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The toxic organic pollutant with high concentration in landfill leachate is increasingly harmful to human health. In order to treat landfill leachate more efficiently, a novel cheap organobentonite (CTMAB-bentonite) was successfully prepared from Na-bentonite modified with cetyltrimethylammonium bromide (CTMAB) as intercalation agent. The CTMAB-bentonite were characterized by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy, and the effects of contact time, CTMAB concentration, temperature and pH on the adsorption performance were investigated. XRD analysis results showed that CTMAB with concentration of 4 mmol/5 g was successfully intercalated into bentonite, and the layer spacing of CTMAB-bentonite increased by 6 Å than larger that before modification. The adsorption experiment results indicated that the best adsorption time is 60 min, pH and temperature have little effect on the adsorption performance. The adsorption process of landfill leachate conforms to the Freundlich and pseudo-second-order kinetic model, which indicated a multimolecular layer and chemical adsorption, respectively. Thermodynamic parameters confirmed that adsorption process was spontaneous and exothermic. Bentonite modified by CTMAB has a satisfactory adsorption effect on leachate and satisfactory adsorption capacity. CTMABbentonite was an excellent adsorbent for removal of landfill leachate which was promising in the field of wastewater treatment. [ABSTRACT FROM AUTHOR]

Lanthanum-modified mesoporous silica (MS-La) with a specific surface area of 386 m2/g was prepared using mesoporous silica and lanthanum(III) as raw materials by co-precipitation method. The composite adsorbent is ideal for the removal of solutions contaminated with phosphate, due to their chemical stability and a strong affinity with phosphate. MS-La could effectively removal of phosphate within the pH range of 3-6. The coexisting anions result manifested that MS-La with excellent selectivity to phosphate was determined by the hydrogen bonding mechanism in competitive anion solutions. The adsorption kinetics was well fitted with the pseudo-second-order kinetic equation, suggesting chemical adsorption. The Langmuir isothermal model could better describe the adsorption isotherm data and the maximum adsorption capacity of 27.98 mg/g. Furthermore, the main mechanism of phosphate adsorption was electrostatic attraction and ligand exchange. Its efficient adsorption capacity ensures a bright prospect for low-concentration phosphate removal. [ABSTRACT FROM AUTHOR]

The sodium functionalized ultrasonic-diatomite (U-D-Na) was used as an adsorbent to remove phosphorus from an aqueous solution. After simple ultrasonic purification, diatomite was functionalized by the cheap NaCl reagent to prepare U-D-Na. The microstructure and properties of U-D-Na were achieved by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy and thermogravimetry/differential scanning calorimetry. The effect on the contact time, the temperature, the dosage of adsorbent, pH and the initial concentration of phosphorus were investigated during the adsorption kinetics and equilibrium studies. The U-D-Na exhibited that the adsorption efficiency reached more than 90% at optimal conditions. Multiple cycles of adsorption and desorption tests showed that the adsorbent performed good renewability. The experimental values were coincidence with the pseudo-second-order kinetic model and the Langmuir isotherm model. Also, thermodynamic parameters such as the ΔG°, ΔH° and ΔS° illustrated that the adsorption process is essentially exothermic and spontaneous. The results indicated that a promising application prospect for water pollution management by U-D-Na [ABSTRACT FROM AUTHOR]

Proper disposal of membrane-concentrated leachate (MCL) is problematic for municipal solid waste incineration (MSWI) plants. Many MSWI plants treat concentrated leachate using multistage processes, among which a pretreatment before advanced oxidation process (AOP) is the most common practice. In this study, four commonly used coagulants were applied to conduct enhanced coagulation pretreatment on a two-stage tight material MCL, which is collected from MSWI plants. Conditions of enhanced coagulation, including coagulant and its dosage (PSAF, 5 g L–1), coagulant aid dosage (PAM, 80 mg L–1), and initial pH (7), were determined through a single factor experiment. After pretreatment, the removal efficiency toward chemical oxygen demand (COD), UV absorption at 254 nm, total nitrogen, color, and turbidity were 80.6%, 89.0%, 97.8%, 17.0%, and 84.8%, respectively. Moreover, dissolved organic matter (DOM) characteristics before and after pretreatment were investigated via spectrum analyses in detail. UV-visible light and three-dimensional fluorescence analysis showed that the MCL was laden with refractory organic matter; concentration of DOM, especially that of humic-like acid, were deeply decreased after pretreatment. While flow field-flow fractionation measurements illustrated DOM molecular weight was just slightly reduced by the enhanced coagulation, and it was challenging for the enhanced coagulation to change the DOM molecular weight distribution. Finally, the results of gas chromatography-mass spectrometry analysis were illustrated that the main types of volatile organic compounds (VOCs) in MCL were chain organic compounds and some aromatic compounds with relatively low molecular weight, and they were easily removed or decomposed through enhanced coagulation. This study provides a theoretical basis for the enhanced coagulation for pretreatment of MCL. [ABSTRACT FROM AUTHOR]

In this work, a new composite material was prepared and used to remove 17a-ethinyl estradiol (EE2). The structure and morphology of multi-walled carbon nanotubes (MWNTS), activated multi-walled carbon nanotubes (A-MWNTS) and nano-iron/multi-wall carbon nanotubes (A-MWNTS/ Fe) were characterized by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The influencing aspects including equilibrium time, A-MWNTS/Fe dosage, pH, initial EE2 concentration, temperature, different materials, and interference factors on the EE2 removal were investigated. The results show that when the time is 20 min, the dosage of A-MWNTS/Fe is 0.015 g, pH is 6-8, the initial concentration of EE2 is 3 mg L-1, and the temperature is within the range of 15°C-25°C, the removal rate of EE2 reach over 99%. Moreover, the adsorption data are in good agreement with the Langmuir isotherm model and the pseudo-second-order kinetic model. EE2 can be removed by A-MWNTS/Fe because of its high practicability and good application prospect, and the removal rate can reach more than 90%. In summary, A-MWNTS/Fe with facile synthesis method, efficient adsorption performance, and excellent reusability shows potential promise for the treatment of wastewater. [ABSTRACT FROM AUTHOR]

Super activated carbon of vetiver root (SAC-VR) was prepared by using potassium hydroxide as an activator. According to the effects of activation time, the mass ratio between KOH and char of vetiver’s root (KOH/C ratio) and activation temperature to iodine adsorption, the preparation of SAC-VR was optimized by response surface methodology (RSM). The performances of SAC-VR were investigated by Brunauer–Emmett–Teller (BET), scanning electron microscopy, Fourier transform infrared, thermogravimetric (TG) and X-ray diffraction (XRD). Three parameters of SAC-VR preparation were optimized as follows: activation time was 40 min, activation temperature 936.7°C, and KOH/C ratio 4.98:1. Under the optimized condition, the iodine number of SAC-VR was 1,702 mg/g. The surface of SAC-VR was uneven and had an extensive pore structure. The maximum specific surface area BET was 2,278.27 m²/g, indicating that a large surface area was formed in the activation process of SAC-VR.TG analysis suggests that char of vetiver’s root pyrolyzed at 500°C (CHAR) has more cellulose, hemicellulose than SAC-VR. XRD pattern shows that the degree of crystallinity of SAC-VR is lower than that of CHAR. Adsorption behaviors of SAC-VR on bisphenol A (BPA) in the solution were studied. SAC-VR had a good absorption effect on BPA (removal efficiency > 90%). The adsorption process was monolayer adsorption and could be described by the pseudo-second-order kinetic model. SAC-VR could be used in sewage treatment with the solution’s pH close to neutral and a novel approach for application of vetiver waste was provided. [ABSTRACT FROM AUTHOR]

Mesoporous potassium phosphotungstate/silicon dioxide photocatalysts (KPW/SiO2) were prepared by the sol-gel method using cetyl trimethyl ammonium bromide (CTAB), tetraethoxysilane (TEOS) as raw materials and prepared insoluble potassium phosphotungstate. The structures of KPW/SiO2 were characterized by using XRD, BET, IR and TG. The photocatalytic activities were evaluated by using the organic pesticide chlorothalonil as a model reactant. The results indicate that the degradation rate reaches 86.04% when the illumination time is 120 min under 100 W mercury lamp, the dosage of KPW/SiO2 is 0.01 g, the concentration of chlorothalonil is 5 mg/L, pH = 5. Mesoporous SiO2 effectively enhanced the photocatalytic activity of KPW (70%). [ABSTRACT FROM AUTHOR]

In this paper, the dynamic and static adsorption performance of phosphate in the water on the zirconium modified zeolite (Cl2OZr/zeolite) was investigated. Batch adsorption experiments were performed to evaluate the adsorption conditions and selectivity. The experimental results agree well with the pseudo second-order kinetic model. The effects of the dynamic adsorption of phosphate on Cl2OZr/zeolite were studied. The results indicate that the breakthrough time is 480 min and the phosphate removal rate reaches 95% under the optimal conditions. The curves of dynamic adsorption could be fitted by the Thomas model. Cl2OZr/zeolite can be reused and applied to the actual waste water treatment. Comparing previous studies on phosphate removal with different adsorbents, we can see that the Cl2OZr/zeolite has the advantages of wide pH range, relatively short adsorption equilibrium time and reusability. [ABSTRACT FROM AUTHOR]

In this paper, the mesoporous silica (denoted as Ms) was modified by cerium and the optimum preparation conditions were investigated for cerium loaded mesoporous silica materials (denoted as Ms-Ce). The Ms-Ce materials for the fluoride removal performance were characterized by using SEM, XRD, FT-IR and TG-DTA. The Ms-Ce had good defluorination performance due to its large surface area and good-dispersive effect. The results show that cerium is successfully loaded onto the surface of the Ms and the structure of Ms did not change during the loading process. The defluorination loading by Ms-Ce can reach 75.54% under the optimum conditions (nNaHCO3/nCe = 3.0, nCe/nSi = 0.08 and 90°C drying temperature). The adsorption performance and capacities of Ms-Ce were investigated through adsorption kinetics and adsorption isotherm tests. The maximum fluorine removal efficiency on the loaded materials were that the adsorbent dosage, pH value and adsorption time. They were showed as 1.6 g/L, 3.0 and 240 min, respectively. Dynamics research results showed that the fluoride removal process conformed to pseudo-second order kinetic model. Isothermal adsorption results showed that the fluorine ion adsorption process of Ms-Ce was accord with the Langmuir isotherm adsorption model. The maximum adsorption capacity was 17.96 mg/g. The mainly reaction showed that the active component of cerium carbonate has completed ion exchange with fluoride ion to generate CeCO3F. [ABSTRACT FROM AUTHOR]

The bamboo activated carbon (BAC) was prepared from bamboo charcoal, a commercial product, using microwave radiation with water vapour activation. The surface chemistry and physical characteristics of BAC were investigated by scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area (BET) analyzer, X-Ray Diffraction (XRD), Thermogravimetric differential scanning calorimetry (TG-DSC) curve and fourier transform infrared spectroscopy (FT-IR). The BAC was used for the removal of p-nitrophenol in water. The operational variables including adsorbent dosage, pH, concentration and temperature of solution on the adsorption processes were studied. The BAC regeneration experiments were also carried out. The results showed that the iodine adsorption value was 1099 mg/g and the carbon yield was 34.3% under the optimum conditions. The BAC had a specific surface area of 1168.72 m²/g, total pore volume of 2.203 mL/g and micropore volume of 0.444 ml/g. The removal rate could reach 84% under the BAC dosage of 30 mg and p-nitrophenol solution pH of 5.33. The results of kinetic studies and isothermal adsorption model showed that pseudo-second-order kinetics and Langmuir isothermal adsorption model was well fitted the adsorption equilibrium process. After four times of regeneration, the removal rate could still reach 72%. [ABSTRACT FROM AUTHOR]

In this work, Rhodamine B (RhB) dye was catalytically degraded by using Fenton-like reagent (CNIQ), which was made by self-made multiwalled carbon nanotubes (MWNTs) supported iron oxide FexOy (MWNTs-FexOy) and H2O2. The MWNTs-FexOy was characterized by transmission electron microscope (TEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR), Brunauer, Emmett, and Teller (BET), and X-ray photoelectron spectroscopy(XPS). The factors affecting the degradation of RhBs include the pH value, the reaction temperature, the dosage of MWNTs-FexOy, the dosage of H2O2, the treatment methods, and the concentration of RhB were investigated. Based on the TEM, EDS, FT-IR, BET, and XPS analysis, iron oxide was successfully loaded on carbon nanotubes. The RhB removal rate could reach to 100% under the optimal conditions: the solid to liquid ratio is 1:2, the amount of H2O2 (30%) is 0.1 mL, pH is 3.58, and oscillating time is 60 min. The results also show that the adsorption kinetic of RhB onto MWNTs-FexOy belongs to the pseudo-second-order kinetics. The activation energy and adsorption rate constant are 21.76 kJ/mol and 0.00047 g/(mg min), respectively, the degradation rate increases with the temperature increasing. From this study, we conclude that CNIQ has better adsorption/degradation effect for dye RhB, and it can be used widely in water treatment of textile industry. [ABSTRACT FROM AUTHOR]

In this paper, the Ms-La materials for the fluoride removal performance were characterized using scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier-transform infrared spectrometer (FTIR) and the thermogravimetric analysis-differential temperature analysis (TG-DTA). And the effect of the different dosage, adsorption time, adsorption temperature, pH and coexistence of anions in water was also investigated. The adsorption performance and capacities of Ms-La were investigated through adsorption kinetics and adsorption isotherm tests. The results showed that the maximum fluorine removal efficiency on the loaded materials were that the adsorbent dosage, pH value and the adsorption time were 1.2 g/L, 3.0 and 180 min, respectively. Dynamics research results showed that the fluoride removal process by Ms-La was in accordance with pseudo-secondorder kinetic model and the effect of temperature on adsorption was very little. Isothermal adsorption results showed that the fluorine ion adsorption process of Ms-La was in accordance with the Langmuir isotherm adsorption model, and the maximum adsorption capacity was 19.85 mg/g. The adsorption process of Ms-La is mainly irreversible chemical adsorption, and the main reaction is that the active component of lanthanum carbonate has ion exchange with fluoride ion to generate LaCO3F. [ABSTRACT FROM AUTHOR]

This paper attempts to prepare high-performance activated carbon (HP-AC) from bamboo charcoal (BC) as raw material using microwave irradiation as heating source and potassium hydroxide as activating agent. The influence of factors, such as activation time (3–15 min), KOH/C ratio (1:1–6:1) and particle size (0.147–2 mm) on its performance (the carbon yield and adsorptive capability) were investigated. The textural porosity and surface chemistry of HP-AC were determined by scanning electron microscope (SEM) analyzer, N2 adsorption method and Fourier-transform infrared (FT-IR) spectrometer. The adsorptive properties of HP-AC were examined using iodine solution and methylene blue as model dye compound and hydrogen adsorbate. The effect of porosity and surface functionalities on the electrochemical capacitance of HP-AC were measured by cyclic voltammetry measurements. Under the best preparation conditions (activation time of 8 min, KOH/C ratio of 5:1 and particle size of 0.71–1.4 mm), the following results were obtained for the specific surface area, micro surface area, external surface area, total pore volume, iodine adsorption value, methylene blue adsorption value, carbon yield, hydrogen storage capacity and super capacitance value: 2,446 m² /g, 901 m² /g, 1,545 m² /g, 1.48 mL/g, 2,226 mg/g, 47.5 mL/0.1 g, 34.3%, 0.93 wt% (17.3 MPa, 25°C) and 3.63 wt% (1.0 MPa, −196°C), 212 F/g, respectively. The findings revealed the potential of BC as a raw material for the preparation of HP-AC, and to determine its potential applications of HP-AC as hydrogen storage and super-capacitor material. [ABSTRACT FROM AUTHOR]

In this study, insoluble ammonium phosphotungstate (NH4 PW), which is a photocatalyst, was used to degrade the herbicide chlorothalonil present in aqueous solutions. NH4PW was prepared by both the immersion method (NH4 PW¹ ) and the reflux method (NH4PW² ), and preparing conditions were optimized for degrading chlorothalonil present in aqueous solutions. NH4PW grain sizes are relatively small and well dispersible, when compared with phosphotungstic acid by scanning electron microscope images, while still maintaining the original Keggin structure as can be seen from the results obtained by X-ray diffraction, UV-visible spectra and Fourier transforming infrared spectrum. The efficiency of NH4PW prepared by both methods in degrading chlorothalonil was evaluated. The degradation efficiency of NH4PW¹ and NH4 PW² can reach 73.64% and 55.21%, respectively, under the following conditions: 0.05 g of NH4PW catalysts, 180 min of exposure to UV light and chlorothalonil concentration of 5 mg/L. Moreover, these catalysts showed excellent reproducibility and stability. Catalytic properties did not change significantly when they were calcinated for more than 4 h. Ion chromatographic analysis of the samples further indicated that dissociation occurred in the molecular skeleton of chlorothalonil during the degradation process. The results suggest that ammonium phosphotungstate can be used as a photocatalyst to accelerate the degradation of chlorothalonil present in aqueous solutions and the degradation mechanism of chlorothalonil is discussed in detail in the text. [ABSTRACT FROM AUTHOR]

In this paper, the mesoporous silica (denoted as Ms) was modified by lanthanum and the optimal preparation conditions were investigated for lanthanum loaded mesoporous silica materials (denoted as Ms-La). The Ms-La material was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis-differential temperature analysis (TG-DTA). The results show that lanthanum is successfully loaded onto the surface of the Ms, and the structure of the Ms did not change during the loading process. The Ms-La had good defluorination performance due to its large surface area and good dispersive effect. The defluorination by the Ms-La can reach 81% before optimization and can reach 90% under optimum conditions (nNaHCO3 /nLa = 3.0, nLa/nSi = 0.08 and 90°C drying temperature). The results of isotherm experiments showed that the maximum adsorption capacity was 19.85 mg/g, and the adsorption was in accordance with Langmuir isotherm adsorption model and the adsorption process was mainly based on the replacement of CO32– from La2(CO3)3 by F– to form La(CO3)F. [ABSTRACT FROM AUTHOR]

A commercial multi-walled carbon nanotube (MWCNT) was selected as an adsorbent to remove triazophos, which is a representative insecticide. The MWCNT was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The effect of initial pH value, ionic strength and adsorbent dosage on the adsorption capacity of triazophos was optimized. The adsorption behaviors of triazophos on MWCNT including adsorption kinetics, isotherms and thermodynamics were investigated. The results demonstrated that the adsorption kinetics belonged to the pseudo-second-order and the adsorption rate constant was up to 1.7586 g/min; correlation coefficient was above 0.997. The Freundlich model fits better than Langmuir model, and the maximum adsorption capacity was 42.02 mg/g. The adsorption of triazophos onto MWCNT was thermodynamically feasible and spontaneous. [ABSTRACT FROM AUTHOR]

A novel phenyl-functionalized mesoporous silica based on TiO2 supporter was synthesized to remove bisphenol A (BPA) quickly, which is a representative endocrine disrupting chemical. The prepared sorbents were characterized by nitrogen (N2) adsorption-desorption measurement (BET) and Fourier transform infrared spectroscopy. The effects of the temperature, initial pH value and initial BPA concentration of solution on the adsorption capacity were investigated. And adsorption behaviors of the adsorbent for BPA, such as adsorption kinetics, isotherms, thermodynamics and effect of coexisting pollutants, were also investigated. The result indicated the maximum adsorption capacity of TiO2-Mip-Ms (22 mg g-1) is the two times higher than that of TiO2-Nip-Ms (11 mg g-1), and the Langmuir model fits better than Freundlich model. The adsorption kinetic of BPA onto TiO2-Mip-Ms and TiO2-Nip-Ms belonged to the pseudo-second-order kinetic model, and adsorption rate constant of TiO2-Mip-Ms (0.0156 g mg-1 min-1) is near three times than that of TiO2-Nip-Ms (0.0058 g mg-1 min-1). The BPA adsorption onto TiO2-Mip-Ms was thermodynamically feasible and spontaneous. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) was prepared from the carbon residue of Lugi pressurized gasifier (LPG) slag with a microwave-assisted activation process using potassium hydroxide (KOH) as the activating agent. The effects of various factors such as the heating behavior of the microwave, power of the microwave, activation time and ratio between LPG slag and KOH on the activation have been studied. The surface property of the AC was characterized by BET. The optimal activation conditions were 900 W of microwave power, 9 min of radiation time and 1:1 ratio of KOH and carbon. The surface area of prepared AC was 1061 m² .g–1, and a carbon yield of 42% could be reached. The iodine value was 1082.2 mg g–1. When compared with the traditional method, the microwave-assisted activation process demonstrated faster rate of activation and higher carbon yield. Microwave-assisted AC removed phenols and chromaticity from the wastewater obtained from the Coking Plant in Kunming efficiently. [ABSTRACT FROM AUTHOR]

In this article, we reported a new method in which molybdenum heteropolyacid salt was selected to mix with lanthanum oxide and bentonite, respectively, and the dipping method was used to prepare the new composites of heteropolyacid salt–lanthanum oxide, heteropolyacid salt–bentonite, and heteropolyacid salt–lanthanum oxide–bentonite. We observed that the composites have a better removal effect for phosphorus by control of the ratio and calcination temperature. The effect of quantity, adsorption time, phosphorus wastewater concentration, and pH value of composites on phosphorus adsorption was studied. We also found that the removal rate of phosphorus by the composite of heteropolyacid salt–lanthanum oxides increases up to 99.1% under the condition of 1:1 mass ratio and 500°C of calcination temperature. IR and XRD studies suggest that molybdenum heteropolyacid salt has been loaded to lanthanum oxide carrier successfully and heteropolyacid salt keeps the original Keggin structure. Heteropolyacid salt–lanthanum oxide has a good adsorption effect on phosphorus under the condition of 0.15 g of the composite, 90 min of adsorption time, phosphorus concentration of 50 mg L−1, and pH value of 3. The adsorption of phosphorus corresponds with the Langmuir isotherm model and Lagergren first-order kinetics equation. Therefore, the composite has excellent absorption ability and was competent in removing phosphorus with a low concentration from aqueous solution. It could be a great potential adsorbent for the removal of phosphorus in lakes, rivers, and reservoirs. [ABSTRACT FROM AUTHOR]

In this study, a functionalized zeolites column was developed to remove ammonia nitrogen with a low concentration (50 mg/L) from aqueous solution. The absorption properties and regeneration capacity were investigated. Through breakthrough and elution curve for dynamic adsorption, we found the wastewater with 50mg/L ammonia nitrogen took 7 h to flow 10 g modified zeolites column with diameters of 24 to 64 meshes at a flow rate of 2 mL/min. The saturated extent of adsorption was up to 7.95 mg/g, and the saturated adsorption time was 22 h. The process of dynamic adsorption could be fitted by the Thomas Model. The regeneration ability was optimized by 0.1M Na2CO3 as a regenerant. With excellent absorption ability for removing ammonia nitrogen with a low concentration, the functionalized zeolites could be potentially used a high-performance adsorbent for removing ammonia nitrogen. [ABSTRACT FROM AUTHOR]

A highly sensitive and simple analytical method was developed for analyzing the binary mixed pesticides of prometryne and acetochlor in soil-water system by gas chromatography/ mass spectrometry (GC/MS). The sample solution was first purified by C18 solid-phase extraction column, which was leached by acetone. The leachate was enriched to 1.0mL by pressure blowing concentrator and then analyzed by GC/MS. The linear calibration curves were showed in the range of 1-15 μg/mL with a correlation coefficient of 0.9991. The average recoveries (n = 5) were between 95.3 and 115.7%, with relative standard deviations ranged from 1.71 and 7.95%. The limits of detection of Prometryne/Acetochlor were up to 0.06 and 0.17 μg/mL, respectively. This method provides a reliable approach to examine and evaluate the residues of prometryne and acetochlor in the soil-water system. [ABSTRACT FROM AUTHOR]