Effect Of Competing Ions Research Articles

Environmentally friendly nanoflower Al2O3@carbon spheres as adsorbent for dispersive solid-phase microextraction of copper and lead in food and water samples.

A fast and simple dispersive solid-phase microextraction method (d-SPμE) was described for the determination of copper and lead in food, water, and sediments using FAAS. Firstly, nanoflower Al2O3@carbon spheres composite (NF Al2O3@CSs) was synthesized and then characterized. The obtained NF Al2O3@CSs was used for the d-SPμE of copper and lead in aqueous solutions. The influence of important parameters like pH, contact time, eluent conditions, volume of sample, and competing ion effects on the d-SPμE efficiency of copper and lead was investigated. They were pH, 7; eluent, 2 mol L-1 HCl (2 mL); sample volume, 250 mL for copper and 150 mL for lead with recoveries ≥90%. The adsorption and elution of analytes on NF Al2O3@CSs were realized quickly without vortexing. The LODs of the d-SPμE for copper and lead were found to be 0.69 μg L-1 and 2.8 μg L-1, respectively, while its PF was 125 for copper and 75 for lead. The intra-day precision and inter-day repeatability (RSD%, n = 7) were 1.3% and 1.6% for Cu(II) and 2.3% and 3.2% for Pb(II), respectively. Finally, the accuracy of the d-SPμE was investigated by determination of the analytes in four certified reference materials (TMDA-53.3 Lake water, NW-TMDA-54.6 Lake water, NIST 1573a Tomato leaves, and NIST RM 8704 Buffalo River Sediment). The analyte recoveries together with analyses of dam water, river water, wastewater, sea water, sumac, tea, chocolate, and lentils were studied. The results indicate that recoveries ranged from 90 to 103% in water samples and 91 to 110% in food samples.

Effects of freeze–thaw cycling on metal-phosphate formation and stability in single and multi-metal systems

Freeze–thaw cycling may influence the chemistry, mineral stability and reaction rate during metal orthophosphate fixation. This study assessed the formation and stability of Cu-, Pb-, and Zn-phosphates in chemically simple laboratory systems during 240 freeze–thaw cycles (120 days) from +10 to −20 °C, using X-ray diffractometry. In single heavy metal systems, chloro- and hydroxy-pyromorphite (Pb5(PO4)3(Cl,OH)), sodalite (Na6Zn6(PO4)6·8H2O), chiral zincophosphate (Na12(Zn12P12O48)·12H2O), and copper phosphate hydrate (Cu3(PO4)2·3H2O) were the primary phosphate minerals that formed, and were typically stable during the experiment. Zinc and Cu-phosphate formation was reduced in multi heavy metal systems, and was substantially lower in abundance than chloropyromorphite. Successful Cu-, Pb- and Zn-phosphate formation can be expected in cold and freezing environments like the polar regions. However, field implementation of orthophosphate fixation needs to consider competing ion effects, concentration of the phosphate source, and the amount of free-water.

As(III) and As(V) Adsorption by Hydrous Zirconium Oxide Nanoparticles Synthesized by a Hydrothermal Process Followed with Heat Treatment

Hydrous zirconium oxide (ZrO2·xH2O) were synthesized by a low-cost hydrothermal process followed with heat treatment. ZrO2·xH2O nanoparticles ranged from 6 nm to 10 nm and formed highly porous aggregates, resulting in a large surface area of 161.8 m2 g–1. The batch tests on the laboratory water samples demonstrated a very high degree of As(III) and As(V) removal by ZrO2·xH2O nanoparticles. The adsorption mechanism study demonstrated that both arsenic species form inner-sphere surface complexes on the surface of ZrO2·xH2O nanoparticles. Higher arsenic removal effect of these ZrO2·xH2O nanoparticles were demonstrated, compared with commercially available Al2O3 and TiO2 nanoparticles. Ionic strength and competing ion effects on the arsenic adsorption of these ZrO2·xH2O nanoparticles were also studied. Testing with natural lake water confirmed the effectiveness of ZrO2·xH2O nanoparticles in removing arsenic species from natural water, and the immobilization of ZrO2•xH2O nanoparticles on glass fiber cloth minimized the dispersion of nanoparticles into the treated body of water. The high adsorption capacity of ZrO2·xH2O nanoparticles is shown to result from the strong inner-sphere surface complexing promoted by the high surface area, large pore volume, and surface hydroxyl groups of zirconium oxide nanoparticles.

Iron and manganese amended activated alumina – a medium for adsorption/oxidation of arsenic from water

Research Article| February 01 2007 Iron and manganese amended activated alumina – a medium for adsorption/oxidation of arsenic from water Anuj Kumar Dhiman; Anuj Kumar Dhiman 1Kaveri Infrastructure (P) Ltd, Kaveri House, B-5, Geetanjali Enclave, Malviya Nagar, New Delhi 110017, India Search for other works by this author on: This Site PubMed Google Scholar Malay Chaudhuri Malay Chaudhuri 2Civil Engineering Programme, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan, Malaysia Tel.: +60 5 368 7286 Fax: +60 5 365 6716 E-mail: malaychaudhuri@yahoo.com; malay@iitk.ac.in Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2007) 56 (1): 69–74. https://doi.org/10.2166/aqua.2007.061 Article history Received: January 30 2006 Accepted: July 10 2006 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Anuj Kumar Dhiman, Malay Chaudhuri; Iron and manganese amended activated alumina – a medium for adsorption/oxidation of arsenic from water. Journal of Water Supply: Research and Technology-Aqua 1 February 2007; 56 (1): 69–74. doi: https://doi.org/10.2166/aqua.2007.061 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex In a laboratory study, iron and manganese amended activated alumina (IMAA) showed promise as an effective medium for removing arsenic [As(III) and As(V)] from groundwater. Batch adsorption/oxidation kinetic test indicated that the effectiveness of the IMAA medium was due to in situ oxidation of As(III) to As(V) and higher adsorption of As(V) by the medium. A home arsenic removal unit, containing 4 L of IMAA or AA and operated at 6 L/h, produced 2400 L and 2340 L or 1392 L and 1320 L of water in two cycles of runs when the influent arsenic concentration was 1.0 mg/L [0.6 mg/L of As(III) and 0.4 mg/L of As(V)]. The IMAA medium should be subjected to field trials to assess the long-term effects on performance, such as loss of medium capacity, attrition of the iron and manganese coating, fouling by organics, and pH and competing ion effects. activated alumina, adsorption/oxidation, arsenic removal, iron, manganese This content is only available as a PDF. © IWA Publishing 2007 You do not currently have access to this content.

A study of the competing ion effects in the biosorption of metals

Bacterial dissimilatory reduction of iron and sulphur in extremely acidic environments is described. Evidence for reduction at two disused mine sites is presented, within stratified 'acid streamers' growths and in sediments from an acid mine drainage stream. A high proportion (approx. 40%) of mesophilic heterotrophic acidophiles were found to be capable of reducing ferric iron (soluble and insoluble forms) under microaerophilic and anoxic conditions. Mixed cultures of Thiobacillus ferrooxidans and Acidiphilium-like isolate SJH displayed cycling of iron in shake flask and fermenter cultures. Oxido-reduction of iron in mixed cultures was determined by oxygen concentration and availability of organic substrates. Some moderately thermophilic iron-oxidis- ing bacteria were also shown to be capable of reducing ferric iron under conditions of limiting oxygen when grown in glycerol/yeast extract or elemental sulphur media. Cycling of iron was observed in pure cultures of these acidophiles. Sulphate-reducing bacteria isolated from acid streamers could be grown in acidified glycerol/yeast extract media (as low as pH 2.9), but not in media used conventionally for their laboratory culture. An endospore-forming, non-motile rod resembling Desulfotomaculum has been isolated. This bacterium has a wide pH spectrum, and appears to be acid-tolerant rather than acidophilic.

Electrical Conductivity used for Evaluation of Competing Ion Effects on Radionuclide Uptake by Plant Roots

Although competing ion concentration is one of the sensitive factors affecting radionuclide transfer in a soil-to-crop pathway, continuous measurement of each ion concentration is now difficult in an actual field. In this study, using electrical conductivity (EC) was proposed as an alternative of ion concentration for evaluating the competing effect on uptake of cationic radionuclides (54Mn, 60Co, 65Zn, 85Sr, 137Cs) by a leafy plant (Brassica campestris). Linear relationships in the logarithmic graph were found between the selective absorption coefficients and the solution ECs. For 137Cs, the competing effect was found to be relatively small. Because of its easiness and quickness in measurement, the EC is expected to be effectively applied to prediction of changes in soil-to-plant transfer of selected radionuclides where the soil salinity varies in time and spatial scale.