Sustainable application of surfactants in soil remediation: Selective pollutants adsorption and hydrogen peroxide-driven adsorbent regeneration.

The uncontrolled disposal of the liquid lindane wastes have led to the formation of dense non-aqueous phase liquids (DNAPL), consisting of 28 chlorinated organic compounds (COCs), contaminating soil and groundwater. Surfactant-enhanced aquifer remediation is proposed as technology to treat these sites. However, the polluted emulsion generated must be manged on-site.

Treatment of a Complex Emulsion of a Surfactant with Chlorinated Organic Compounds from Lindane Wastes under Alkaline Conditions by Air Stripping.

Surfactant-enhanced aquifer remediation is commonly applied in polluted sites with dense non-aqueous phase liquids (DNAPLs). This technique transfers the contamination from subsoil to an extracted emulsion, which requires further treatment. This work investigated the treatment of a complex emulsion composed of a nonionic surfactant and real DNAPL formed of chlorinated organic compounds (COCs) and generated as a lindane production waste by air stripping under alkaline conditions.

Non-Ionic Surfactant Recovery in Surfactant Enhancement Aquifer Remediation Effluent with Chlorobenzenes by Semivolatile Chlorinated Organic Compounds Volatilization.

Surfactant enhanced aquifer remediation is a common treatment to remediate polluted sites with the inconvenience that the effluent generated must be treated. In this work, a complex mixture of chlorobenzene and dichlorobenzenes in a non-ionic surfactant emulsion has been carried out by volatilization. Since this techhnique is strongly affected by the presence of the surfactant, modifying the vapour pressure, Pv0, and activity coefficient, γ, a correlation between Pvj0γj and surfactant concentration and temperature was proposed for each compound, employing the Surface Response Methodology (RSM).

Abatement of chlorobenzenes in aqueous phase by persulfate activated by alkali enhanced by surfactant addition.

Sites polluted by dense non-aqueous phases (DNAPLs) constitute an environmental concern. In situ chemical oxidation (ISCO) application is limited since oxidation often occurs in the aqueous phase and contaminants are usually hydrophobic. In this work, ISCO enhanced by the surfactant addition (S-ISCO) was studied for a complex liquid mixture of chlorinated organic compounds (COCs) using persulfate (PS) activated by alkali (PSA) as oxidant and Emulse-3® as a commercial non-ionic surfactant.

Remediation of HCHs-contaminated sediments by chemical oxidation treatments.

The intensive use of organochlorine pesticides, such as lindane (γ-HCH), and the inadequate management of their wastes, is a huge environmental problem. The lindane production during the last century has generated huge volumes of solid wastes of other HCH isomers, causing hot points of soil and groundwater contamination. The soil treated in this work was obtained from a landfill located in the nearby of an old lindane factory, containing α-HCH and β-HCH as main contaminants.

Compatibility of nonionic and anionic surfactants with persulfate activated by alkali in the abatement of chlorinated organic compounds in aqueous phase.

Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) is an emerging technology in the remediation of sites with residual Dense Non-Aqueous Phase Liquids (DNAPLs), a ubiquitous problem in the environment and a challenge to solve. In this work, three nonionic surfactants: E-Mulse3® (E3), Tween80 (T80), and a mixture of Tween80-Span80 (TS80), and an anionic surfactant: sodium dodecyl sulfate (SDS), combined with persulfate activated by alkali (PSA) as oxidant have been investigated to remove the DNAPL generated as liquid waste in lindane production, which is composed of 28 chlorinated organic compounds (COCs). Because the compatibility between surfactants and oxidants is a key aspect in the S-ISCO effectiveness the unproductive consumption of PS by surfactants was investigated in batch (up to 864 h) varying the initial concentration of PS (84-42 mmol·L) and surfactants (0-12 g·L) and the NaOH:PS molar ratio (1 and 2).

Surfactant-Enhanced Solubilization of Chlorinated Organic Compounds Contained in DNAPL from Lindane Waste: Effect of Surfactant Type and pH.

Application of surfactants in the remediation of polluted sites with dense nonaqueous phase liquid (DNAPL) still requires knowledge of partitioning between surfactants and pollutants in the organic and aqueous phases and the time necessary to reach this balance. Two real DNAPLs, generated as wastes in the lindane production and taken from the polluted sites from Sabiñanigo (Spain), were used for investigating the solubilization of 28 chlorinated organic compounds (COCs) applying aqueous surfactant solutions of three nonionic surfactants (E-Mulse 3 (E3), Tween80 (T80), and a mixture of Tween80-Span80 (TS80)) and an anionic surfactant (sodium dodecyl sulfate (SDS)). The initial concentrations of surfactants were tested within the range of 3-17 g·L.

Thermally activated persulfate for the chemical oxidation of chlorinated organic compounds in groundwater.

Chlorinated pesticides were extensively produced in the XX century, generating high amounts of toxic wastes often dumped in the surroundings of the production sites, resulting in hot points of soil and groundwater pollution worldwide. This is the case of Bailín landfill, located in Sabiñánigo (Spain), where groundwater is highly polluted with chlorobenzenes (mono, di, tri and tetra) and hexachlorocyclohexanes. This study addresses the abatement of chlorinated organic compounds (COCs) present in the groundwater coming from the Bailín landfill by thermally activated persulfate, PS (TAP).

Comparison of real wastewater oxidation with Fenton/Fenton-like and persulfate activated by NaOH and Fe(II).

Treatment of polluted wastewaters from industrial activities has become a source of major concern for the environment. In this work, real wastewater from a physico-chemical (WWFQ) treatment was tested through different oxidation technologies: Fenton and Fenton-like reagent and persulfate activated by NaOH and Fe(II). Oxidation reactions with Fenton's reagent were carried out in a 0.

Partitioning of chlorinated organic compounds from dense non-aqueous phase liquids and contaminated soils from lindane production wastes to the aqueous phase.

Hexachlorocyclohexane (HCH) and mainly the γ-HCH isomer, namely lindane, were extensively produced and used as pesticides. Huge amounts of wastes, solids and liquids, were disposed of in the surroundings of the production sites. The liquid residuum was a complex mixture of chlorinated organic compounds, COCs, from chlorobenzene to heptachlorocyclohexane.

Methanol-enhanced degradation of carbon tetrachloride by alkaline activation of persulfate: Kinetic model.

Carbon tetrachloride (CT), a chlorinated organic compound widely used in the chemical industry during the 20th century, is nowadays a ubiquitous contaminant in groundwater and in situ technologies for its destruction are required. In this work, the degradation of CT by the alkaline activation of persulfate (PS) has been studied. Among the pool of radical species generated (hydroxyl radicals, sulfate radicals and superoxide radicals), O resulted to be the only species responsible for CT abatement.

Removal of lindane wastes by advanced electrochemical oxidation.

The effective removal of recalcitrant organochlorine pesticides including hexachlorocyclohexane (HCH) present in a real groundwater coming from a landfill of an old lindane (γ-HCH) factory was performed by electrochemical oxidation using a BDD anode and a carbon felt cathode. Groundwater (ΣHCHs = 0.42 mg L, TOC = 9 mg L, pH = 7, conductivity = 3.

Lindane degradation by electrooxidation process: Effect of electrode materials on oxidation and mineralization kinetics.

This study focuses on the effect of electrode materials on abatement of lindane (an organochlorine pesticide) by electrooxidation process. Comparative performances of different anodic (platinum (Pt), dimensionally stable anode (DSA) and boron-doped diamond (BDD)) and cathodic (carbon sponge (CS), carbon felt (CF) and stainless steel (SS)) materials on lindane electrooxidation and mineralization were investigated. Special attention was paid to determine the role of chlorine active species during the electrooxidation process.

Removal of organochlorine pesticides from lindane production wastes by electrochemical oxidation.

This study is focused on the effective removal of recalcitrant pollutants hexaclorocyclohexanes (HCHs, isomers α, β, γ, and δ) and chlorobenzenes (CBs) present in a real groundwater coming from a landfill of an old lindane factory. Groundwater is characterized by a total organic carbon (TOC) content of 9 mg L, pH = 7, conductivity = 3.7 mS cm, high salt concentration (SO, HCO, Cl), and ferrous iron in solution.

Phenol abatement using persulfate activated by nZVI, HO and NaOH and development of a kinetic model for alkaline activation.

Three persulfate (PS) activation methods (nanoparticles of zero-valent iron (nZVI), hydrogen peroxide and alkali) were compared using phenol as target pollutant. Firstly, four experiments were conducted at 25°C in a batch way using the same initial phenol and oxidant concentrations (10 mM and 420 mM, respectively), being the molar ratio activator/PS fixed to 0.005 with nZVI (mass ratio 0.

Use of Fenton reagent combined with humic acids for the removal of PFOA from contaminated water.

Perfluorinated compounds (PFCs) are receiving significant attention due to its global distribution, high persistence, and bioaccumulation properties. Among them, perfluorooctanoic acid (PFOA) is one of the most commonly found in the environment. The strong bond C-F in PFOA is extremely difficult to degrade, therefore advanced oxidation processes (AOPs) at room temperature and pressure are not able to oxidize them, as was noticed here using Fenton like reagent (FR) or persulfate (PS) at 25°C.

Remediation of a biodiesel blend-contaminated soil by using a modified Fenton process.

A soil contaminated with a B20 biodiesel blend (20 % biodiesel, 80 % diesel) has been treated by modified Fenton process with or without chelant addition. All experiments were conducted without pH adjustment. The reagents used were as follows: hydrogen peroxide as oxidant (400-4,000 mmol L(-1)), ferric ion as catalyst (5-20 mmol L(-1)), and trisodium citrate (50 mmol L(-1)) as chelating agent.

Essential oil from leaves of Lippia dulcis grown in Colombia.

The chemical composition of the volatile compounds from the leaves of Lippia dulcis Trev. (Verbenaceae) from Colombia was studied by GC and GC/MS. Forty volatile compounds were identified, of which the major ones were alpha-copaene (18.

In situ oxidation remediation technologies: kinetic of hydrogen peroxide decomposition on soil organic matter.

Rates of hydrogen peroxide decomposition were investigated in soils slurries. The interaction soil-hydrogen peroxide was studied using a slurry system at 20 degrees C and pH 7. To determine the role of soil organic matter (SOM) in the decomposition of hydrogen peroxide, several experiments were carried out with two soils with different SOM content (S1=15.

Chemical oxidation of 2,4-dimethylphenol in soil by heterogeneous Fenton process.

Hydrogen peroxide has been used to oxidize a sorbed aromatic contaminant in a loamy sand with 195.9 g kg(-1) of organic carbon by using iron as catalyst at 20 degrees C. The 2,4-dimethylphenol (2,4-DMP) was chosen as pollutant.

Low doses of lead: effects on reproduction and development in rats.

The effects of exposure to high doses of lead on reproduction and development have been established, but not so those caused by low lead doses or the influence that life stage at which contact with the metal takes place might have. The aim of this work was to study the effects of 200 and 400 ppm lead acetate in drinking water on reproduction and development as well as on renal and hepatic parameters of rats at different life stages, from gestation to 3 mo postweaning. The results indicate a dose-dependent effect on reproduction, with variations in the number of births and in pups' weight.

Effect of the crosslinking degree and the nickel salt load on the thermal decomposition of poly(2-hydroxyethyl methacrylate) hydrogels and on the metal release from them.

Polymeric matrices of poly(2-hydroxyethyl methacrylate) (PHEMA) crosslinked with different percentages of ethylene glycol dimethacrylate (EGDMA) as well as different loads of nickel salt were synthesized. Nickel release from the polymeric systems, and their thermal stability were analyzed. A high percentage of the nickel loaded was released, although strong interactions between the polymeric matrices and the nickel ion must be established since a total nickel release did not take place.

Effects of lead administration at low doses by different routes on rat spleens. Study of response of splenic lymphocytes and tissue lysozyme.

The aim of this study was to evaluate the effects of low doses of lead (200 ppm of PbAc(2) for 4 weeks) on rat spleens using different routes of administration. The study has been carried out at different levels: a histological evaluation has been made, and alterations of cell proliferation, B and T lymphocyte subpopulations, and CD4(+) and CD8(+) T cell subpopulations have been evaluated. Apoptosis and necrosis of lymphoid cells were also analysed.