Removal of heavy metals from industrial wastewaters using insoluble starch xanthate /

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A novel fibre-coated sorbent for rapid removal of heavy metals from wastewater. Sorption of Zinc(II) from dilute aqueous solutions in the presence of high concentrations of common salts

The commercial acrylic fibre "Cashmilon" was partially hydrolyzed to convert a fraction of its nitrile (-CN) groups to carboxylic acid (-COOH) groups and then coated with polyethylenimine (PEI) resin and cross-linked with glutaraldehyde to produce a novel gel-coated fibrous sorbent with multiple functionalities of cationic, anionic and chelating types, and significantly faster sorption kinetics than bead-form sorbents. The sorption properties of the fibrous sorbent were measured using Zn(II) in aqueous solution as the sorbate to determine the effects of pH and the presence of common ions in the solution on the sorption capacity. The rate of sorption on the gel-coated fibre was measured in comparison with that on Amberlite IRA-68 weak-base resin beads, to demonstrate the marked difference between fibre and bead-form sorbents in their kinetic behaviour.

A novel fibre-coated sorbent for rapid removal of heavy metals from wastewater. Sorption of Zinc(II) from dilute aqueous solutions in the presence of high concentrations of common salts

The commercial acrylic fibre "Cashmilon" was partially hydrolyzed to convert a fraction of its nitrile (-CN) groups to carboxylic acid (-COOH) groups and then coated with polyethylenimine (PEI) resin and cross-linked with glutaraldehyde to produce a novel gel-coated fibrous sorbent with multiple functionalities of cationic, anionic and chelating types, and significantly faster sorption kinetics than bead-form sorbents. The sorption properties of the fibrous sorbent were measured using Zn(II) in aqueous solution as the sorbate to determine the effects of pH and the presence of common ions in the solution on the sorption capacity. The rate of sorption on the gel-coated fibre was measured in comparison with that on Amberlite IRA-68 weak-base resin beads, to demonstrate the marked difference between fibre and bead-form sorbents in their kinetic behaviour.

A multi-capability sensor for hydrocarbons, synthetic-based fluids and heavy metals:Applications for environmental monitoring during removal of drill cuttings piles

As part of any drilling cuttings pile removal process the requirement for monitoring the release of contaminants into the marine environment will be critical. Traditional methods for such monitoring involve taking samples for laboratory analysis. This process is time consuming and only provides data on spot samples taken from a limited number of locations and time frames. Such processes, therefore, offer very restricted information. The need for improved marine sensors for monitoring contaminants is established. We report here the development and application of a multi-capability optical sensor for the real-time in situ monitoring of three key marine environmental and offshore/oil parameters: hydrocarbons, synthetic-based fluids and heavy metal concentrations. The use of these sensors will be a useful tool for real-time in situ environmental monitoring during the process of decommissioning offshore structures. Multi-capability array sensors could also provide information on the dispersion of contamination from drill cuttings piles either while they are in situ or during their removal.

Influence of dissolved organic matter on the solubility of heavy metals in sewage-sludge-amended soils

Sewage-sludge-amended soils generally contain elevated levels of organic matter and heavy metals compared to control soils. Because organic matter is known to complex with heavy metals, the solubility behavior of the organic matter in such soils may exert a significant influence on the solubility of the metals. Little is known about such a process. Using batch experiments in which the solubility of organic matter in a heavily sludge-amended soil was artificially manipulated, we show that the solubilities of the heavy metals copper (Cu), nickel (Ni), and lead (Pb) show a strong positive relationship to the solubility of organic matter, particularly at high pH. The results suggest that under field conditions, spatiotemporal variations in the solid-solution partitioning of organic matter may have a bearing on the environmental significance (mobility and bioavailability) of these heavy metals.

Speciation of heavy metals in sewage irrigated pastures

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The reactive surface of Castor leaf [Ricinus communis L.] powder as a green adsorbent for the removal of heavy metals from natural river water

In this study, a green adsorbent was successfully applied to remove toxic metals from aqueous solutions. Dried minced castor leaves were fractionated into 63-μm particles to perform characterization and extraction experiments. Absorption bands in FTIR (Fourier Transform Infrared Spectroscopy) spectra at 1544, 1232 and 1350 cm-1 were assigned to nitrogen-containing groups. Elemental analysis showed high nitrogen and sulfur content: 5.76 and 1.93%, respectively. The adsorption kinetics for Cd(II) and Pb(II) followed a pseudo-second-order model, and no difference between the experimental and calculated Nf values (0.094 and 0.05 mmol g-1 for Cd(II) and Pb(II), respectively) was observed. The Ns values calculated using the modified Langmuir equation, 0.340 and 0.327 mmol g-1 for Cd(II) and Pb(II), respectively, were superior to the results obtained for several materials in the literature. The method proposed in this study was applied to pre-concentrate (45-fold enrichment factor) and used to measure Cd(II) and Pb(II) in freshwater samples from the Paraná River. The method was validated through a comparative analysis with a standard reference material (1643e). © 2013 Elsevier B.V. © 2013 Elsevier B.V. All rights reserved.

Coal ash conversion into effective adsorbents for removal of heavy metals and dyes from wastewater

Fly ash was modified by hydrothermal treatment using NaOH solutions under various conditions for zeolite synthesis. The XRD patterns are presented. The results indicated that the samples obtained after treatment are much different. The XRD profiles revealed a number of new reflexes, suggesting a phase transformation probably occurred. Both heat treatment and chemical treatment increased the surface area and pore volume. It was found that zeolite P would be formed at the conditions of higher NaOH concentration and temperature. The treated fly ash was tested for adsorption of heavy metal ions and dyes in aqueous solution. It was shown that fly ash and the modified forms could effectively absorb heavy metals and methylene blue but not effectively adsorb rhodamine B. Modifying fly ash with NaOH solution would significantly enhance the adsorption capacity depending on the treatment temperature, time, and base concentration. The adsorption capacity of methylene blue would increases with pH of the dye solution and the sorption capacity of FA-NaOH could reach 5 x 10(-5) mol/g. The adsorption isotherm could be described by the Langmuir and Freundlich isotherm equations. Removal of copper and nickel ions could also be achieved on those treated fly ash. The removal efficiency for copper and nickel ions could be from 30% to 90% depending on the initial concentrations. The increase in adsorption temperature will enhance the adsorption efficiency for both heavy metals. The pseudo second-order kinetics would be better for fitting the dynamic adsorption of Cu and Ni ions. (c) 2005 Elsevier B.V. All rights reserved.

A comparative study of alginate beads and an ion-exchange resin for the removal of heavy metals from a metal plating effluent

The capacity of dry protonated calcium alginate beads to sorb metals from an industrial effluent was studied and compared with a commercial ion-exchange resin (Lewatit TP 207). Both sorbents decreased zinc, nickel, iron and calcium concentrations in the effluent, and released sodium during treatment. Alginate beads removed lower amounts of heavy metals than the resin, but exhibited faster uptake kinetics. Zinc desorption from the sorbents was achieved in 30 minutes using 0.1 M HCl or 0.1 M H(2)SO(4). Desorption ratios with these acids varied between 90 and 100% for alginate, and 98 to 100% for the ion-exchange resin. Reusability tests with HCl showed that alginate beads can stand acid desorption and recover binding capacity. Overall, the comparison of dry protonated alginate beads with the resin supports the potential of the biosorbent for the treatment of industrial effluents.

The impacts of traffic and rainfall characteristics on heavy metals build-up and wash-off from urban roads

An investigation into the effects of changes in urban traffic characteristics due to rapid urbanisation and the predicted changes in rainfall characteristics due to climate change on the build-up and wash-off of heavy metals was carried out in Gold Coast, Australia. The study sites encompassed three different urban land uses. Nine heavy metals commonly associated with traffic emissions were selected. The results were interpreted using multivariate data analysis and decision making tools, such as principal component analysis (PCA), fuzzy clustering (FC), PROMETHEE and GAIA. Initial analyses established high, low and moderate traffic scenarios as well as low, low to moderate, moderate, high and extreme rainfall scenarios for build-up and wash-off investigations. GAIA analyses established that moderate to high traffic scenarios could affect the build-up while moderate to high rainfall scenarios could affect the wash-off of heavy metals under changed conditions. However, in wash-off, metal concentrations in 1-75µm fraction were found to be independent of the changes to rainfall characteristics. In build-up, high traffic activities in commercial and industrial areas influenced the accumulation of heavy metal concentrations in particulate size range from 75 - >300 µm, whereas metal concentrations in finer size range of <1-75 µm were not affected. As practical implications, solids <1 µm and organic matter from 1 - >300 µm can be targeted for removal of Ni, Cu, Pb, Cd, Cr and Zn from build-up whilst organic matter from <1 - >300 µm can be targeted for removal of Cd, Cr, Pb and Ni from wash-off. Cu and Zn need to be removed as free ions from most fractions in wash-off.

Influence of physical and chemical parameters on the treatment of heavy metals in polluted stormwater using zeolite : A review

Zeolite-based technology can provide a cost effective solution for stormwater treatment for the removal of toxic heavy metals under increasing demand of safe water from alternative sources. This paper reviews the currently available knowledge relating to the effect of properties of zeolites such as pore size, surface area and Si:Al ratio and the physico-chemical conditions of the system such as pH, temperature, initial metal concentration and zeolite concentration on heavy metal removal performance. The primary aims are, to consolidate available knowledge and identify knowledge gaps. It was established that an in-depth understanding of operational issues such as, diffusion of metal ions into the zeolite pore structure, pore clogging, zeolite surface coverage by particulates in stormwater as well as the effect of pH on stormwater quality in the presence of zeolites is essential for developing a zeolite-based technology for the treatment of polluted stormwater. The optimum zeolite concentration to treat typical volumes of stormwater and initial heavy metal concentrations in stormwater should also be considered as operational issues in this regard. Additionally, leaching of aluminium and sodium ions from the zeolite structure to solution were identified as key issues requiring further research in the effort to develop cost effective solutions for the removal of heavy metals from stormwater.

Concentration and distribution of heavy metals (lead, cadmium, chromium, copper, nickel, zinc) in Karachi shore and offshore sediments

A study to measure the heavy metal pollution level in the sediment of coastal and offshore area indicates that high concentration of heavy metals were found around Manora channel and eastern coast of Karachi. In comparison with coastal areas, relatively low concentration of heavy metals was recorded in the offshore area. The result shows that sewage and industrial wastes are the main source of heavy metal pollution in the coastal area. The concentration of heavy metals in the sediments is as follows: Chromium 10.4-33.69, nickel 13.3-47.6, lead 10.0-39.04, cadmium 0.08-0.21, zinc 7.4-73.2 and copper 9.44-18.56 mg/kg. In the offshore areas strong correlation was observed between copper and organic carbon, and calcium carbonate and cadmium. In the shore area such correlation has been recorded among nickel, chromium, zinc, and chromium and copper. The Karachi. coast is viewed as moderately polluted when compared to other continental coastal areas.

Heavy metals in certain commercially important finfish off Mahim in Mumbai coastal waters

The coastal water of the metropolitan city of Mumbai has deteriorated due to the indiscriminate discharge of untreated sewage and industrial waste in huge quantities. Mahim creek is one such locality surrounded by a large number of industrial units discharging heavy metals. The accumulation of the heavy metals Cu, Cd, Zn and Pb in finfishes (Coilia dussumeri, Lepturacanthus savala, Harpodon nehereus and Johnieops elongates) from this locality along with that in the sediment was studied. The rate of accumulation of Cu was high compared to Cd, Zn and Pb. A gradual increase in the bioaccumulation of heavy metals was noticed in fishes with increase in average body weight and length, perhaps due to biomagnification. A declining trend in concentration of heavy metals horizontally from inshore to offshore was observed in these fishes.

Heavy metals in plants and phytoremediation - A state-of-the-art report with special reference to literature published in Chinese journals

Goal, Scope and Background. In some cases, soil, water and food are heavily polluted by heavy metals in China. To use plants to remediate heavy metal pollution would be an effective technique in pollution control. The accumulation of heavy metals in plants and the role of plants in removing pollutants should be understood in order to implement phytoremediation, which makes use of plants to extract, transfer and stabilize heavy metals from soil and water. Methods. The information has been compiled from Chinese publications stemming mostly from the last decade, to show the research results on heavy metals in plants and the role of plants in controlling heavy metal pollution, and to provide a general outlook of phytoremediation in China. Related references from scientific journals and university journals are searched and summarized in sections concerning the accumulation of heavy metals in plants, plants for heavy metal purification and phytoremediation techniques. Results and Discussion. Plants can take up heavy metals by their roots, or even via their stems and leaves, and accumulate them in their organs. Plants take up elements selectively. Accumulation and distribution of heavy metals in the plant depends on the plant species, element species, chemical and bioavailiability, redox, pH, cation exchange capacity, dissolved oxygen, temperature and secretion of roots. Plants are employed in the decontamination of heavy metals from polluted water and have demonstrated high performances in treating mineral tailing water and industrial effluents. The purification capacity of heavy metals by plants are affected by several factors, such as the concentration of the heavy metals, species of elements, plant species, exposure duration, temperature and pH. Conclusions. Phytoremediation, which makes use of vegetation to remove, detoxify, or stabilize persistent pollutants, is a green and environmentally-friendly tool for cleaning polluted soil and water. The advantage of high biomass productive and easy disposal makes plants most useful to remediate heavy metals on site. Recommendations and Outlook. Based on knowledge of the heavy metal accumulation in plants, it is possible to select those species of crops and pasturage herbs, which accumulate fewer heavy metals, for food cultivation and fodder for animals; and to select those hyperaccumulation species for extracting heavy metals from soil and water. Studies on the mechanisms and application of hyperaccumulation are necessary in China for developing phytoremediation.