Search

Acetaminophen can increase the risk of arsenic-mediated hepatic oxidative damage; therefore, the decontamination of water polluted with coexisting acetaminophen and arsenic gives rise to new challenges for the purification of drinking water. In this work, a three-metal layered double hydroxide, namely, Cu-Zn-Fe-LDH, was synthesized and applied as a heterogeneous Fenton-like oxidation catalyst and adsorbent to simultaneously remove acetaminophen (Paracetamol, PR) and arsenic. The results showed that the degradation of acetaminophen was accelerated with decreasing pH or increasing H2O2 concentrations. Under the conditions of a catalyst dosage of 0.5 g·L(-1) and a H2O2 concentration of 30 mmol·L(-1), the acetaminophen in a water sample was completely degraded within 24 h by a Fenton-like reaction. The synthesized Cu-Zn-Fe-LDH also exhibited a high efficiency for arsenate removal from aqueous solutions, with a calculated maximum adsorption capacity of 126.13 mg·g(-1). In the presence of hydrogen peroxide, the more toxic arsenite can be gradually oxidized into arsenate and adsorbed at the same time by Cu-Zn-Fe-LDH. For simulated water samples with coexisting arsenic and acetaminophen pollutants, after treatment with Cu-Zn-Fe-LDH and H2O2, the residual arsenic concentration in water was less than 10 μg·L(-1), and acetaminophen was not detected in the solution. These results indicate that the obtained Cu-Zn-Fe-LDH is an efficient material for the decontamination of combined acetaminophen and arsenic pollution.

Magnetic iron oxide/carbon nanotube (MI-CNT) hybrids have been successfully synthesized through a simple solid-phase method by using as-prepared CNTs (APCNTs). To further enhance the adsorption capacity for AsIII, MI-CNTs were subsequently functionalized by using an amino acid derivative (glutathione (GSH)) through a facile chemical route. CNTs not only act as a support for iron oxide but also significantly contribute to arsenic removal. The resulting GMI-CNTs possess simultaneously a high adsorption capacity and desirable magnetic properties, thus making them promising for use as an adsorbent to remove AsIII with significantly enhanced adsorption capacity (19.12 mg g−1) and desired magnetic separation properties ( Ms=27.3 emu g−1). Adsorption studies indicated that the active sites on the surface of GMI-CNTs for AsIII are heterogeneous owing to the multiphase of Fe and the GSH functionalization. Therefore GMI-CNTs can potentially be used as a practical adsorbent for the decontamination of AsIII in water. The results of this study are highly important for practical applications of as-prepared CNTs that contain catalyst nanoparticles. [ABSTRACT FROM AUTHOR]

A composite adsorbent MIR, manganese and iron (hydr)oxides coated resin, was prepared by coating manganese and iron (hydr)oxides onto the weak basic anion exchange resin D301. The effects of solution pH, contact time, ionic strength, and coexisting ions on arsenate removal with MIR were investigated in batch experiments. The results showed that As(V) can be effectively removed in a wide pH range of 4 ∼ 9. The presence of coexisting anions such as [image omitted] had no noticeable effect on arsenate removal efficiency. However, [image omitted] were found to interfere with the arsenate removal significantly. Arsenate adsorption efficiency decreased with the increment of ion strength of the solution. The adsorption isotherm could be well described by the Freundlich model. A pseudo second-order kinetics was able to provide a realistic description of the adsorption kinetics. [ABSTRACT FROM AUTHOR]

Domestic water purification devices (point-of-use) are important choices for people to deal with sudden drinking water contamination. Especially for sudden heavy metal and arsenic contamination, home water purification units can play a key role as a secondary line of defense. Most of the arsenic removal studies are limited to meeting the requirements of local water quality standards and few studies have been conducted on arsenic removal from household water purifiers. In this paper, the distribution characteristics of arsenic in water at the end of the pipeline network in the Shanghai water supply area have been investigated. Three types of household water purifiers, mainly with membrane separation technology, were selected to treat the simulated arsenic contamination in tap water sources. The effects of pH and inorganic salts on arsenic removal were studied in comparison to the results of coexisting ion concentrations in tap water. The results showed that the total arsenic concentrations in different tap water samples range from 0.479–1.195 µg L−1, which is lower than the limit value for arsenic concentration set by China's drinking water standard GB 5749–2006 (10 µg L−1) and by the World Health Organization (10 µg L−1). It is found that reverse osmosis and nanofiltration water purifiers were more effective in removing As(V), with removal rate above 97.7%, and less effective in removing As(III), the rate ranging from 40.1 to 56.3%. Preliminary validation was provided for the safety of household water purifiers in securing universal and sudden drinking water contamination. Domestic water purifiers are effective in reducing the risk of arsenic exposure in drinking water. [ABSTRACT FROM AUTHOR]

A series of calcium-containing layered double hydroxides (LDHs) and calcined product (CLDH) were synthesized using a comparative simple synthesis method (without using organic solvents and with a shortened reaction time) and applied in the adsorption of arsenic in water. The adsorption performance of arsenate on these LDHs and CLDH were studied using batch tests. The effects of various factors during the adsorption process, such as pH of the solution, dosage of materials, coexisting ions, contact time, and initial arsenate concentration, were evaluated. The maximum adsorption capacity of arsenate on three materials (CaFe-CLDH, CaFe-Cl-LDH, CaFe-NO3-LDH) were 156.0 mg·g−1, 150.5 mg·g−1, and 148.0 mg·g−1, respectively. When the concentration of CaFe-CLDH was 0.5 g·L−1, the concentration of arsenate was reduced from 5000 μg·L−1 to 10 μg·L−1 after adsorption. Moreover, when the CaFe-NO3-LDH or CaFe-Cl-LDH dosage was 1.0 g·L−1, a similar decontamination result could be achieved. The synthesized CaFe-CLDH was used to treat actual contaminated water samples from a river in a mining area north of Lengshuijiang City in Hunan Province, China. After treating using CaFe-CLDH, the residual arsenic concentration of actual water samples can fully meet the requirements for arsenic in the drinking water standards of the World Health Organization and China. This indicates that synthetic CaFe-CLDH has the potential to serve as an effective adsorbent for the removal of arsenic contamination. [ABSTRACT FROM AUTHOR]

The coexistence of pharmaceuticals and arsenic in natural water may exhibit a synergistic toxic effect on humans or animals. Therefore, efficient simultaneous removal of pharmaceuticals (paracetamol as a target pollutant) and arsenic from water has received increasing attention. In this study, the novel calcined ZnFe-layered double hydroxides/reduced graphene oxide (ZnFe-CLDH/RGO) composites are fabricated via a hydrothermal-calcination method. The obtained ZnFe-CLDH/RGO composites exhibit significantly improved photocatalytic performance toward degradation of paracetamol as compared to the pristine ZnFe-CLDH. The photocatalytic activity of the screened ZnFe-CLDH/RGO30 material for paracetamol degradation is about 3.5 times that of ZnFe-CLDH. The improved photocatalytic activity could be attributed to the RGO, which could lead to increased pollutant adsorption capacity and enhanced charge separation efficiency. The magnetic ZnFe-CLDH/RGO composite also shows excellent stability and reusability as a promising photocatalyst. For As(III) removal, the ZnFe-CLDH/RGO composite displays better removal efficiency in the light than in the dark. It should be ascribed to the synergy of photocatalytic oxidation of As(III) to less toxic As(V) and the accompanying arsenic adsorption. Interestingly, our study indicates that the paracetamol degradation in the mixed system of paracetamol/As(III) is more efficient than that in the single system of paracetamol. Meanwhile, arsenic can be also efficiently removed from the water samples with coexistent paracetamol and As(III) species. This work may provide a promising composite for the efficient simultaneous elimination of water environmental inorganic anions and organic pollutants. [ABSTRACT FROM AUTHOR]

A series of ZnFe-MMOs were synthesized by in situ topotactic transformation of ZnFe-LDH precursors, and screened for obtaining an efficient functional material used in the simultaneous removal of pharmaceuticals and arsenic. In a mono-component system, the photodegradation efficiency of ibuprofen with optimal ZnFe-MMOs can reach 95.7% under simulated solar irradiation and the maximum adsorption capacity of arsenic was up to 176.3 mg·g −1 . In the binary system of ibuprofen and arsenic, the degrading activity of ibuprofen inordinately decreased depending on both the arsenic species and concentrations, while the presence of ibuprofen had no significant impact on arsenic removal. The potential application of ZnFe-MMOs for the simultaneous removal of several pharmaceuticals (ibuprofen, acetaminophen and diclofenac) and arsenic in actual water matrix was also investigated. After 12 h, arsenic concentration decreased from 1000 to 1.61 μg·L −1 and no pharmaceutical was detected. Possible mechanisms were revealed, indicating that photogenerated h + was primary reactive species for the photodegradation of ibuprofen, and arsenic species including As(III) and As(V) were removed by the combination of photocatalytic oxidation and surface complexation adsorption. Furthermore, ZnFe-MMOs exhibited good reusability after regeneration, rendering it a promising multi-functional material for the decontamination of polluted water with the coexistent pharmaceuticals and arsenic pollutants. [ABSTRACT FROM AUTHOR]

This study proposes the use of a Zn/Fe layered double hydroxide (Zn–Fe-LDH) material to achieve the simultaneous and efficient removal of As(V) and Sb(V) in aqueous solutions. The Zn–Fe-LDH material has been synthesized by a co-precipitation method and used to remove arsenate and antimonate in both simulated and practical polluted water samples. The adsorption performances were studied by batch experiments and column tests. The experimental result of simulated water samples showed that the adsorption of As(V) or Sb(V) onto Zn–Fe-LDH material can be well described by the Sips isotherm model. It was found that the maximum adsorption capacity for As(V) and Sb(V) in single pollutant system was 151.37 mg g − 1 and 122.03 mg g − 1 , respectively. When the adsorbent dosage was 0.2 g L − 1 , the batch experiments showed that the residual concentration of arsenic or antimonate can be decreased from 2 mg L − 1 to lower than 0.005 mg L − 1 . For the practical polluted water samples from Xikuangshan area, the result showed that the dosage of 0.2 g L − 1 Zn–Fe-LDH can make both the arsenic and antimony residual concentrations meet the limit value of drinking water standard recommended by WHO. It is deduced from the column tests that 1 kg Zn–Fe-LDH material might treat 12,500 L polluted water from1 mg L − 1 arsenate and 1 mg L − 1 antimonate to the level below 10 μg L − 1 and 5 μg L − 1 simultaneously. It is demonstrated that the synthesized Zn–Fe-LDH material is a potential attractive adsorbent for the simultaneous removal of As(V) and Sb(V) in water. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) functionalized with magnetic nanoparticles are attractive for environmental remediation applications due to their high specific surface area conducive for adsorption of water contaminants and the possibility of recovering these nanohybrids after remediation using an external magnetic field. Most of existing methods for synthesizing magnetic iron oxide/CNTs (MIO–CNTs) composites are carried out in the liquid medium and are tedious, uneconomical, and environmentally unfriendly. Herein, we report a one-pot solid-phase route to synthesize MIO–CNTs composites based on pristine CNTs. MIO–CNTs possess a high specific surface area, good dispersibility, and desirable magnetic properties, making them promising as adsorbents for arsenic removal. The maximum arsenic adsorption capacities are 47.41 and 24.05 mg g − 1 for As(V) and As(III), respectively. These values are among the highest for carbon-based materials. Oxygen-containing groups on the surface of MIO–CNTs play a crucial role in arsenic adsorption. This work is very important for the practical applications of pristine CNTs containing catalyst nanoparticles without the need of purifications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ferric-based layered double hydroxide intercalated with α-alanine was synthesized. [•] Mg-Fe-Ala-LDH showed much higher adsorption capacity for As(III) than for As(V). [•] Desorption experiments indicated As(III) had stronger affinity to Mg-Fe-Ala-LDH. [•] The obtained Mg-Fe-Ala-LDHs is a potential efficient adsorbent for arsenic removal. [ABSTRACT FROM AUTHOR]

Abstract: The mesoporous Ce–Fe bimetal oxide (MCFO) was synthesized through a soft-template method and first applied in the adsorption of arsenate in aqueous solutions. The synthesized MCFO was characterized with BET surface area, X-ray diffraction (XRD), zeta potential, scanning electron microscope (SEM), and Fourier transform infrared (FTIR) analysis. The mesoporous structure of the MCFO was determined according to the characterization result. The adsorption efficiency of arsenate ions on the MCFO was studied as a function of initial As(V) concentration, contact time, pH, and coexistent anions. It was found that the adsorption isotherms could be well described by Langmuir model, and the calculated maximum adsorption capacity of MCFO-1 for As(V) was 91.74mgg−1, which was significantly greater than that of ordinary Ce–Fe bimetal oxide (CFO). The results showed that the adsorption kinetic data obeyed the pseudo-second order model. Lower pH was favorable for As(V) adsorption on the MCFO. Coexistent phosphate ions exhibited an obvious interference on As(V) adsorption, followed by silicate and fluoride ions. The analysis of BET and FTIR indicated that the high efficiency of As(V) adsorption on this Ce–Fe bimetal oxide (MCFO) was closely related to its uniform mesoporous structure and abundant surface hydroxyl groups. [Copyright &y& Elsevier]