| 1. |
- Pulkka, Susanna, et al.
(författare)
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Electrochemical methods for the removal of anionic contaminants from water - A review
- 2014
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 132, s. 252-271
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Forskningsöversikt (refereegranskat)abstract
- Different electrochemical methods such as electrocoagulation, electro-oxidation, and electroreduction have been found effective for the removal of various anionic pollutants from water and wastewater. Electrochemical processes can transform contaminants directly or manipulate the redox condition of the environmental matrix to achieve adaptive condition. This review focuses on the removal of different anions, including cyanide, fluoride, nitrate, nitrite, phosphate, and sulfate, from water by electrocoagulation, electro-oxidation, and electroreduction methods. Optimum treatment conditions for studied anions in each electrochemical method are discussed. An overview of electrochemical methods used for anions removal together with specific applications and experimental results are presented and discussed. It is evident from the literature reviewed that these methods have shown considerable potential for the removal of anionic pollutants from water. However, the most challenging issue in this research area is to find out the practical application of these methods on commercial scale, leading to the improvement of pollution control. (C) 2014 Elsevier B.V. All rights reserved.
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| 2. |
- Bhatnagar, Amit, et al.
(författare)
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An overview of the modification methods of activated carbon for its water treatment applications
- 2013
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 219, s. 499-511
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Forskningsöversikt (refereegranskat)abstract
- Activated carbon has been recognized as one of the oldest and widely used adsorbent for the water and wastewater treatment for removing organic and inorganic pollutants. The application of activated carbon in adsorption process is mainly depends on the surface chemistry and pore structure of porous carbons. The method of activation and the nature of precursor used greatly influences surface functional groups and pore structure of the activated carbon. Therefore, the main focus of researchers is to develop or modifies the activation/treatment techniques in an optimal manner using appropriate precursors for specific pollutants. In recent years, emphasis is given to prepare the surface modified carbons using different procedures to enhance the potential of activated carbon for specific contaminants. Various methods such as, acid treatment, base treatment, impregnation treatment, ozone treatment, surfactant treatment, plasma treatment and microwave treatment have been studied to develop surface modified activated carbons. In this paper, these modification methods have been reviewed and the potential of surface modified activated carbons towards water treatment has been discussed. This review article is aimed at providing precise information on efforts made by various researchers in the field of surface modification of activated carbon for water pollution control. (C) 2012 Elsevier B.V. All rights reserved.
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| 3. |
- Bhatnagar, Amit, et al.
(författare)
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Valorization of solid waste products from olive oil industry as potential adsorbents for water pollution control-a review
- 2014
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 21:1, s. 268-298
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Forskningsöversikt (refereegranskat)abstract
- The global olive oil production for 2010 is estimated to be 2,881,500 metric tons. The European Union countries produce 78.5 % of the total olive oil, which stands for an average production of 2,136,000 tons. The worldwide consumption of olive oil increased of 78 % between 1990 and 2010. The increase in olive oil production implies a proportional increase in olive mill wastes. As a consequence of such increasing trend, olive mills are facing severe environmental problems due to lack of feasible and/or cost-effective solutions to olive-mill waste management. Therefore, immediate attention is required to find a proper way of management to deal with olive mill waste materials in order to minimize environmental pollution and associated health risks. One of the interesting uses of solid wastes generated from olive mills is to convert them as inexpensive adsorbents for water pollution control. In this review paper, an extensive list of adsorbents (prepared by utilizing different types of olive mill solid waste materials) from vast literature has been compiled, and their adsorption capacities for various aquatic pollutants removal are presented. Different physicochemical methods that have been used to convert olive mill solid wastes into efficient adsorbents have also been discussed. Characterization of olive-based adsorbents and adsorption mechanisms of various aquatic pollutants on these developed olive-based adsorbents have also been discussed in detail. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.
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| 4. |
- Hokkanen, Sanna, et al.
(författare)
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Adsorption of hydrogen sulphide from aqueous solutions using modified nano/micro fibrillated cellulose
- 2014
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Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 35:18, s. 2334-2346
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, microfibrillated cellulose (MFC) was modified by aminopropyltriethoxysilane (APS), hydroxy-carbonated apatite (HAP), or epoxy in order to produce novel nanostructured adsorbents for the removal of hydrogen sulphide (H2S) from the aqueous solutions. Structural properties of the modified MFC materials were examined using a scanning electron microscope, Fourier transform infrared spectroscopy and acid/base titration. These methods were used to verify the presence of nanostructures on the adsorbents surfaces as well as functionalities suitable for H2S adsorption. Adsorption of H2S by prepared adsorbents was investigated in batch mode under different experimental conditions, i.e. varying pH and H2S concentrations. H2S uptake was found to be 103.95, 13.38 and 12.73mg/g by APS/MFC, HAP/MFC and epoxy/MFC, respectively from 80mg/L H2S solution. The equilibrium data were best described by the Langmuir isotherm for HAP/MFC and APS/MFC and the Sips isotherm for epoxy/MFC.
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| 5. |
- Kumar, Eva, et al.
(författare)
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Interaction of inorganic anions with iron-mineral adsorbents in aqueous media - A review
- 2014
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 203, s. 11-21
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Forskningsöversikt (refereegranskat)abstract
- A number of inorganic anions (e.g., nitrate, fluoride, bromate, phosphate, and perchlorate) have been reported in alarming concentrations in numerous drinking water sources around the world. Their presence even in very low concentrations may cause serious environmental and health related problems. Due to the presence and significance of iron minerals in the natural aquatic environment and increasing application of iron in water treatment, the knowledge of the structure of iron and iron minerals and their interactions with aquatic pollutants, especially inorganic anions in water are of great importance. Iron minerals have been known since long as potential adsorbents for the removal of inorganic anions from aqueous phase. The chemistry of iron and iron minerals reactions in water is complex. The adsorption ability of iron and iron minerals towards inorganic anions is influenced by several factors such as, surface characteristics of the adsorbent (surface area, density, pore volume, porosity, pore size distribution, pH(pzo) purity), pH of the solution, and ionic strength. Furthermore, the physico-chemical properties of inorganic anions (pore size, ionic radius, bulk diffusion coefficient) also significantly influence the adsorption process. The aim of this paper is to provide an overview of the properties of iron and iron minerals and their reactivity with some important inorganic anionic contaminants present in water. It also summarizes the usage of iron and iron minerals in water treatment technology. (C) 2013 Elsevier B.V. All rights reserved.
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| 6. |
- Levchuk, Irina, et al.
(författare)
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Overview of technologies for removal of methyl tert-butyl ether (MTBE) from water
- 2014
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 476, s. 415-433
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Forskningsöversikt (refereegranskat)abstract
- Wide use of methyl tert-butyl ether (MTBE) as fuel oxygenates leads to worldwide environment contamination with this compound basically due to fuel leaks from storage or pipelines. Presence of MTBE in drinking water is of high environmental and social concern. Existing methods for MTBE removal from water have a number of limitations which can be possibly overcome in the future with use of emerging technologies. This work aims to provide an updated overview of recent developments in technologies for MTBE removal from water. (C) 2014 Elsevier B.V. All rights reserved.
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| 7. |
- Rengaraj, Selvaraj, et al.
(författare)
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Cauliflower-like CdS Microspheres Composed of Nanocrystals and Their Physicochemical Properties
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:1, s. 352-358
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Tidskriftsartikel (refereegranskat)abstract
- Cauliflower-like cadmium sulfide (CdS) microspheres composed of nanocrystals have been successfully synthesized by a hydrothermal method using poly(ethylene glycol) (PEG) as the template coordination agent and characterized by a variety of methods. Our experiments confirmed that the size of the CdS microspheres could be easily modified by controlling the chain length of PEG. Powder X-ray diffraction and Raman spectroscopy measurements revealed the cubic structure of the CdS microspheres; morphological studies performed by HR-SEM and HR-TEM methods showed the cauliflower-like structure of the synthesized CdS microspheres. Each microsphere was identified to be created by the self-assembly of CdS nanocrystals and is attributed to the oriented aggregation of the CdS nanocrystals around a polymer-Cd(2+) complex spherical framework structure. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray (EDX) analysis confirmed the stoichiometries of the CdS microspheres. Diffuse reflectance spectrum (DRS) measurements showed that increasing the PEG chain length increased the band gap value of the CdS microspheres slightly, from 1.99 to 2.06 eV. The cauliflower-like CdS microspheres could be applied to photocatalytic degradation studies.
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| 8. |
- Rengaraj, Selvaraj, et al.
(författare)
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Self-Assembled Mesoporous Hierarchical-like In(2)S(3) Hollow Microspheres Composed of Nanofibers and Nanosheets and Their Photocatalytic Activity
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:9, s. 5534-5541
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Tidskriftsartikel (refereegranskat)abstract
- Novel template-free hierarchical-like In(2)S(3) hollow microspheres were synthesized using thiosemicarbazide (NH(2)NHCSNH(2)) as both a sulfur source and a capping ligand in a ethanol/water system. In this study, we demonstrate that several process parameters, such as the reaction time and precursor ratio, strongly influence the morphology of the final product. The In(NO(3))(3)/thiosemicarbazide ratios were found to effectively play crucial roles in the morphologies of the hierarchical-like In(2)S(3) hollow microsphere nanostructure. With the ratios increasing from two to four, the In(2)S(3) crystals exhibited almost spherical morphologies. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS). XRD analysis confirmed the tetragonal structure of the In(2)S(3) hollow microspheres. The products show complex hierarchical structures assembled from nanoscale building blocks. The morphology evolution can be realized on both outside (surface) and inside (hollow cavity) the microsphere. The surface area analysis showed that the porous In(2)S(3) possesses a specific surface area of 108 m(2)/g and uniform distribution of pore sizes corresponding to the size of pores resulting from the self-assembled structures with flakes. The optical properties of In(2)S(3) were also investigated by UV-vis DRS, which indicated that our In(2)S(3) microsphere samples possess a band gap of similar to 1.96 eV. Furthermore, the photocatalytic activity studies revealed that the synthesized In(2)S(3) hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that In(2)S(3) hollow microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.
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| 9. |
- Repo, Eveliina, et al.
(författare)
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Aminopolycarboxylic acid functionalized adsorbents for heavy metals removal from water
- 2013
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:14, s. 4812-4832
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Forskningsöversikt (refereegranskat)abstract
- Due to the excellent chelating properties of aminopolycarboxylic acid (APCAs), they can be used for the removal of metals from contaminated waters. This paper reviews the research results obtained for both commercial and self-prepared adsorbents functionalized with four most common APCAs: iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA). The structural characteristics and unique metal binding properties of these chelating adsorbents are presented. The theory of the adsorption phenomena is discussed based on the kinetics of adsorption, equilibrium adsorption isotherm models, and thermodynamic models. The most important applications of APCA-functionalized adsorbents are also described. APCA-functionalized adsorbents are found to be highly promising materials for metal removal from contaminated waters. (C) 2013 Elsevier Ltd. All rights reserved.
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| 10. |
- Selvaraj, Rengaraj, et al.
(författare)
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A simple hydrothermal route for the preparation of HgS nanoparticles and their photocatalytic activities
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:30, s. 15371-15376
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Tidskriftsartikel (refereegranskat)abstract
- HgS nanoparticles have been successfully prepared by a hydrothermal method using polyethylene glycol (PEG) as stabilizing agent and characterized by a variety of methods. Our experiments confirmed that the size of the HgS nanocrystals could be easily modified by tuning the chain length of PEG. X-ray powder diffraction (XRD) results for the nanoparticles revealed the hexagonal structure of the HgS, i. e. a-phase known as cinnabar. Morphological studies performed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the synthesized nanocrystals were nanoparticles. Furthermore, a rational mechanism of the formation and evolution of the products was proposed. The optical properties of HgS were investigated by diffuse reflectance spectroscopy (DRS), which indicated that the band gap of the nanoparticles is slightly decreased from 2.05 to 2.00 eV as the average particle size decreases from 55 to 35 nm. Furthermore, the photocatalytic activity studies of the particles demonstrated their excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that HgS nanoparticles will be an interesting candidate of photocatalyst working in visible light range.
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