Personal Research Database

Full Text: W\Wat Res39, 1663.pdf

Abstract: The overall objective of this research was to determine the effects of physical and chemical activated carbon characteristics on the simultaneous adsorption of trace organic contaminants and natural organic matter (NOM). A matrix of 12 activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels (acid-washed, oxidized, hydrogen-treated, and ammonia-treated) was studied to systematically evaluate pore structure and surface chemistry phenomena. Also, three commercially available granular activated carbons (GACs) were tested. The relatively hydrophilic fuel additive methyl tertiary-butyl ether (MTBE) and the relatively hydrophobic solvent trichloroethene (TCE) served as micropollutant probes. A comparison of adsorption isotherm data collected in the presence and absence of NOM showed that percent reductions of single-solute TCE and MTBE adsorption capacities that resulted from the presence of co-adsorbing NOM were not strongly affected by the chemical characteristics of activated carbons. However, hydrophobic carbons were more effective adsorbents for both TCE and MTBE than hydrophilic carbons because enhanced water adsorption on the latter interfered with the adsorption of micropollutants from solutions containing NOM. With respect to pore structure, activated carbons should exhibit a large volume of micropores with widths that are about 1.5 times the kinetic diameter of the target adsorbate. Furthermore, an effective adsorbent should possess a micropore size distribution that extends to widths that are approximately twice the kinetic diameter of the target adsorbate to prevent pore blockage/constriction as a result of NOM adsorption.

Keywords: Activated Carbon, Adsorption, Drinking Water Treatment, Methyl Tertiary-Butyl Ether (MTBE), Natural Organic Matter, Trichloroethylene (TCE)

? Kostura, B., Kulveitová, H. and Leško, J. (2005), Blast furnace slags as sorbents of phosphate from water solutions. Water Research, 39 (9), 1795-1802.

Full Text: W\Wat Res39, 1795.pdf

Abstract: The paper is focused on the sorption of phosphorus from aqueous solutions by crystalline and amorphous blast furnace slags. Slag sorption kinetics were measured, adsorption tests were carried out and the effect of acidification on the sorption properties of slags was studied. The kinetic measurements confirmed that the sorption of phosphorus on crystalline as well as amorphous slags can be described by a model involving pseudo-second-order reactions. For all slag types, phosphorus sorption follows the Langmuir adsorption isotherm. The acid neutralizing capacities of crystalline and amorphous slags were determined. In the case of the crystalline slags, buffering intervals were found to exist during which the slag minerals dissolve in the sequence bredigite–gehlenite–diaspor. There is a high correlation (R²=0.9989) between ANC_3.8 and the saturation capacities of crystalline and amorphous slags.

Keywords: Phosphate Sorption, Blast Furnace Slag, Sorption Kinetics, Acid Neutralizing Capacity

? Suzuki, Y., Kametani, T. and Maruyama, T. (2005), Removal of heavy metals from aqueous solution by nonliving Ulva seaweed as biosorbent. Water Research, 39 (9), 1803-1808.

Full Text: W\Wat Res39, 1803.pdf

Abstract: The growth of dense green seaweed mats of Ulva spp. is an increasing problem in estuaries and coasts worldwide. The enormous amount of Ulva biomass thus becomes a troublesome waste disposal problem. On the other hand, it has been revealed that nonliving seaweed biomass, particularly brown seaweeds, has a high capacity for assimilating heavy metals. In this study, the possibility of using Ulva seaweed biomass as a biosorbent for the removal of heavy metals was examined. After processing, the biomass material was very easy to separate from the aqueous solution using a mesh. The sorption capacity of Cd on Ulva biomass increased upon pretreatment with alkali solution. The outstanding function of the biosorbent was demonstrated at around pH 8. On the basis of the Langmuir isotherms of Cd, Zn and Cu using the alkali-pretreated biomass, the parameters q_m and b were determined to be within the narrow range of 60–90 mg/g and 0.03–0.04 L/mg, respectively, for each metal. Given the q_m and b values, Ulva seaweed is a good biosorbent material for removing heavy metals. In an experiment using artificial wastewater containing Cd, Zn, Cu, Cr and Ni, it was possible to remove each metal simultaneously using Ulva biomass. Adsorption by Ulva biomass is effective for the removal of heavy metals from wastewater.

Keywords: Ulva Biomass, Biosorbent, Pretreatment, Heavy Metals, Acidic Wastewater

? González-Pradas, E., Socías-Viciana, M., Ureña-Amate, M.D., Cantos-Molina, A. and Villafranca-Sánchez, M. (2005), Adsorption of chloridazon from aqueous solution on heat and acid treated sepiolites. Water Research, 39 (9), 1849-1857.

Full Text: W\Wat Res39, 1849.pdf

Abstract: The adsorption of chloridazon on heat treated sepiolite samples at 110 °C (S-110), 200 °C (S-200), 400 °C (S-400), 600 °C (S-600) and acid treated samples with H₂SO₄ solutions of two different concentrations (0.25 and 1.0 M) (S-0.25 and S-1.0, respectively) from pure water at 25 °C has been studied by using batch experiments. In addition, column experiments were carried out with the natural (S-110) and 600 °C (S-600) heat treated samples, using a 10.30 mg l⁻¹ aqueous solution of chloridazon. The adsorption experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K_f) of the samples; K_f values range from 2.89 mg kg⁻¹ for the S-1.0 sample up to 164 mg kg⁻¹ for the S-600 sample; so, the heat treatment given to the sepiolite greatly increases its adsorption capacity for the herbicide chloridazon whereas the acid treatment produces a clear decrease in the amount of chloridazon adsorbed. The removal efficiency (R) has also been calculated; R values ranging from 5.08% for S-1.0 up to 60.9% for S-600. The batch experiments showed that the strongest heat treatment is more effective than the natural and acid treated sepiolite in relation to adsorption of chloridazon. The column experiments also showed that 600 °C heat treated sepiolite might be reasonably used in removing chloridazon from water. Thus, as this type of clay is relatively plentiful, these activated samples might be reasonably used in order to remove chloridazon from water.

Keywords: Chloridazon, Removal, Sepiolite, Adsorption

? Lee, Y., Yoon, J. and von Gunten, U. (2005), Spectrophotometric determination of ferrate (Fe(Vl)) in water by ABTS. Water Research, 39 (10), 1946-1953.

Full Text: W\Wat Res39, 1964.pdf

Abstract: A new method for the determination of low concentrations (0.03-35 M) of the aqueous ferrate (Fe(VI)) was developed. The method is based on the reaction of Fe(VI) with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) which forms a green radical cation (ABTS center dot(+)) that can be measured spectrophotometrically at 415 nm (ABTS method). The reaction of Fe(VI) with ABTS has a stoichiometry of 1:1 in excess of ABTS (73 M). The increase in absorbance at 415 nm for ABTS center dot(+) generation was linear with respect to Fe(VI) added (0.03-35 M) in buffered solutions (acetate/phosphate buffer at pH = 4.3) and was (3.40±0.05)×10⁴ M^-1 cm^-1. The reaction of Fe(VI) with ABTS was very rapid with a half-life time below 0.01 s at pH 4.3 and 73 M of ABTS. This enables the ABTS method to measure Fe(VI) selectively. The residual absorbance of ABTS center dot(+) was found to be stable in several water matrices (synthetic buffer solution and natural waters) and concentrations of Fe(VI) spiked in natural waters could be determined with high accuracy. The ABTS method can also be used as a tool to determine rate constants of reactions of Fe(VI). The second-order rate constant for the reaction of phenol with Fe(VI) was determined to be 90 M^-1 s^-1 at pH 7. (c) 2005 Elsevier Ltd. All rights reserved.

Keywords: Ferrate, 2,2’-Azino-Bis(3-Ethylbenzothiazoline-6-Sulfonate), ABTS, Analysis, Oxidation, Kinetics, Premix Pulse-Radiolysis, Photometric-Determination, POTASSIUM Ferrate(VI), Hydrogen-Peroxide, Stopped-Flow, Oxidation, Removal, Coagulation, Oxidant, Acids

? Deng, S.B. and Ting, Y.P. (2005), Characterization of PEI-modified biomass and biosorption of Cu(II), Pb(II) and Ni(II). Water Research, 39 (10), 2167-2177.

Full Text: W\Wat Res39, 2167.pdf

Abstract: The objective of this work is to develop a surface-modified biosorbent with enhanced sorption capacity for heavy metal ions. The biomass of Penicillium chrysogenum was modified with polyethylenimine (PEI) and then crosslinked with glutaraldehyde. The crosslingked PEI was chemically bonded on the biomass surface through the amine and carboxylate groups on the pristine biomass. The presence of the amine group was confirmed by X-ray photon spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis, and the concentration of the amine groups on the biomass surface was found to be 2 mmol/g through potentiometric titration. The rugged morphology of the biomass surface after the modification was observed by scanning electron microscope (SEM). Compared with the pristine biomass, the modified biomass with amine groups showed a significant increase in sorption capacity for three metal ions, namely, copper, lead and nickel. The sorption isotherms of the biomass for three metals were well described by Langmuir equation, with a maximum sorption at 92 mg copper, 204 mg lead and 55 mg nickel per g biomass. The binding sites for the three metals attributed to the amine groups on the biomass surface were verified by FTIR analysis.

Keywords: PEI-Modified Biomass, Penicillium Chrysogenum, Crosslinking, Adsorption Performance, Heavy Metals, FTIR and XPS Spectra

Notes: highly cited

? Lindqvist, N., Tuhkanen, T. and Kronberg, L. (2005), Occurrence of acidic pharmaceuticals in raw and treated sewages and in receiving waters. Water Research, 39 (11), 2219-2228.

Full Text: 2005\Wat Res39, 2219.pdf

Abstract: The occurrence of five acidic pharmaceuticals, ibuprofen, naproxen, ketoprofen, diclofenac and bezafibrate, in seven different sewage treatment plants (STP) and three receiving waters were determined. The analytical procedure included solid phase extraction, liquid chromatographic separation and detection by a triple-quadrupole mass spectrometer. The studied pharmaceuticals were found in all the STPs. The pattern of the occurrence of individual compounds was the same in every STP and matched the consumption figures reported in the literature. Ibuprofen is the most used pharmaceutical in Finland and was accordingly found to be the most abundant compound in the raw sewage. In the treatment processes, the highest removal rate was observed for ibuprofen and the lowest for diclofenac, 92% +/- 8% and 26% +/- 17%, respectively. Due to the incomplete removal in the STPs, the pharmaceuticals were found in rivers at the discharge points of the STP effluents. Downstream from the discharge points, the concentrations decreased significantly mainly due to dilution in the river water. The risk to the aquatic environment was estimated by a ratio of measured environmental concentration (MEC) and predicted no-effect concentration (PNEC). At the concentrations the compounds were found in the surface waters, they should not pose risk for the aquatic environment. However, at dry seasons and/or during malfunctions of STPs, ibuprofen could be associated with a risk in small river systems. (c) 2005 Elsevier Ltd. All rights reserved.

Keywords: Pharmaceuticals, Sewage Treatment Plant Influent And Effluent, Discharge To Rivers, Environmental Risk, Clofibric Acid, Surface Waters, Ibuprofen, Residues, Drugs, Carbamazepine, Wastewaters, Environment, Diclofenac, Fate

? Diniz, V. and Volesky, B. (2005), Effect of counterions on lanthanum biosorption by Sargassum polycystum. Water Research, 39 (11), 2229-2236.

Full Text: W\Wat Res39, 2229.pdf

Abstract: The effect of the presence of different anions on the biosorption of La³⁺ (Lanthanum) using Sargassum polycystum Ca-loaded biomass was studied in this work. Different types of metal salts were used, such as nitrate, sulphate and chloride. The presence of the anion sulphate decreased the metal uptake for tested pH values of 3–5 when compared to the nitrate and chloride systems. The presence of chloride ions did not seem to interfere with the lanthanum removal. The speciation of lanthanum in solution could explain the differences obtained for the different systems and the Mineql+ program was used for the calculations. A monovalent complex with sulphate and lanthanum was formed that had lower apparent affinity towards the biomass compared to the free trivalent metal ion. The La uptake varied from 0.6 to 1.0 mmol g⁻¹. The Langmuir model was used to describe quantitatively the sorption isotherms. The addition of sulphuric acid for pH adjustment decreased the metal uptake from lanthanum sulphate solutions when compared to the nitric acid addition. The effect was more pronounced with sulphuric acid due to the formation of complexes.

Keywords: Biosorption, Anions, Lanthanum, Sargassum, Speciation

? Saiano, F., Ciofalo, M., Cacciola, S.O. and Ramirez, S. (2005), Metal ion adsorption by Phomopsis sp. biomaterial in laboratory experiments and real wastewater treatments. Water Research, 39 (11), 2273-2280.

Full Text: W\Wat Res39, 2273.pdf

Abstract: An insoluble material of polysaccharidic nature has been obtained by thermal alkali treatment of the filamentous fungus Phomopsis sp. FT-IR spectrum of the resulting material as well as its nitrogen content suggest that chitosan and glucans are the main components of the biomaterial. Information on Lewis base sites has also been obtained and used as a guideline in the evaluation of the complexing ability against a number of metal ions in aqueous media at pH in the range 4–6. Results indicate that after 24 h contact time, up to 870 μmol/g of lead, 390 μmol/g of copper, 230 μmol/g of cadmium, 150 μmol/g of zinc and 110 μmol/g of nickel ions are adsorbed into the material. After approximately 10 min, about 70% of the overall adsorption process has already been completed. Adsorbed metal ions can be recovered by washing with dilute acid. Experiments have been extended to a real wastewater effluent confirming the potential of this biomaterial as a depolluting agent.

Keywords: Fungal Biomaterial, Chitin, Chitosan, Adsorption Isotherm, Heavy Metal, Wastewater

? Cheng, W., Dastgheib, S.A. and Karanfil, T. (2005), Adsorption of dissolved natural organic matter by modified activated carbons. Water Research, 39 (11), 2281-2290.

Full Text: W\Wat Res39, 2281.pdf

Abstract: Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA₂₅₄) were employed to characterize the DOMs before and after adsorption.

Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA₂₅₄ results showed no specific selectivity in the removal of different DOM components as a result of carbon modification.

The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1–3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs.

Keywords: Activated Carbon, Dissolved Natural Organic Matter (DOM), Surface Chemistry, Surface Modification, Size Exclusion Chromatography (SEC), Specific Ultraviolet Absorbance (SUVA₂₅₄)

? Zhu, X.P. and Jyo, A. (2005), Column-mode phosphate removal by a novel highly selective adsorbent. Water Research, 39 (11), 2301-2308.

Full Text: W\Wat Res39, 2301.pdf

Abstract: A phosphoric acid resin RGP was immobilized with zirconium(IV) (Zr(IV)) to investigate its applicability in phosphate removal. When loaded with Zr(IV), RGP was changed into an effective ligand exchanger with phosphate sorption capacity of 0.345 mmol/ml. Little metal leakage was observed. Breakthrough of phosphate sorption depended on solution acidity and phosphate concentration. An increase of solution pH greatly suppressed phosphate removal, but even at pH 8.21, about 56% of the added phosphate (2.8 mM) in the feed solution could still be sorbed. Electrolytes in the aqueous solution did not interfere with phosphate sorption; on the contrary, an enhancement effect was observed. Due to the high sorption capacity of Zr(IV)-loaded RGP, low concentration of phosphate can be removed at high flow rate (100 h⁻¹ in space velocity). The sorbed phosphate on the Zr(IV)-loaded RGP could be quantitatively eluted with 0.5 M sodium hydroxide solution. The Zr(IV)-loaded RGP is a promising ligand exchanger for treating wastewater containing trace amounts of inorganic phosphate.

Keywords: Phosphate Removal, Ligand Exchange, Water Treatment, Phosphoric Acid Resin

? Pena, M.E., Korfiatis, G.P., Patel, M., Lippincott, L. and Meng, X.G. (2005), Adsorption of As(V) and As(III) by nanocrystalline titanium dioxide. Water Research, 39 (11), 2327-2337.

Full Text: W\Wat Res39, 2327.pdf

Abstract: This study evaluated the effectiveness of nanocrystalline titanium dioxide (TiO₂) in removing arsenate [As(V)] and arsenite [As(III)] and in photocatalytic oxidation of As(III). Batch adsorption and oxidation experiments were conducted with TiO₂ suspensions prepared in a 0.04 M NaCl solution and in a challenge water containing the competing anions phosphate, silicate, and carbonate. The removal of As(V) and As(III) reached equilibrium within 4 h and the adsorption kinetics were described by a pseudo-second-order equation. The TiO₂ was effective for As(V) removal at pH<8 and showed a maximum removal for As(III) at pH of about 7.5 in the challenge water. The adsorption capacity of the TiO₂ for As(V) and As(III) was much higher than fumed TiO₂ (Degussa P25) and granular ferric oxide. More than 0.5 mmol/g of As(V) and As(III) was adsorbed by the TiO₂ at an equilibrium arsenic concentration of 0.6 mM. The presence of the competing anions had a moderate effect on the adsorption capacities of the TiO₂ for As(III) and As(V) in a neutral pH range. In the presence of sunlight and dissolved oxygen, As(III) (26.7 μM or 2 mg/L) was completely converted to As(V) in a 0.2 g/L TiO₂ suspension through photocatalytic oxidation within 25 min. The nanocrystalline TiO₂ is an effective adsorbent for As(V) and As(III) and an efficient photocatalyst.

Keywords: Adsorption, Challenge Water, TiO₂, Photocatalytic Oxidation, Arsenic Speciation

? Jarvie, M.E., Hand, D.W., Bhuvendralingam, S., Crittenden, J.C. and Hokanson, D.R. (2005), Simulating the performance of fixed-bed granular activated carbon adsorbers: Removal of synthetic organic chemicals in the presence of background organic matter. Water Research, 39 (11), 2407-2421.

Full Text: W\Wat Res39, 2407.pdf

Abstract: Granular activated carbon (GAC) adsorption is an effective treatment technology for the removal of synthetic organic chemicals (SOCs) from drinking water supplies. This treatment process can be expensive if not properly designed. Application of mathematical models is an attractive method to evaluate the impact of process variables on process design and performance. Practical guidelines were developed to select an appropriate model framework and to estimate site-specific model parameters to predict GAC adsorber performance. Pilot plant and field-scale data from 11 different studies were utilized to investigate the effectiveness of this approach in predicting adsorber performance in the presence of background organic batter (BOM). These data represent surface and ground water sources from four different countries. The modeling approach was able to adequately describe fixed-bed adsorber performance for the purpose of determining the carbon usage rate and process design variables. This approach is more accurate at predicting bed life in the presence of BOM than the current methods commonly used by practicing engineers.

Keywords: Organic Matter, Activated Carbon, Modeling, Fouling, Synthetic Organic Chemicals

? Walker, G.M., Hanna, J.A. and Allen, S.J. (2005), Treatment of hazardous shipyard wastewater using dolomitic sorbents. Water Research, 39 (11), 2422-2428.

Full Text: W\Wat Res39, 2422.pdf

Abstract: Hazardous shipyard wastewater is a worldwide problem, arising from ship repair. In this study an experimental programme was undertaken to establish the suitability of dolomite and dolomitic sorbent materials to remove contaminants from wastewater arising from a commercial shipyard. Experimental data indicate that dolomite and dolomitic sorbents have the ability to significantly reduce the COD concentration of the shipyard effluent (98% reduction). The data gained from trials at a shipyard indicated that the dolomite treatment process could be undertaken in a 8000 L pilot scale reaction vessel. Analysis of the wastewater using ICP-MS during the pilot trial indicated that the dolomite significantly reduced the concentrations of metallic impurities. The concentration of Sn ions, which is indicative of organo-tin complexes commonly found in shipyard wastewater, was reduced by 80% from its initial concentration in the pilot trial. The mechanism for the removal process using dolomite has been ascribed to a metal complexation/sorption process.

Keywords: Sorption, Hazardous Shipyard Wastewater, Dolomitic Sorbents

? Ahmad, A.L., Sumathi, S. and Hameed, B.H. (2005), Adsorption of residue oil from palm oil mill effluent using powder and flake chitosan: Equilibrium and kinetic studies. Water Research, 39 (12), 2483-2494.

Full Text: W\Wat Res39, 2483.pdf

Abstract: The adsorption of residue oil from palm oil mill effluent (POME) using chitosan powder and flake has been investigated. POME contains about 2 g/l of residue oil, which has to be treated efficiently before it can be discharged. Experiments were carried out as a function of different initial concentrations of residue oil, weight dosage, contact time and pH of chitosan in powder and flake form to obtain the optimum conditions for the adsorption of residue oil from POME. The powder form of chitosan exhibited a greater rate compared to the flake type. The results obtained showed that chitosan powder, at a dosage of 0.5 g/l, 15 min of contact time and a pH value of 5.0, presented the most suitable conditions for the adsorption of residue oil from POME. The adsorption process performed almost 99% of residue oil removal from POME. Equilibrium studies have been carried out to determine the capacity of chitosan for the adsorption of residue oil from POME using the optimum conditions from the flocculation at different initial concentrations of residue oil. Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherm constants. Equilibrium data fitted very well with the Freundlich model. The pseudo first- and second-order kinetic models and intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted well with the second-order kinetic model, which indicates that the chemical sorption is the rate-limiting step, i.e. chemisorption between residue oil and chitosan. The significant uptake of residue oil on chitosan was further proved by BET surface area analysis and SEM micrographs.

Keywords: Chitosan, Residue Oil, Pome, Adsorption Equilibrium, Adsorption Rate

? Shon, H.K., Vigneswaran, S., Ngo, H.H. and Kim, J.H. (2005), Chemical coupling of photocatalysis with flocculation and adsorption in the removal of organic matter. Water Research,