidic, neutral, and even alkaline conditions. The influence of various factors (e.g. initial concentration, anions, natural organic matters, etc.) on the system under different pH conditions was investigated, which confirmed that siderite exhibited an excellent catalytic performance. By combining EPR characterization with scavenger research, it was proposed that dissolved iron (Fe2+) mainly initiated the homogenous Fenton reaction to degrade pollutants under acidic conditions, while structural Fe2+ species present in siderite triggered Fenton-like reactions under neutral or even alkaline conditions. From the SEM and XPS characterizations, oxidation and dissolution of Fe2+ on the surface were also observed, confirming our inference concerning the different reaction mechanisms. The experimental findings show that this siderite-H2O2 system can be used in solutions with pH values from 3 to 9 and that siderite plays a positive role in soil and groundwater remediation when H2O2 is used as an oxidant.

Performance of selective catalytic reduction of NO with NH3 over natural manganese ore catalysts at low temperature.

Natural manganese ore catalysts for selective catalytic reduction (SCR) of NO with NH3 at low temperature in the presence and absence of SO2 and H2O were systematically investigated. The physical and chemical properties of catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller (BET) specific surface area, NH3 temperature-programmed desorption (NH3-TPD) and NO-TPD methods. The results showed that natural manganese ore from Qingyang of Anhui Province had a good low-temperature activity and N2 selectivity, and it could be a novel catalyst in terms of stability, good efficiency, good reusability and lower cost. The NO conversion exceeded 85% between 150°C and 300°C when the initial NO concentration was 1000 ppm. The activity was suppressed by adding H2O (10%) or SO2 (100 or 200 ppm), respectively, and its activity could recover while the SO2 supply is cut off. The simultaneous addition of H2O and SO2 led to the increase of about 100% in SCR activity than bare addition of SO2. The formation of the amorphous MnOx, high concentration of lattice oxygen and surface-adsorbed oxygen groups and a lot of reducible species as well as adsorption of the reactants brought about excellent SCR performance and exhibited good SO2 and H2O resistance.

The Adsorption of Cd(II) on Manganese Oxide Investigated by Batch and Modeling Techniques.

Manganese (Mn) oxide is a ubiquitous metal oxide in sub-environments. The adsorption of Cd(II) on Mn oxide as function of adsorption time, pH, ionic strength, temperature, and initial Cd(II) concentration was investigated by batch techniques. The adsorption kinetics showed that the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by pseudo-second-order kinetic model with high correlation coefficients (R² > 0.999). The adsorption of Cd(II) on Mn oxide significantly decreased with increasing ionic strength at pH < 5.0, whereas Cd(II) adsorption was independent of ionic strength at pH > 6.0, which indicated that outer-sphere and inner-sphere surface complexation dominated the adsorption of Cd(II) on Mn oxide at pH < 5.0 and pH > 6.0, respectively. The maximum adsorption capacity of Mn oxide for Cd(II) calculated from Langmuir model was 104.17 mg/g at pH 6.0 and 298 K. The thermodynamic parameters showed that the adsorption of Cd(II) on Mn oxide was an endothermic and spontaneous process. According to the results of surface complexation modeling, the adsorption of Cd(II) on Mn oxide can be satisfactorily simulated by ion exchange sites (X2Cd) at low pH and inner-sphere surface complexation sites (SOCd⁺ and (SO)2CdOH- species) at high pH conditions. The finding presented herein plays an important role in understanding the fate and transport of heavy metals at the water-mineral interface.

[Preparation of Magnetic Biomass Carbon by Thermal Decomposition of Siderite Driven by Wheat Straw and Its Adsorption on Cadmium].

C-Fe3O4 composite material [magnetic biomass char (MBC)] was prepared by pyrolysis of a mixture of wheat straw and siderite at 500℃. The MBC was characterized by XRF, FTIR, XRD, SEM, XPS, and a magnetic susceptibility device. The effect of contact time, pH value, initial Cd2+ concentration, and ionic strength on the adsorption capacity of the MBC to Cd2+ was investigated. The results showed that the BET surface areas of the MBC and biomass char (BC) were 23.38 m2·g-1 and 7.20 m2·g-1, respectively, total pore volumes were 1.04×10-1 cm3·g-1 and 2.23×10-2 cm3·g-1, and average pore diameters were 17.74 nm and 12.38 nm. The magnetic susceptibility of the MBC was 42900×10-8 m3·kg-1. FTIR showed that phenolic hydroxyl and carboxyl functional groups bound metal ions on the surface of the MBC and BC. The kinetic data of the MBC were described well by the pseudo-second-order model. Isothermal adsorption of Cd2+ by MBC and BC was fitted well by the Freundlich equation. The adsorption velocity increased with an increase of pH in the region 3-6 and then stabilized in the region 6-9. The adsorption capacity of Cd2+ decreased slightly when ionic strength increased from 1 mmol·L-1 to 100 mmol·L-1, whereas the desorption rate increased from 0.51% to 8.5%. The adsorption properties and characterization results illustrated that the removal mechanism of Cd2+ likely was through adsorption and ion exchange on the surface of the MBC with a high amount of functional groups. In addition, magnetic adsorbents offered a significant advantage compared to other adsorbents in the aspect of separation from aqueous solution.