Site Remediation

Electrokinetic decontamination and extraction have been proven to be one of the most viable, cost effective and emerging techniques in removing contaminants, especially heavy metals from soils for about last five decades. Basic concepts and an overview of the electrokinetic extraction processes and their potential applications in geotechnical and geoenvironmental engineering have been reviewed based on the literature and presented in this paper. Primarily, theoretical and laboratory experimental studies related to electroreclamation of soils are summarised in brief with basic concepts of electrokinetic processes. The paper has been divided into different sections that include history of electrokinetics, background and concepts, modelling, parameter effects, instrumentation, contaminant extraction, field applications, and summary and recommendation. Based on the review it is obvious that the field application of electrokinetic technology to remediate heavy metal contaminated soils /sediments is very limited and site specific. Additional laboratory studies and more pilot-and full-scale information from field applications are critical to the further understanding of the technology and to customize the process in different field conditions.

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The emergence of the derelict and urban flora is a result of a myriad of current economic, political, and social conditions. The combination of the two offers an opportunity to institute a performative hybrid architecture. The remediation of the site can be achieved through combining the systems of the industrial and the organism. Because urban land is no longer valued, one can use the spaces to begin to generate temporal emergent patterns. The industrial topography can be dissolved through structured derelict ecologies throughout the city

In order to gain additional insight into mercury selectivity with nanosized DMSA-[silica], we investigated a series of ligands related to DMSA, these are: monomercaptosuccinic acid; MMSA, 2-mercapto-4-methyl-5-thiazoleacetic acid; MCT, ortho-thiosalicylic acid; o-TSA and para-thiosalicylic acid; p-TSA. The MMSA chelate is structurally similar to DMSA except that it has only one thiol group. The chelates o-TSA and p-TSA each have one thiol and one carboxylic acid group. MCT includes neutral S and N atoms in close proximity to the thiolate binding site. MCT, o-TSA and p-TSA resemble each other in having equal numbers of carboxylic acid and thiol groups and formation of amide bonds with the linker on silica is expected to eliminate the carboxylate binding sites, making thiolates the only binding sites for Hg(II), Cd(II), and Pb(II) metals ions in the nano-sized; MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica]. Each of the nano-sized MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica], show a higher preference for Hg(II) over Cd(II) and Pb(II) compared to the same free chelates in solution, respectively. In addition, there are differences in the level of metal ion chelation for each functionalized silica nanoparticle. These differences in the degree of metal chelation for each functionalized silica nanoparticles surface are explained by the difference in thiolate/carboxylate ratio upon attachment to the surface and on steric reasons based on the orientation of the thiol groups on the Electronic supplementary material The online version of this article (

In order to gain additional insight into mercury selectivity with nano-sized DMSA-[silica], we investigated a series of ligands related to DMSA, these are: monomercaptosuccinic acid; MMSA, 2-mercapto-4-methyl-5-thiazoleacetic acid; MCT, ortho-thiosalicylic acid; o-TSA and para-thiosalicylic acid; p-TSA. The MMSA chelate is structurally similar to DMSA except that it has only one thiol group. The chelates o-TSA and p-TSA each have one thiol and one carboxylic acid group. MCT includes neutral S and N atoms in close proximity to the thiolate binding site. MCT, o-TSA and p-TSA resemble each other in having equal numbers of carboxylic acid and thiol groups and formation of amide bonds with the linker on silica is expected to eliminate the carboxylate binding sites, making thiolates the only binding sites for Hg(II), Cd(II), and Pb(II) metals ions in the nano-sized; MMSA-[silica], MCT-[silica], o-TSA-[silica], and p-TSA-[silica]. Each of the nano-sized MMSA-[silica], MCT-[silica], o-TSA-[...

Heavy metals are toxic for humans and the environment. Therefore it is important to limit the emission of these heavy metals in air, water and soil. An aqueous solution of sodium trimercapto-triazine, commercially supplied under the name TMT-15, is currently used for the removal of heavy metals occurring in the washing water from flue gas purification at the incineration plant of the Intercommunale Maatschappij voor Openbare Gezondheid (IMOG) located in Harelbeke (Belgium). This aqueous solution of sodium trimercapto-triazine belongs to a group of complexion agents which are expensive and a large dosage is necessary to obtain good effluent values. Therefore an optimization study for the consumption of TMT-15 and an examination for the alternative products was performed. Key performance indicators were effluent quality and chemical consumption. The optimization study was realized based on a central composite experimental design (CCD) approach performed with the Design Expert software. The amount of complexion, coagulation and flocculation agent was used as input variable in this design, while the effluent heavy metal concentrations and the corresponding metal discharge levy were used as responses that needed optimization. Preliminary jar tests were used to determine the experimental boundaries, while the Design Expert software was used to determine the optimal complexion, coagulation and flocculation agent concentration. Based on this approach a 19% reduction in chemical use could be achieved on lab scale and, because of safety precautions, a reduction of 10% was implemented in the actual plant. Further (cost) optimization of the installation was based on an alternative analysis which revealed that the same reagent supplied by a different supplier produced similar results, but was lower in cost price.

The complex formation between mercury(H) and selected sodium thiolates and corresponding thiols in dilute pyridine solution, and between silver(I) and selected organic sulfides in dilute pyridine and DMSO solutions, was investigated by electrochemical and calorimetric measurements. The stability constants and heats for the stepwise complex formation were determined, and the complex formation entropies were calculated from these. The results are in close agreement with the tendencies which have been found for the coordination behaviour of organic chalcogen ligands towards mercury(I1) and silver(I) in other solvent systems, and the solid state. Similarly, but to a lower extent, is the case of the stability of the bond to be formed and the solubility of addition compounds between organic sulfides RSR' and the above mentioned metal acceptors.

Several poly(alkylene sulfide)s have been synthesized in excellent yields from reactions of α,ω -dibromo- and/or α,ω-dichloroalkanes with sodium sulfide nonahydrate under reflux conditions. The procedure is general, simple and convenient for the production of various poly(alkylene sulfide)s and the way reaction parameters influence the properties of the polymers formed has been examined.

Several poly(alkylene sulfide)s have been synthesized in excellent yields from reactions of α,ω -dibromo- and/or α,ω-dichloroalkanes with sodium sulfide nonahydrate under reflux conditions. The procedure is general, simple and convenient for the production of various poly(alkylene sulfide)s and the way reaction parameters influence the properties of the polymers formed has been examined.

Ð2,4,6-trimercaptotriazine, trisodium salt, nonahydrate (TMT-55) is a planar C 3 symmetric compound that is used commercially to precipitate mercury and other heavy metals from waste waters and contaminated natural waters. A series of laboratory experiments and analyses were performed to evaluate the chemistry and stability of mercury trimercaptotriazine``Hg-TMT'' precipitates that result from the addition of aqueous solutions of TMT-55 to aqueous solutions of mercury(II) chloride (HgCl 2). Several Hg-TMT species exist, most of which were previously unrecognized. The leaching properties, chemistry and long-term stability of the solids are very diverse. As examples, the white and yellow varieties of Hg-TMT are often unstable in both water and air, and may release more than 6000 mg/l of mercury into distilled and deionized water leachates. Although waste waters and contaminated ground waters are likely to contain less mercury than the HgCl 2 solutions used in this study, individuals should recognize that any Hg-TMT compounds are likely to be chemically complex and perhaps unstable under aqueous or atmospheric conditions.

This paper investigated approaches to treat the polluted groundwater in selected aquifers in Kuwait, which is the most extensive and second to none in terrestrial world case history. The selected aquifers are susceptible to pollution by oil spills during the first Gulf War. Experimental sampling of polluted soils were analysed. Results showed that granulated activated carbon is very effective in removing petroleum hydrocarbons from contaminated water. A pump-and-treat remediation scheme has been suggested for the affected parts of the freshwater fields. The cost estimates indicated that a treatment process involving carbon adsorption to remove petroleum hydrocarbons, followed by reverse osmosis to remove salt was highly likely to be the most cost-effective treatment system. The current treatment design and parametric costing approach can be applied elsewhere for the role of bioremediation in the treatment of petroleum contaminated environment, hazardous effects of petroleum hydrocarbon and genetic engineering in bioremediation.

In mining operations carried out below the water table, mine area could potentially affect the surrounding. With further deepening of the mine and quarry, the drawdown can impact on water supply wells and base flow. The variation in radius of influence under confined and unconfined aquifer condition is assessed using a hypothetical case study with three operational quarry sites. Average pit-wise radius of influence (R0) for the pit mine, under unconfined and confined aquifer conditions is 963 m and 61 km, respectively, whereas effective radius (Re) for total (cumulative) excavated mine area is 1.7 and 146 km, respectively. It means that the maximum and minimum value of overall impact/influence for the unconfined aquifer lies in-between 963 m and 1.7 km. Similarly that the maximum and minimum value of overall impact/influence for the confined aquifer lies in-between 61 and 146 km. Meanwhile, Re or effective radius for total (cumulative) excavated area seems more appropriate from evaluation viewpoint due to the overlapping (superposition) concentric mining quarries. Thus, assessment of quarry-wise and total radius of influence is of importance to fulfil targeted production, economically with minimum interruptions as part of the mine planning. Moreover, it helps us to assess, monitor and regulate the impact of a mine-dewatering program in the area. Also, the pumping test is often used to estimate radius of influence; it can trigger the inflow or radius of influence. Estimate of the radius of influence using analytical equation mainly independent of discharge/abstraction from the aquifer stands as a preferred choice for the prediction of radius of influence at the quarry/mine pit. There is a strong rationale that policies should be informed by such analytical assessment because it helps us to prevent or minimize negative impacts as part of regulation and pit-mining management and are useful tools for practitioners to design economically efficient and cost-effective in situ groundwater remediation systems, to contain contaminant plumes, to evaluate the surface–subsurface water interaction and to verify numerical models.

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, Tennessee, in the USA. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified ...

Mercury(II) complexes of thiolates having the general formula [Hg(RS)Cl 2 ] − and [Hg(RS) 2 ] have been prepared and characterized by IR and NMR (1 H and 13 C) spectroscopy (RSH = 2-aminoethanethiol hydrochloride (Aet), cysteine (Cys), thiosalicylic acid (Ts) and 2-mercaptonicotinic acid (Mnt)). The spectral data suggests that the coordination of thiolates to mercury(II) occurs through the sulfur as indicated by the absence of S–H vibrations in IR and significant downfield shifts in the C–S resonance in 13 C NMR. However, in Mnt complexes, coordination through both sulfur and nitrogen is indicated. Antimicrobial activities of the complexes were evaluated by minimum inhibitory concentration and the results showed that the complexes exhibited a wide range of activities against gram-negative bacteria (E. coli, P. aeruginosa), while moderate activity was observed against a mold, P. citrinum.

Two alkaline metal derivatives of the 2,4,6-trimercaptotriazine (H 3 TMT) ligand of formulae [Na(H 2 O) 3 (H 2 TMT)] n and [K 3 (H 2 O) 6 (H 2 TMT) 3 (H 3 TMT)] n have been synthesized and structurally characterized. Both present polymeric arrangements, with the metals showing covalent linkages to the triazine ligands. The water molecules completing the coordination around the metal centers are involved in an intricate extended hydrogen bonding network in both the lattices. While the sodium center displays a roughly octahedral geometry, the potassium metals show hepta-and octa-coordination polyhedra. #

2,4,6-trimercaptotriazine, trisodium salt, nonahydrate (TMT-55) is a planar C3 symmetric compound that is used commercially to precipitate mercury and other heavy metals from waste waters and contaminated natural waters. A series of laboratory experiments and analyses were performed to evaluate the chemistry and stability of mercury trimercaptotriazine “Hg-TMT” precipitates that result from the addition of aqueous solutions of TMT-55 to

Recent studies indicate that the sodium salt of 1,3-benzenediamidoethanethiol (BDET) is both economical and effective in precipitating mercury and other heavy metals from water. Because wastewaters and contaminated natural waters may contain a variety of heavy metals, it is important to determine how different heavy metals may interact with BDET, and whether free metals may displace those that are bound. To explore this possibility, Cd-, Cu-, Pb-, Mn-, Hgand Zn-BDET were leached separately under a nitrogen purge for up to 240 h in pH 3 aqueous solutions containing 0.100 mmol of all five heavy metals. The leaching studies indicate that dissolved Hg has a strong tendency to displace Cd, Cu, Mn, Pb, and Zn from the BDET structure. r

Toxic heavy metals in air, soil, and water are global problems that are a growing threat to the environment. There are hundreds of sources of heavy metal pollution, including the coal, natural gas, paper, and chlor-alkali industries (1,2). To meet the federal and state guidelines for heavy metal discharge, companies often use chemical precipitation or chelating agents. In order to be competitive economically, many of these chelating ligands are simple, easy to obtain, and, generally offer weak bonding for heavy metals. Poor and indiscriminant metal binding often lead to unstable metal ligand complexes. Laboratory testing of three commercial reagents, TMT (Trimercaptotriazine), Thio-Red (potassium/sodium thiocarbonate), and HMP-2000 (sodium dimethyldithiocarbamate), has shown that the investigated compounds were unable to reduce independent solutions of 50.00 ppm (parts per million) cadmium, copper, ferrous, lead, or mercury to meet EPA standards (CFR, 1994). Additionally, the tested compounds displayed high leaching rates and in some cases decomposed to produce toxic substances. For this reason, a novel multidentate ligand has been developed for the safe and effective removal of heavy metals.

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, Tennessee, in the USA. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified ...

En el trópico de Quintana Roo, al igual que en el resto del país, enormes superficies de tierra han sido utilizadas como minas a cielo abierto de las cuales se extrae materiales pétreos que se utilizan en rellenos y revestimientos de carreteras y caminos.  Una vez cumplido su ciclo productivo, es frecuente que en estos sitios las empresas mineras incumplan la legislación que establece la restauración del medio ambiente.  Desde la perspectiva del desarrollo integral, las ex minas representan el sitio ideal para producir higuerilla utilizable en la pequeña empresa de generación de bioetanol y biodiesel.  Pero, para ello, se requiere contar con cimientos que contengan información sólida, tecnologías desarrolladas a la escala adecuada y métodos para producir los elementos cognoscitivos en el campo de las ciencias jurídico-sociales y económico-administrativas.  A satisfacer estos requerimientos se orienta la presente propuesta, en una de sus lineas.

Mercury(II) complexes of thiolates having the general formula [Hg(RS)Cl2]− and [Hg(RS)2] have been prepared and characterized by IR and NMR (1H and 13C) spectroscopy (RSH = 2-aminoethanethiol hydrochloride (Aet), cysteine (Cys), thiosalicylic acid (Ts) and 2-mercaptonicotinic acid (Mnt)). The spectral data suggests that the coordination of thiolates to mercury(II) occurs through the sulfur as indicated by the absence of S–H vibrations in IR and significant downfield shifts in the C–S resonance in 13C NMR. However, in Mnt complexes, coordination through both sulfur and nitrogen is indicated. Antimicrobial activities of the complexes were evaluated by minimum inhibitory concentration and the results showed that the complexes exhibited a wide range of activities against gram-negative bacteria (E. coli, P. aeruginosa), while moderate activity was observed against a mold, P. citrinum.

a b s t r a c t BDTH 2 , 1,3-benzenediamidoethanethiol (common name) and closely related derivatives were specifically designed to become insoluble after the formation of linear, covalent bonds to aqueous mercury(II). BDTH 2 (IUPAC nomenclature, N,N 0 -bis(2-mercaptoethyl)isophthalamide) emerged as the preeminent reagent for the complete precipitation of mercury from water after several years of studies with a wide range of compounds having one, two, three, and four thiol groups. BDTH 2 does not become inactive through oxidation to disulfide and can be applied to mercury-containing water as acidic, basic, and ethanolic solutions. The BDT-Hg precipitate is extremely stable and leaches low-ppm levels of mercury only under extremely acidic and basic conditions. BDTH 2 is also effective in the aqueous precipitation of other soft, divalent metals, such as copper, cadmium, lead, and the main group elements, arsenic and selenium. The insolubility of the BDT-M compounds can be attributed to the presence of strong, non-polar, covalent M-S bonding within a water-insoluble organic framework. BDTH 2 has no known biological toxicity and is being sold as a nutritional supplement under the trade name OSR-1. This review describes the chemistry, precipitation, and leaching studies of BDTH 2 with mercury.