Kinetics and mechanism on discoloration of an azo dye, methyl orange (MO), by heterogeneous Fenton-like reaction using natural schorl as catalyst were investigated in this study. Among the three kinetic models (the first-order, the second-order, and the Behnajady-Modirshahla-Ghanbery (BMG)), the BMG kinetic model was the best one to describe MO discoloration at different reaction conditions, due to its highest determination coefficients. The BMG model parameter, 1/m, increased with initial hydrogen peroxide (H2O 2) concentration, and schorl dosage and reaction temperature increased while the pH solution decreased. The phenomenon indicated that the initial MO discoloration rate increased with the ascending of the initial H 2O2 concentration, schorl dosage, and reaction temperature and the descending of the pH solution. Meanwhile, another BMG parameter, 1/b, except for the one at pH=5, were all around 1, implying that the schorl-catalyzed Fenton-like reaction had high capacity for MO discoloration. The possible reason for these phenomena was interpreted from the point of view of OH generation and Fe dissolution. Generally speaking, the amount of hydroxyl radicals increased with initial H2O2 concentration, increased schorl dosage and reaction temperature, and decreased pH solution, playing an important role in the change of 1/m values. The concentration of soluble iron ions at all adopted experimental conditions ranged from 0.23 to 1.14 mg/L, much lower than the European Union directive (2 mg/L), which demonstrated that natural schorl would be a promising heterogeneous catalyst for the Fenton-like reaction. Finally, a possible mechanism for this process was put forward. © Springer Science+Business Media Dordrecht 2013.

Soil is one of the compartments most affected by the accumulation of pollutants from anthropic sources. The present study allowed the identification of the sensitivity of the Allium cepa test system to evaluate solubilized soils from two points in the area contaminated by heavy metals, as well as a point of reference. They are all located in the municipality of Triunfo, state of Rio Grande do Sul, Brazil. The parameters used for evaluation were germination index, mitotic index, chromosomal aberrations (CA), and index of mutagenicity index (IMUT) presented by A. cepa. Significant responses of CA were observed in the two samples of contaminated soil, but IMUT was significant only for soil 3. The toxicity and cytotoxicity indexes did not show significant responses. The results indicate that the A. cepa plant test system was sensitive to investigate the genotoxicity of the soil samples and can be used as an alert in studies on soil contamination. It was partially concordant with the mutagenic responses already detected for the Salmonella/microsome assay in previous studies.

The impacts of dissolved organic matter (DOM) on the removal of 17β-estradiol (E2) in horseradish peroxidase (HRP)-mediated oxidative coupling systems were investigated in this study. The results showed that the removal rate of E2 and the affinity of HRP to E2 had been significantly decreased in the presence of DOM. Compared with urban sludge DOM (USDOM), river sediment DOM (RSDOM), which features relatively low aromaticity and molecular weight and a large number of O-containing groups, more strongly inhibited the E2–HRP–H₂O₂ reactions than USDOM. The products were analyzed with electrospray ionization mass spectrometry. The results suggested that the self-coupling of E2 was suppressed in the presence of DOM, likely resulting from cross-coupling between DOM and E2 or self-coupling of DOM in the HRP system. The results are useful in understanding the fate of estrogens in natural systems.

Perfluorooctane sulfonate (PFOS), which has numerous uses besides being an ingredient in the formulation of aqueous film-forming foams, is considered as an emerging pollutant of increasing public health and environmental concern due to recent reports of its worldwide distribution, environmental persistence and bioaccumulation potential. In an attempt to recommend a 'risk-based' remediation strategy, this study investigates the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent (MatCARE™, patent number 2009905953). Batch adsorption tests demonstrated a much faster adsorption kinetics (only 60 min to reach equilibrium) and remarkably higher PFOS adsorption capacity (0.09 mmol g-1) of the MatCARE™ compared to a commercial activated carbon (0.07 mmol g -1). Treatability studies, performed by treating the PFOS-contaminated soils with the MatCARE™ (10 % w/w) and then incubating at 25 and 37 C temperatures maintaining 60 % of the maximum water holding capacity of the soils for a period of a year, demonstrated a negligible release (water extractable) of the contaminant (only 0.5 to 0.6 %). The fixation of PFOS in soils by the new adsorbent was exothermic in nature. Soils with higher clay and organic matter content, but lower pH values, retained PFOS to a much greater extent. A cost analyses confirmed that the MatCARETM could be an economically viable option for the 'risk-based' remediation of PFOS in contaminated waters and soils. © 2013 Springer Science+Business Media Dordrecht.

The aim of this study was to develop (1) a method for the calculation of the maximum legal rate at which meat and bone meal (MBM) and biosolids should be applied to land, which took into account the soil phosphorus (P) index, the dry solids and the nutrient and metal content of each material, and (2) a quick method to evaluate their impact, when applied at the estimated maximum and twice the maximum application rates, on the release of P and metals to surface runoff. Three types of biosolids—lime stabilised (LS), anaerobically digested (AD) and thermally dried (TD)—and two types of MBM (low and high ash) were examined. The nutrient and metal losses were examined using a 1-L capacity beaker, which contained an intact soil core. Treatments were applied at maximum and twice the maximum legal application rates and then overlain with 500 mL of water, which was stirred to simulate overland flow. At the maximum legal application rate, low ash MBM (1.14 mg L⁻¹) and TD biosolids (2.43 mg L⁻¹) had the highest losses of P. Thermally dried biosolids and LS biosolids exceeded maximum allowable concentrations (MAC) for manganese, but all treatments remained below the MAC for copper and iron, at the maximum legal application rate. Anaerobically digested biosolids and high and low ash MBM would appear to have potential for landspreading, but these results are indicative only and should be verified at field scale.

The work reported here demonstrates that zero valent iron (ZVI), a material used in permeable reactive barriers, yields degradation rate constants for trichloroethylene (TCE) that are considerably different depending on whether they are determined in deionised water or in groundwater. Batch studies using ZVI and TCE-spiked deionised (DI) water and TCE-contaminated groundwater revealed that within 50 h, 80 % of the TCE present in groundwater was mineralised, compared to TCE-spiked deionised water in which only 50 % of TCE was demineralised by ZVI in 50 h. In both TCE-spiked groundwater and DI water, cis-dichloroethylene was the major by-product, and it was reduced together with TCE after 96 h of treatment. Along with changes in concentrations of TCE and its metabolites, increased levels of chloride confirmed TCE degradation. TCE-spiked groundwater gave a higher rate constant (k) under similar conditions. The elevated chloride (830 mg/l) concentrations of the groundwater could be a possible reason for this higher rate constant, in spite of the fact that groundwater also contains higher inorganic carbon (132 mg/l) and calcium (26 mg/l) and has a pH of 7.9. The rate constant (0.017-0.03223 h-1) and half-life of TCE (21.5 to 40 h) are within the reported ranges in the literature. The implications of the results for the performance of ZVI in permeable reactive barriers are that not only groundwater chemistry, but also groundwater flow conditions, plays a key role in TCE degradation. © 2013 Springer Science+Business Media Dordrecht.

Filtered total mercury (FTHg) concentrations in a rapidly urbanizing area ranged from 50 to 250 ng/L in surface waters of the Squankum Branch, a tributary to a major river (Great Egg Harbor River (GEHR)) traversing both urban and forested/wetland areas in the Coastal Plain of New Jersey. An unsewered residential area with Hg-contaminated well water (one of many in the region) is adjacent to the stream’s left bank. Although the region’s groundwater contains total Hg (THg) at background levels of <10 ng/L, water from about 700 domestic wells in urbanized areas completed in the acidic, quartzose unconfined aquifer typically at depths 20 to 30 m below land surface has been found to exceed 2,000 ng/L (the USEPA maximum contaminant level). Within urbanized areas, THg concentrations in shallow groundwater (<20 m below land surface at or near the water table) and the potential for Hg transport were not well known, representing a considerable knowledge gap. Sampling of streamwater in, and groundwater discharge to, the Squankum Branch watershed revealed that concentrations of THg generally were in the range of 1 to 10 ng/L, but narrow plumes (“plumelets”) of shallow groundwater discharging to the stream from the opposing banks contained FTHg at a concentration > 5,000 ng/L (left bank) and nearly 2,000 ng/L (right bank). The Hg content of bankside soils and sediments was high (up to 12 mg/kg) and mostly acid leachable where groundwater with high Hg concentrations discharged, indicating contributions of Hg by both runoff and shallow groundwater. Elevated concentrations of nutrients and chloride in some groundwater plumelets likely indicated inputs from septic-system effluent and (or) fertilizer applications. The Hg probably derives mainly from mercurial pesticide applications to the former agricultural land being urbanized. The study results show that soil disturbance and introduction of anthropogenic substances can mobilize Hg from soils to shallow groundwater and the Hg contamination travels in narrow plumelets to discharge points such as stream tributaries. In the entire GEHR watershed, THg concentrations in groundwater discharging to streams in urban areas tended to be higher than concentrations in water discharging to streams of forested areas, consistent with the results from this small watershed. Other areas with similar quartzose coastal aquifers, land-use history, and hydrogeology may be similarly vulnerable to Hg contamination of shallow groundwater and associated surface water.

Adsorption by low-cost adsorbents and biosorbents is recognized as an effective and economic method for low-concentration heavy metal. The purpose of this study was to investigate the possibility of the utilization of N,N′-bis(2, 5-dihydroxybenzylidene)-1, 4-diaminobenzene (DHDB)-immobilized sporopollenin (Schiff base-immobilized sporopollenin, Sp-DHDB) as a sorbent for removal of lead (II) ion from aqueous solution. The effects of different parameters (such as sorbate concentration, sorbent dosage, and pH of the medium) were investigated by differential pulse anodic stripping voltammetry (DPASV) technique. The experimental data were analyzed by the Freundlich, Langmuir, and Dubinin–Radushkevich (D–R) isotherms. Equilibrium data fitted well with the Freundlich model and the procedure developed was successfully applied for the removal of lead ions in aqueous solutions. This investigation reveals a new, simple, environmentally friendly, and cost-effective method for the removal of lead ions from aqueous solutions by a new Sp-DHDB material.

The processes affecting adsorption of molybdenum (Mo) in alkaline industrial soils are not well known, as most research on Mo fate and transport has focused on agricultural soils. In this work, we performed studies of soil extraction, as well as sorption studies using both batch and stirred-flow cell approaches. After 60 h of extraction, we observed, even where three extractable fractions were present, 14.1 % of the bound residue was extracted by CaCl 2 solution. This indicates that the procedures recommended by the Commission of European Communities Bureau of Reference, which is targeted to metals cations, not anions due to the use of extractants at acidic pH, are not a suitable approach for assessing mobility and availability of Mo in alkaline soils. Because the observed extent of Mo adsorption onto two Fe minerals, goethite, and amorphous iron hydroxide (HFO) was 2 to 3 orders of magnitude higher than that onto the soil, soils amended with these Fe minerals were found to have a higher Mo adsorption capacity, with HFO yielding stronger sorption than goethite. The additivity principle was successfully used to predict Mo adsorption with the HFO-amended soil but failed to do so for the goethite-amended soil. The best fit sorption isotherms and estimated parameters were slightly different from batch and flow cell experiments. The Kd values of sorption coefficient in our industrial soils and Fe-minerals-amended soils ranged from 0.19 to 1.45 L/kg from both experimental approaches; this low adsorption potential renders it infeasible to immobilize Mo into the soilmatrix and reduce Mo availability by amending the soil with Fe minerals. In the future, materials with potentially high Mo adsorption capacities should be identified, screened, and characterized for permeable reactive barriers application. © Springer Science+Business Media Dordrecht 2013.

Textile dye Victoria Blue-B (VB-B) was approached in two different ways: one to get rid of the color for its easy disposal to the environment, and the other is to reuse the decolorized water for coloring the same dye. Shewanella decolorationis (MBTD16) isolated from Dona Paula Bay, identified by 16S rRNA gene and its action over decolorization was monitored by Fourier transform infrared spectroscopy, UV–Vis spectrum, and a color scanner. Dye removal index increased L*, a*, and b* to 91.585, −2.856, and −0.132 against 62.29, −4.93, and −20.75 within 42 h as a first report. A maximum extent of decolorization (94.83 %) could be achieved with minimum dye concentration of 50 mg L⁻¹. The colored water treated by free and immobilized bacterial cells tested to reuse (VB-B dye) could give 35–50 % more color than the original. Process parameters optimized to achieve maximum decolorization indicated pH 7, temperature 32 ± 2 °C, inoculum size 8 % with co-substrates of glucose and yeast extract 5 g L⁻¹ for its supremacy. Synthesis of lignin peroxidase and tyrosinase augmented in strain S. decolorationis only after being exposed into the dye signifies the enzymes in decolorization, and it was confirmed through one-way ANOVA. Results obtain by this work could suggest that S. decolorationis can be used very well to decolorize the textile dye, and the same water could be recycled to get back its original color by adding around half the quantity of dye. Thus, by the use of water, dye and pollution levels could be minimized.