Personal Research Database

Full Text: W\Wat Res38, 2859.pdf

Abstract: Mechanism of chromium adsorption by the persimmon tannin (PT) gel was examined. The PT gel can adsorb Cr highly effectively from aqueous solutions containing Cr(VI), while it adsorbed far smaller amounts of Cr from the solution containing Cr(III). The maximum Cr adsorption from the Cr(VI) solution occurred at pH 3. The Cr adsorption from the Cr(VI) solution by the PT gel was rapid, was faster than VO²⁺ and Fe³⁺ adsorptions, and was obeyed the Langmuir adsorption isotherm (Q_e = 5.27 mmol g^-1 I and K = 16.2 mM). The gel adsorbed Cr from the Cr(VI) solution (pH I and 3) showed no ESR signal of Cr(III), while the ESR signal of Cr(III) was observed in the residual solution at pH 1. Hexavalent chromium was, therefore, adsorbed on the PT gel through the esterification of chromate with catechol group. In other words, Cr(VI) should combine with catechol as a hard acid, CrO₂²⁺ cation. Through the treatment of a Cr(VI) solution with the PT gel, chromium should be recovered as a Cr(IV)-tannin complex at pH 3 or a Cr(III) solution at pH I or lower pH region. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Chromium Adsorption, Persimmon Tannin, Hexavalent Chromium Ion, ESR, Aqueous-Solution, Removal, Biosorption, Cr(VI), Ions

Notes: highly cited

? Carballa, M., Omil, F., Lema, J.M., Llompart, M., García-Jares, C., Rodríguez, I., Gómez, M. and Ternes, T. (2004), Behavior of pharmaceuticals, cosmetics and hormones in a sewage treatment plant. Water Research, 38 (12), 2918-2926.

Full Text: 2004\Wat Res38, 2918.pdf

Abstract: Two cosmetic ingredients (galaxolide, tonalide), eight pharmaceuticals (carbamazepine, diazepam, diclofenac, ibuprofen, naproxen, roxithromycin, sulfamethoxazole and iopromide) and three hormones (estrone, 17β-estradiol and 17α-ethinylestradiol) have been surveyed along the different units of a municipal Sewage Treatment Plant (STP) in Galicia, NW Spain. Among all the substances considered, significant concentrations in the influent were only found for the two musks (galaxolide and tonalide), two anti-inflammatories (ibuprofen and naproxen), two natural estrogens (estrone, 17β-estradiol), one antibiotic (sulfamethoxazole) and the X-ray contrast medium (iopromide), where the other compounds studied were below the limit of quantification. In the primary treatment, only the fragrances (30–50%) and 17β-estradiol (20%) were partially removed. On the other hand, the aerobic treatment (activated sludges) caused an important reduction in all compounds detected, between 35% and 75%, with the exception of iopromide, which remained in the aqueous phase. The overall removal efficiencies within the STP ranged between 70–90% for the fragrances, 40–65% for the anti-inflammatories, around 65% for 17β-estradiol and 60% for sulfamethoxazole. However, the concentration of estrone increased along the treatment due to the partial oxidation of 17β-estradiol in the aeration tank.

Keywords: Activated-Sludge, Adsorption, Anti-Inflammatories, Antibiotics, Antibiotics, Aquatic Environment, Aqueous, Chromatography-Mass Spectrometry, Contaminants, Cosmetics, Elimination, Elsevier, Estrogens, Hormones, Influent, Musk Compounds, Pharmaceuticals, PPCP, Primary, Ray Contrast-Media, Removal, Sewage, Sewage Treatment Plant, Sludge Treatment Works, Solid-Phase Microextraction, Spain, Treatment, Waste-Water, Wastewaters

? Daus, B., Wennrich, R. and Weiss, H. (2004), Sorption materials for arsenic removal from water: A comparative study. Water Research, 38 (12), 2948-2954.

Full Text: 2004\Wat Res38, 2948.pdf

Abstract: Five different sorption materials were tested in parallel for the removal of arsenic from water: activated carbon (AC), zirconium-loaded activated carbon (Zr-AC), a sorption medium with the trade name ‘Absorptionsmittel 3’ (AM3), zero-valent iron (Fe-0), and iron hydroxide granulates (GIH). Batch and column tests were carried out and the behavior of the two inorganic species (arsenite and arsenate) was investigated separately. The sorption kinetics of arsenate onto the materials followed the sequence Zr-ACmuch greater thanGIH=AM3>Fe(0)AC. A different sequence was obtained for arsenite (ACmuch greater thanZr-AC = AM3 = GIH = Fe-0). AC was found to enhance the oxidation reaction of arsenite in anaerobic batch experiments. The linear constants of the sorption isotherms were determined to be 377, 89 and 87 for Zr-AC, AM3 and GIH, respectively. The uptake capacities yielded from the batch experiment were about 7 g l^-1 for Zr-Ac and 5 g l^-1 for AM3.

Column tests indicated that arsenite was completely removed. The best results were obtained with GIH, with the arsenate not eluting before 13 100 pore volumes (inflow concentration I mg l^-1 As) which corresponds to a uptake capacity of 2.3 mg g^-1 or 3.7 g l^-1. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Arsenic, Sorption, Iron Hydroxides, Water Cleaning, Activated Carbon, Kinetics, Samples, Iron, Equilibrium, Adsorption, Adsorbent

Ho, Y.S. (2004), Comment on ‘Cadmium removal from aqueous solutions by chitin: Kinetic and equilibrium studies’. Water Research, 38 (12), 2962-2964.

Full Text: W\Wat Res38, 2962.pdf W\Wat Res-Ho1.pdf

Keywords: Fungus Aspergillus-Niger, Industry Waste-Water, Sphagnum Moss Peat, Sorption Kinetics, Batch System, Metal-Ions, Dye, Lead, Biosorption, Biosorbent

Benaissa, H. (2004), Author’s reply. Water Research, 38 (12), 2965.

Full Text: W\Wat Res38, 2965.pdf

El Zawahry, M.M. and Kamel, M.M. (2004), Removal of azo and anthraquinone dyes from aqueous solutions by Eichhornia Crassipes. Water Research, 38 (12), 2967-2972.

Full Text: W\Wat Res38, 2967.pdf

Abstract: The rate of adsorption of two azo and four anthraquinone anionic dyes on Eichhornia Crassipes (E.C.) has been studied. Raw E.C. and three aminated derivatives of E.C. with different nitrogen percent were used as dye adsorbents. The parameters studied include the amount of substrate, shaking time, chemical structure, concentration of dyestuff and pH of dyeing bath. Simple kinetic adsorption models of dynamics and adsorption parameters for the Langmuir and Freundlich isotherms were determined. A higher nitrogen percent of aminated E.C. showed a higher adsorption capacity than other derivatives. The kinetic adsorption models indicate that the decolourization was complete in a relatively short time (10 min) and the reaction taking place is of the first order. The equilibrium data fit well with the Freundlich model of adsorption for the six dyes. Only dye IV (C.I.A Acid Blue 25) conform both Freundlich and Langmuir adsorption isotherms.

Keywords: Azo Dyes, Anthraquinone Dyes, Eichhornia Crassipes and Its Aminated Derivatives, Dye Adsorbents, Decolourization Freundlich and Langmuir’s Model

Munavalli, G.R. and Mohan Kumar, M.S. (2004), Modified Lagrangian method for modeling water quality in distribution systems. Water Research, 38 (12), 2973-2988.

Full Text: W\Wat Res38, 2973.pdf

Abstract: Previous work has shown that Lagrangian methods are more efficient for modeling the transport of chemicals in a water distribution system. Two such methods, the Lagrangian Time-Driven Method (TDM) and Event-Driven Method (EDM) are compared for varying concentration tolerance and computational water quality time step. A new hybrid method (EDMNET) is developed which improves the accuracy of the Lagrangian methods. All the above methods are incorporated in an existing hydraulic simulation model. The integrated model is run for different network problems under varying conditions. The TDM-generated solutions are affected by both concentration tolerance and water quality time step, whereas EDM solutions are dependent on concentration tolerance. The EDMNET solutions are less sensitive to variations in these parameters. The threshold solutions are determined for all the methods and compared. The hybrid method simulates the nodal concentrations accurately with least maximum segmentation of network and reasonable computational effort as compared to the other Lagrangian methods.

Keywords: Bulk Decay, Distribution System, Dynamic Modeling, Quality Time Step, Concentration Tolerance, Wall Decay, Water Quality

Notes: highly cited

? Sakthivel, S., Shankar, M.V., Palanichamy, M., Arabindoo, B., Bahnemann, D.W. and Murugesan, V. (2004), Enhancement of photocatalytic activity by metal deposition: characterisation and photonic efficiency of Pt, Au and Pd deposited on TiO₂ catalyst. Water Research, 38 (13), 3001-3008.

Full Text: 2004\Wat Res38, 3001.pdf

Abstract: Pt, An and Pd deposited TiO(2) have been prepared and characterised by surface analytical methods such as surface area, XRD, and scanning electron micrograph and photophysical characterisation by diffuse reflectance spectroscopy. The photocatalytic activity of the doped catalysts was ascertained by the photo-oxidation of leather dye, acid green 16 in aqueous solution illuminated with low-pressure mercury lamp (similar to254nm). The effect of metal contents on the photocatalytic activity was investigated. The highest photonic efficiency was observed with metal deposition level of less than 1 wt%. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Photocatalysis, Photo-Oxidation, Photonic Efficiency, Metal-Doped TiO₂, Acid Green 16, Acid Green 16, Heterogeneous Photocatalysis, Leather Dye, Semiconductor Photocatalysis, Water, Photodegradation, Photooxidation, Decomposition, Degradation, Particles

Karapinar, N., Hoffmann, E. and Hahn, H.H. (2004), Magnetite seeded precipitation of phosphate. Water Research, 38 (13), 3059-3066.

Full Text: W\Wat Res38, 3059.pdf

Abstract: Seeded precipitation of Ca phosphate on magnetite mineral (Fe3O4) surfaces was investigated using a Jar Test system in supersaturated solutions at 20degreesC and ionic strength 0.01 mol l^-1 with relative super saturation, 12.0-20.0 for HAP. pH of the solution, initial phosphorus concentration and molar Ca/P ratio were investigated as the main parameters, which effect the seeded precipitation of Ca phosphate. Results showed that there is no pronounced effect of magnetite seed, neither positive nor negative on the amount of calcium phosphate precipitation. pH was found to be the main parameter that determines the phosphate precipitated onto the seed surface. Increasing of the pH of precipitation reaction was resulted in the decrease in percentage amount of phosphate precipitated onto seed surfaces to total precipitation (magnetite seeded precipitation efficiency). It was concluded that the pH dependence of magnetite-seeded precipitation should be considered in the light of its effect on the supersaturated conditions of solution. Saturation index (SI) of solution with respect to the precipitate phase was considered the driving force for the precipitation. A simulation programme PHREEQC (Version 2) was employed to calculate the Saturation-index with respect to hydroxyapatite (HAP) of the chemically defined precipitation system. It was found a good relationship between SI of solution with respect to HAP and the magnetite seeded precipitation efficiency, a second order polynomial function. Results showed that more favorable solution conditions for precipitation (higher SI values of solution) causes homogenous nucleation whereas heterogeneous nucleation led to a higher magnetite seeded precipitation efficiency. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Phosphate Removal, Precipitation, Magnetite, Seeding, Water-Pollution Control, Calcium Phosphates, Crystal-Growth, Separation

Merrifield, J.D., Davids, W.G., MacRae, J.D. and Amirbahman, A. (2004), Uptake of mercury by thiol-grafted chitosan gel beads. Water Research, 38 (13), 3132-3138.

Full Text: W\Wat Res38, 3132.pdf

Abstract: This study describes the synthesis and characterization of thiol-grafted chitosan beads for use as mercury (Hg) adsorbents. Chitosan flakes were dissolved and formed into spherical beads using a phase inversion technique, then crosslinked to improve their porosity and chemical stability. Cysteine was grafted onto the beads in order to improve the adsorption affinity of Hg to the beads. The beads possessed an average diameter of 3.2 mm, porosity of 0.9, specific surface area of similar to 100 m²/g, average pore size of similar to 120 Angstrom, and specific gravity of 2.0. Equilibrium and kinetic uptake experiments were conducted to study the uptake of Hg by the beads. The adsorption capacity was approximately 8.0 mmol-Hg/g-dry beads at pH 7, and decreased with decreasing pH. Hg adsorption kinetics was modeled as radial pore diffusion into a spherical bead with nonlinear adsorption. Use of the nonlinear Freundlich-isotherm in the diffusion equation allowed modeling of the uptake kinetics with a single tortuosity factor of 1.50.3 as the fitting parameter for all initial Hg concentrations, chitosan loadings, and agitation rates. At agitation rates of 50 and 75 rpm, where uptake rate was reduced significantly due to the boundary layer effect, the mass transfer coefficient at the outside boundary was also used as a fitting parameter to model the kinetic data. At agitation rates higher than 150 rpm, pore diffusion was the rate-limiting step. The beads exhibited a high initial uptake rate followed by a slower uptake rate suggesting pore diffusion as the rate-determining step especially at high agitation rates. Higher uptake rates observed in this study compared to those in a previous study of chitosan-based crab shells indicate that dissolution and gel formation increase the porosity and pore accessibility of chitosan. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Chitosan, Hg Removal, Heavy Metals, Sorption, Mass Transfer, Intraparticle Diffusion, Cross-Linking, Heavy-Metals, Sorption, Adsorption, Kinetics, Removal, Equilibrium, Ions, Sorbents, Water

? Barlow, K., Nash, D. and Grayson, R. (2004), Investigating phosphorus interactions with bed sediments in a fluvial environment using a recirculating flume and intact soil cores. Water Research, 38 (14-15), 3420-3430.

Full Text: 2004\Wat Res38, 3420.pdf

Abstract: Phosphorus uptake by bed sediments in surface drains can reduce phosphorus exports from irrigated land. This paper reports on an investigation into the effects of velocity and water depth on phosphorus uptake by bed sediments, which consisted of eight sequential flow events conducted in a recirculating flume as well as a concurrent experiment using sediment cores. For the heavy clay bed sediment discussed in this paper, velocity and depth of water column had no significant effect on net phosphorus uptake and the rates of phosphorus uptake in either the cores or the recirculating flume. The most significant factor affecting phosphorus uptake was the experiment number which represented the sequential nature of experiments within the flume and increasing phosphorus saturation of the surface sediments. Of the kinetic equations used to describe phosphorus uptake (Elovich, boundary layer and diffusion) the Elovich equation provided the best representation of the results, both in terms of the adj-R-2 values and the absence of systematic errors in the residuals. Results suggest that intact soil cores may be used to parameterise rate equations such as the Elovich equation for use in process-based mathematical models of phosphorus transport in fluvial systems. (C) 2004 Elsevier Ltd. All rights reserved.

Keywords: Clay, Column, Depth, Diffusion, Dynamics, Elovich Equation, Environment, Inorganic Phosphorus, Kinetic Equations, Kinetics, Phosphorus, Phosphorus Sorption, Rate Equations, Release, Retention, Sediment, Sediments, Soil, Sorption, Stream, Systematic, Transport, Uptake, Uptake Length, Velocity

Rodríguez, J., Castrillón, L., Marañón, E., Sastre, H. and Fernández, E. (2004), Removal of non-biodegradable organic matter from landfill leachates by adsorption. Water Research, 38 (14-15), 3297-3303.

Full Text: W\Wat Res38, 3297.pdf

Abstract Leachates produced at the La Zoreda landfill in Asturias, Spain, were recirculated through a simulated landfill pilot plant. Prior to recirculation, three loads of different amounts of Municipal Solid Waste (MSW) were added to the plant, forming in this way consecutive layers. When anaerobic digestion was almost completed, the leachates from the landfill were recirculated. After recirculation, a new load of MSW was added and two new recirculations were carried out. The organic load of the three landfill leachates recirculated through the anaerobic pilot plant decreased from initial values of 5108, 3782 and 2560 mg/l to values of between 1500 and 1600 mg/l. Despite achieving reductions in the organic load of the leachate, a residual organic load still remained that was composed of non-biodegradable organic constituents such as humic substances. Similar values of the chemical oxygen demand (COD) were obtained when the landfill leachate was treated by a pressurised anoxic–aerobic process followed by ultrafiltration. After recirculation through the pilot plant, physico-chemical treatment was carried out to reduce the COD of the leachate. The pH of the leachate was decreased to a value of 1.5 to precipitate the humic fraction, obtaining a reduction in COD of about 13.5%. The supernatant liquid was treated with activated carbon and different resins, XAD-8, XAD-4 and IR-120. Activated carbon presented the highest adsorption capacities, obtaining COD values for the treated leachate in the order of 200 mg/l. Similar results were obtained when treating with activated carbon, the leachate from the biological treatment plant at the La Zoreda landfill; in this case without decreasing the pH.

Keywords: Municipal Solid Waste (MSW), Landfill, Leachates, Recirculation, Refractory Organic Matter, Adsorption

Genz, A., Kornmüller, A. and Jekel, M. (2004), Advanced phosphorus removal from membrane filtrates by adsorption on activated aluminium oxide and granulated ferric hydroxide. Water Research, 38 (16), 3523-3530.

Full Text: W\Wat Res38, 3523.pdf

Abstract: The advanced phosphorus (P) removal by adsorption was studied for its suitability as a post-treatment step for membrane bioreactor (MBR) effluents low in P concentration and particle content. Two commercial adsorbents, granulated ferric hydroxide (GFH) and activated aluminium oxide (AA), were studied in batch tests and lab-scale filter tests for P adsorption in MBR filtrates. GFH showed a higher maximum capacity for phosphate and a higher affinity at low P concentrations compared to AA. Competition by inorganic ions was negligible for both adsorbents at the original pH (8.2). When equilibrium P concentrations exceeded 2 mg L⁻¹ in the spiked MBR filtrates, a precipitation of calcium phosphates occurred additionally to adsorption. During column studies the effluent criteria of 50 μg L⁻¹ P was reached after a throughput of 8000 bed volumes for GFH and 4000 for AA. Dissolved organic carbon appears to be the strongest competitor for adsorption sites. A partial regeneration and reloading of both adsorbents could be achieved by the use of sodium hydroxide.

Keywords: Granulated Ferric Hydroxide, Activated Alumina, Aluminium Oxide, Isotherms, Fixed-Bed Adsorption Filters, Phosphorus Removal

Oliveira, L.C.A., Petkowicz, D.I., Smaniotto, A. and Pergher, S.B.C. (2004), Magnetic zeolites: A new adsorbent for removal of metallic contaminants from water. Water Research, 38 (17), 3699-3704.

Full Text: W\Wat Res38, 3699.pdf

Abstract: In this work the adsorption features of NaY zeolite with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as an adsorbent for metallic contaminants in water and subsequently removed from the medium by a simple magnetic process. The zeolites: iron oxide magnetic composites, were prepared by using NaY with weight ratio of 3: 1 and were characterized by powder X-ray diffraction (XRD), magnetization measurements, chemical analyses, N₂ adsorption isotherms and Mössbauer spectroscopy. Nitrogen adsorption isotherms showed that the surface area decreased from 505 m² g⁻¹ for the pure NaY to 353 m² g⁻¹ for the NaY: Fe oxide 3: 1 composite. The adsorption isotherms of metal ions Cr³⁺, Cu²⁺ and Zn²⁺ from aqueous solution onto the composites also showed that the presence of iron oxide does not affect the adsorption capacity.

Keywords: Zeolite, Magnetic Adsorbents, Metallic Contaminants, Magnetic Zeolites

Kundu, S., Kavalakatt, S.S., Pal, A., Ghosh, S.K., Mandal, M. and Pal, T. (2004), Removal of arsenic using hardened paste of Portland cement: Batch adsorption and column study. Water Research, 38 (17), 3780-3790.

Full Text: W\Wat Res38, 3780.pdf

Abstract: Hardened paste of Portland cement (HPPC) has been used as a low-cost adsorbent for the removal of arsenic from water environment. Results from the batch experiments, conducted at an initial concentration of 0.2 ppm of arsenate, suggest arsenate removal up to 95%. Kinetic profiles were developed for various conditions. Effects of adsorbent dose, common ions such as Ca²⁺, Mg²⁺, Fe³⁺, Fe²⁺, Cl⁻, SO₄²⁻, NO₃⁻, PO₄³⁻ and of pH were studied in detail. Adsorption isotherm studies revealed that the Freundlich isotherm was followed with a better correlation than the Langmuir isotherm. Arsenite could also be removed up to 88% using the same material, HPPC. Finally, column studies were undertaken involving the new HPPC to check the suitability of the material for the removal of total arsenic content from water body. Kinetic experiments for the removal of arsenic by column studies revealed a film diffusion mechanism.

Keywords: Portland Cement, Adsorption, Arsenate Removal, Adsorbent, Column Study

Li, Z.K. and Wrenn, B.A. (2004), Effects of ferric hydroxide on the anaerobic biodegradation kinetics and toxicity of vegetable oil in freshwater sediments. Water Research, 38 (18), 3859-3868.

Full Text: W\Wat Res38, 3859.pdf

Abstract: Biodegradation of vegetable oil in freshwater sediments exhibits self-inhibitory characteristics when it occurs under methanogenic conditions but not under iron-reducing conditions. The basis of the protective effect of iron was investigated by comparing its effects on oil biodegradation rate and the toxicity of oil-amended sediments to those of clay and calcium, which reduce the toxicity of oil-derived long-chain fatty acids by adsorption and precipitation, respectively. Kinetic parameters for an integrated mixed-second-order model were estimated by nonlinear regression using cumulative methane production as the response variable and used to compare the effects of the three treatment factors on the rate of oil biodegradation. Ferric hydroxide was the only factor that significantly (P<0.05) increased the rate of methane production from canola oil, whereas calcium significantly reduced the oil biodegradation rate. Measurement of sediment toxicity using the Microtox Solid-Phase Test showed that inhibitory products formed within 5 days of oil addition, but the sediment toxicity decreased over time as the extent of oil mineralization increased. None of the other amendments significantly reduced the toxicity of oil-containing sediments. Since ferric hydroxide stimulated the rate of oil biodegradation without affecting the toxicity of oiled sediments, it must operate through a mechanism that is different from those previously described for clay and calcium.

Keywords: Vegetable Oil, Anaerobic Biodegradation, Kinetics, Freshwater Sediments

? Park, J.H., Feng, Y.C., Cho, S.Y., Voice, T.C. and Boyd, S.A. (2004), Sorbed atrazine shifts into non-desorbable sites of soil organic matter during aging. Water Research,