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1.
Water Environ Res ; 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31650659

RESUMO

A p-type TiO2 with Ti vacancies (D-TiO2 ) was synthesized by a facile solvothermal treatment, and Ag/TiO2 with different Ag loading amount was prepared through a photo-reduction deposition method. The samples were characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The adsorption and photocatalytic characteristics of tetrabromobisphenol A (TBBPA) on D-TiO2 and Ag/TiO2 were investigated. The adsorption of TBBPA on Ag/TiO2 was significantly enhanced and was five times greater than that of pure TiO2 . The increase in pH significantly inhibited the adsorption of TBBPA. The 2%-Ag/TiO2 nearly completely degraded TBBPA in 10 min under UV-Vis light (λ > 360 nm), and the apparent reaction rate constant (kapp ) reached 0.63 min-1 . The significantly enhanced UV-Vis light catalytic properties of the Ag/TiO2 in comparison with that of TiO2 were attributed to the increased adsorption capacity and electron transfer ability of the Ag/TiO2 . Free radical trap experiments results showed that holes and superoxide radicals play a major role in the catalytic degradation of TBBPA by Ag/TiO2 . Moreover, the Ag/TiO2 catalyst exhibits high stability during TBBPA degradation even after three cycles. PRACTITIONER POINTS: Ti-defected TiO2 and Ag/TiO2 were synthesized using a solvothermal and photo-reduction deposition, respectively. Ag/TiO2 exhibited outstanding adsorption and photocatalytic activity for TBBPA removal under UV-Vis light. Holes and superoxide radicals play a major role in the photocatalytic degradation of TBBPA.

2.
Chemosphere ; 208: 800-807, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29906754

RESUMO

In order to develop promising sorbents for value-added application of solid wastes, low-cost aluminum-enriched biochar was prepared from abandoned Tetra Pak used to hold milks, a paper-polyethylence-Al foil laminated package box, after acid pretreatment and subsequent slow pyrolysis under an oxygen-limited environment at 600 °C. The basic physicochemical properties of the resultant biochar were characterized and the sorption performance of aqueous As(III) and As(V) was investigated via batch and column sorption experiments. Carbon (49.1%), Ca (7.41%) and Al (13.5%) were the most abundant elements in the resultant biochar; and the specific surface area and the pH value at the point of zero charge (pHPZC) were 174 m2 g-1 and 9.3, respectively. Batch sorption showed excellent sorption performance for both As(III) (24.2 mg g-1) and As(V) (33.2 mg g-1) and experimental data were fitted well with Langmuir model for the sorption isotherms and pseudo-second order kinetic model for the sorption kinetics. The residual concentrations of As(V) after sorption were below the limited value of arsenic in WHO Guidelines for Drinking water Quality (0.01 mg L-1) even if coexistence of PO43-. Column sorption confirmed the high sorption performance for As(III) and As(V). So the slow pyrolysis of abandoned Tetra Paks as low-cost and value-added sorbents is a sustainable strategy for solid waste disposal and wastewater treatment.


Assuntos
Arsênico/química , Carvão Vegetal/química , Adsorção , Alumínio , Poluentes Químicos da Água/análise , Purificação da Água/métodos
3.
Huan Jing Ke Xue ; 38(5): 1947-1956, 2017 May 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965100

RESUMO

A novel composite adsorbent (Ti-Zr-D201) for simultaneous removal of phosphate and fluoride from water was prepared by loading nanosized titanium and zirconium oxides on the anion exchange resin named D201. Combining with the characterization of the adsorbent, adsorption isotherm experiments, effect of solution pH experiments, competitive tests, kinetic experiments and fixed bed column adsorption experiments were performed to explore the adsorption performance and mechanism. The maximum adsorption capacity of Ti-Zr-D201 for phosphorus and fluorine was 34.9mg·g-1 and 35.1mg·g-1 respectively, when the pH value was 5.8 and the temperature was 308K. Adsorption behavior was spontaneous, and higher temperature was favorable for phosphorus and fluoride adsorption. The effect of pH on the adsorption of fluoride was more significant compared with the adsorption of phosphorus. SO42-, NO3- and Cl- were selected as the competitive ions for competition experiments, and the results indicated that Ti-Zr-D201 exhibited favorable sorption selectivity for phosphorus and fluoride compared with the host material D201. The fitting results of the internal diffusion model showed that there were two different adsorption stages before the adsorption equilibrium of Ti-Zr-D201. Column adsorption experiments showed that Ti-Zr-D201 had a stable structure, excellent dynamic adsorption performance, and could be recycled, which showed the potential of practical application.

4.
J Environ Sci (China) ; 26(2): 307-14, 2014 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-25076522

RESUMO

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides (HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents (denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 microg/L to below 5 microg/L (the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.


Assuntos
Antimônio/isolamento & purificação , Compostos Férricos/química , Adsorção , Resinas de Troca de Ânions/química , Carbonato de Cálcio/química , Concentração de Íons de Hidrogênio , Concentração Osmolar
5.
Environ Sci Technol ; 48(9): 5101-7, 2014 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-24730751

RESUMO

Hydrous manganese oxide (HMO) is generally negatively charged at circumneutral pH and cannot effectively remove anionic pollutants such as phosphate. Here we proposed a new strategy to enhance HMO-mediated phosphate removal by immobilizing nano-HMO within a polystyrene anion exchanger (NS). The resultant nanocomposite HMO@NS exhibited substantially enhanced phosphate removal in the presence of sulfate, chloride, and nitrate at greater levels. This is mainly attributed to the pHpzc shift from 6.2 for the bulky HMO to 10.5 for the capsulated HMO nanoparticles, where HMO nanoparticles are positively charged at neutral pH. The ammonium groups of NS also favor phosphate adsorption through the Donnan effect. Cyclic column adsorption experiment indicated that the fresh HMO@NS could treat 460 bed volumes (BV) of a synthetic influent (from the initial concentration of 2 mg P[PO4(3-)]/L to 0.5 mg P[PO4(3-)]/L), while only 80 BV for NS. After the first time of regeneration by NaOH-NaCl solution, the capacity of HMO@NS was lowered to ∼ 300 BV and then kept constant for the subsequent 5 runs, implying the presence of both the reversible and irreversible adsorption sites of nano-HMO. Additional column adsorption feeding with a real bioeffluent further validated great potential of HMO@NS in advanced wastewater treatment. This study may provide an alternative approach to expand the usability of other metal oxides in water treatment.


Assuntos
Compostos de Manganês/química , Óxidos/química , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão , Nanopartículas , Espectrofotometria Ultravioleta
6.
J Environ Monit ; 12(1): 305-10, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20082026

RESUMO

Selenite (SeO(3)(2-)) is an oxyanion of environmental significance due to its toxicity when taken in excess. In the present study, a hybrid adsorbent (HFO-201) was prepared by irreversibly impregnating hydrated ferric oxide (HFO) nanoparticles within a commercial available anion-exchange resin (D-201), and its adsorption towards selenite from water was investigated in batch and column tests. HFO-201 exhibited improved sorption selectivity toward selenite as compared to the polymeric anion exchanger D-201. Two possible adsorption interactions were responsible for selenite removal by HFO-201, the electrostatic interaction from the ammonium groups bound to the D-201 matrix, and the formation of inner-sphere complexes between the loaded HFO nanoparticles and selenite. In a wide pH range (i.e., 3-8), increasing solution pH was found to result in a decrease of selenite removal on HFO-201. Adsorption isotherms fit the Freundlich model well, and selenite adsorption increased with increasing ambient temperature, indicating its endothermic nature. Column adsorption tests suggested that satisfactory removal of selenite from 2 mg/L to less than 0.01 mg/L could be achieved by HFO-201 even in the presence of the commonly encountered anionic competition at greater concentration, with the treatment capacity of approximately 1200 bed volume (BV) per run, while that for D-201 was only less than 30 BV under otherwise identical conditions. Furthermore, the exhausted HFO-201 was amenable to efficient in situ regeneration with a binary NaOH-NaCl solution.


Assuntos
Compostos Férricos/química , Polímeros/química , Selenito de Sódio/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Amônia/química , Resinas de Troca de Ânions , Concentração de Íons de Hidrogênio , Cinética , Microscopia Eletrônica de Varredura , Nanopartículas/química , Tamanho da Partícula , Cloreto de Sódio/química , Hidróxido de Sódio/química , Selenito de Sódio/química , Eletricidade Estática , Termodinâmica , Poluentes Químicos da Água/química , Purificação da Água/instrumentação
7.
Water Res ; 44(3): 815-24, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19906397

RESUMO

The present study developed a polymer-based hybrid sorbent (HFO-001) for highly efficient removal of heavy metals [e.g., Pb(II), Cd(II), and Cu(II)] by irreversibly impregnating hydrated Fe(III) oxide (HFO) nanoparticles within a cation-exchange resin D-001 (R-SO(3)Na), and revealed the underlying mechanism based on X-ray photoelectron spectroscopy (XPS) study. HFO-001 combines the excellent handling, flow characteristics, and attrition resistance of conventional cation-exchange resins with the specific affinity of HFOs toward heavy metal cations. As compared to D-001, sorption selectivity of HFO-001 toward Pb(II), Cu(II), and Cd(II) was greatly improved from the Ca(II) competition at greater concentration. Column sorption results indicated that the working capacity of HFO-001 was about 4-6 times more than D-001 with respect to removal of three heavy metals from simulated electroplating water (pH approximately 4.0). Also, HFO-001 is particularly effective in removing trace Pb(II) and Cd(II) from simulated natural waters to meet the drinking water standard, with treatment volume orders of magnitude higher than D-001. The superior performance of HFO-001 was attributed to the Donnan membrane effect exerted by the host D-001 as well as to the impregnated HFO nanoparticles of specific interaction toward heavy metal cations, as further confirmed by XPS study on lead sorption. More attractively, the exhausted HFO-001 beads can be effectively regenerated by HCl-NaCl solution (pH 3) for repeated use without any significant capacity loss.


Assuntos
Compostos Férricos/química , Metais Pesados/isolamento & purificação , Nanopartículas/química , Tamanho da Partícula , Espectroscopia Fotoeletrônica/métodos , Polímeros/química , Água/química , Adsorção , Cálcio/química , Cátions , Galvanoplastia , Meio Ambiente , Concentração de Íons de Hidrogênio , Resinas de Troca Iônica/química , Íons , Cinética , Nanopartículas/ultraestrutura , Soluções , Temperatura Ambiente , Fatores de Tempo , Eliminação de Resíduos Líquidos
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