Removal of chromium from water using manganese (II, III) oxides coated sand: adsorption and transformation of Cr(VI) and Cr(III).

A manganese coated sand (MCS) sorbent containing manganese (II,III) oxides was developed for adsorption and transformation of chromium [Cr(VI) and Cr(III)] with potential application in flow-through permeable media adsorption filters. Characterization of the MCS sorbent using XRD and XPS showed that the oxides of manganese (II) and manganese (III) were present on the MCS sorbent surface. Adsorption of both Cr(VI) and Cr(III) onto the MCS sorbent occurred over a broad pH range from 3 to 10.

Adsorption of hexavalent chromium from water using manganese-aluminum coated sand: Kinetics, equilibrium, effect of pH and ionic strength.

Removal of hexavalent chromium [Cr(VI)] from water was evaluated using a low-cost coated sand adsorbent for potential application in a flow-through filter system using permeable adsorption media. Manganese-aluminum coated sand (MACS) was investigated as a hybrid metal oxide based adsorbent due to the potential efficacy of manganese oxide and aluminum oxide for adsorption of Cr(VI) from water. Adsorbent characterization was performed using XRD, SEM/EDX, XPS and BET.

Removal of arsenic from water using manganese (III) oxide: Adsorption of As(III) and As(V).

Removal of arsenic from water was evaluated with manganese (III) oxide (Mn2O3) as adsorbent. Adsorption of As(III) and As(V) onto Mn2O3 was favorable according to the Langmuir and Freundlich adsorption equilibrium equations, while chemisorption of arsenic occurred according to the Dubinin-Radushkevich equation. Adsorption parameters from the Langmuir, Freundlich, and Temkin equations showed a greater adsorption and removal of As(III) than As(V) by Mn2O3.

Groundwater arsenic in Chimaltenango, Guatemala.

In the Municipality of Chimaltenango, Guatemala, we sampled groundwater for total inorganic arsenic. In total, 42 samples were collected from 27 (43.5%) of the 62 wells in the municipality, with sites chosen to achieve spatial representation throughout the municipality.

Adsorption and removal of arsenic (V) using crystalline manganese (II,III) oxide: Kinetics, equilibrium, effect of pH and ionic strength.

Manganese (II,III) oxide (Mn3O4) crystalline powder was evaluated as a potential sorbent for removal of arsenic (V) from water. Adsorption isotherm experiments were carried out to determine the adsorption capacity using de-ionized (DI) water, a synthetic solution containing bicarbonate alkalinity, and two natual groundwater samples. Adsorption isotherm data followed the Langmuir and Freundlich equations, indicating favorable adsorption of arsenic (V) onto Mn3O4, while results from the Dubinin-Radushkevich equation were suggestive of chemisorption of arsenic (V).

Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities.

The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.

Adsorption of fluoride onto crystalline titanium dioxide: effect of pH, ionic strength, and co-existing ions.

Adsorption of fluoride from water onto titanium dioxide (TiO(2)) powder was investigated. The sorbent was crystalline TiO(2) composed of mostly anatase with a specific surface area of 56 m(2)/g. Adsorption kinetics and isotherm experiments were performed using an aqueous solution with bicarbonate alkalinity representative of natural waters.

Deposition and release kinetics of nano-TiO2 in saturated porous media: effects of solution ionic strength and surfactants.

The aggregation, transport and deposition kinetics (i.e. attachment and release) of TiO(2) nanoparticles (nano-TiO(2)) were investigated as a function of ionic strength and the presence of anionic (sodium dodecylbenzene sulfonate, SDBS) and non-ionic (Triton X-100) surfactants in 100% critical micelle concentration (CMC).

Effect of biostimulation on the microbial community in PCB-contaminated sediments through periodic amendment of sediment with iron.

Reductive dehalogenation of polychlorinated biphenyls (PCBs) by indigenous dehalorespiring microorganisms in contaminated sediments may be enhanced via biostimulation by supplying hydrogen generated through the anaerobic corrosion of elemental iron added to the sediment. In this study, the effect of periodic amendment of sediment with various dosages of iron on the microbial community present in sediment was investigated using phospholipid fatty acid analysis (PLFA) over a period of 18 months. Three PCB-contaminated sediments (two freshwater lake sediments and one marine sediment) were used.

Reactivity of lactate-modified nanoscale iron particles with 2,4-dinitrotoluene in soils.

This paper investigates the reactivity of nanoscale iron particles (NIP) and lactate-modified NIP (LM-NIP) with 2,4-dinitrotoluene (2,4-DNT), a representative munitions contaminant, in kaolin and field sand as representative low and high permeability soils, respectively. Aluminum lactate, a green compound, was selected as the modifier based on earlier studies which showed it to be an effective dispersant for enhanced transport of NIP in soils. Kaolin and sand were spiked at concentration of 920 and 740 mg/kg of DNT.

Extraction of pentachlorophenol from soils using environmentally benign lactic acid solutions.

Soil contamination with pentachlorophenol (PCP) is widespread across the globe. Soil washing/extraction is a common technique to remove this compound. Several soil washing/extraction solutions have been used but a majority of them have the problem of persistence in the environment due to their low biodegradability.

Preliminary assessment of imidazolium-based room-temperature ionic liquids for extraction of organic contaminants from soils.

Alternative solvents known as room-temperature ionic liquids (RTILs) were considered for extraction of organic soil contaminants. A hydrophobic RTIL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim]PF6), and a hydrophilic RTIL, 1-butyl-3-methyl imidazolium chloride ([bmim]Cl), were selected as representative imidazolium-based RTILs to assess the extraction of several organic contaminants (OCs) from two model soils. The two soils were montmorillonite (clay minerals, high surface area, and no organic matter) and glacial till (organic matter).

Electroosmotic dewatering of dredged sediments: bench-scale investigation.

The Indiana Harbor (Indiana, USA) has not been dredged since 1972 due to lack of a suitable disposal site for dredged sediment. As a result of this, over a million cubic yards of highly contaminated sediment has accumulated in the harbor. Recently, the United States Army Corps of Engineers (USACE) has selected a site for the confined disposal facility (CDF) and is in the process of designing it.

Effect of different extraction agents on metal and organic contaminant removal from a field soil.

This paper presents an evaluation of different extracting solutions for the removal of phenanthrene, lead and zinc from a contaminated soil obtained from a former manufactured gas plant site. The field soil contained 50%-88% sand, 11%-35% fines, 2.7%-3.

Assessing the bioavailability of PAHs in field-contaminated sediment using XAD-2 assisted desorption.

An XAD-2 assisted desorption assay was evaluated to assess its functionality in determining the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in an aged field-contaminated sediment. In the study, various dosages of XAD-2 resin were added to abiotic sediment-water slurry systems to adsorb the PAHs from the aqueous phase thus accelerating the desorbability of these contaminants from the sediment. A parallel experiment on the biodegradation of these PAHs by microorganisms indigenous to the sediment was also conducted.

Studies on bioremediation of polycyclic aromatic hydrocarbon-contaminated sediments: bioavailability, biodegradability, and toxicity issues.

The widespread contamination by polycyclic aromatic hydrocarbons (PAHs) has created a need for cost-effective bioremediation processes. This research studied a chronically PAH-contaminated estuarine sediment from the East River (ER; NY, USA) characterized by high concentrations of PAHs (approximately 4-190 ppm), sulfide, and metals and a marine sediment from New York/ New Jersey Harbor (NY/NJH; USA) with only trace quantities of PAHs (0.1-0.