Feasibility study for the remediation of groundwater contaminated by organolead compounds

Long range correlations of the ion current in SV channels. Met3PbCl influence study

The long-range correlations within the current signal time series of the Beta vulgaris vacuolar membrane under the influence of organolead compound (Met3PbCl) are investigated. The current time series is transformed into a dwell time series. Then the rescaled range and detrended fluctuations analyses are used. It is shown that the presence of Met3PbCl in the solution decreases the mean value of the Hurst exponent and therefore influences the long-range correlations in ionic channel current. This observation is statistically significant. An ion channel model is built and the experimental results reconstructed and analysed.

Photocatalysis of bisphenol A by an easy-settling titania/titanate composite: Effects of water chemistry factors, degradation pathway and theoretical calculation

Bisphenol A (BPA) is a widely concerned endocrine disrupting chemical and hard to be removed through conventional wastewater treatment processes. In this study, we developed a TiO₂ decorated titanate nanotubes composite (TiO₂/TNTs) and used for photocatalytic degradation of BPA. TEM and XRD analysis show that the TiO₂/TNTs is a nano-composite of anatase and titanate, with anatase acting as the primary photocatalytic site and titanate as the skeleton. TiO₂/TNTs exhibited excellent photocatalytic reactivity and its easy-settling property leaded to good reusability. After 5 reuse cycles, TiO₂/TNTs also could photo-degrade 91.2% of BPA with a high rate constant (k₁) of 0.039 min^-1, which was much better than TiO₂ and TNTs. Higher pH facilitated photocatalysis due to more reactive oxygen species produced and less material aggregation. The presence of NaCl and CaCl₂ showed negligible effects on BPA degradation, but NaHCO₃ caused an inhibition effect resulting from consumption of ·OH. Humic acid inhibited degradation mainly due to blockage of the active sites of TiO₂/TNTs. Degradation pathway was well interpreted through theoretical calculation. Hydroxyl radical played the dominate role in BPA photodegradation, and the atoms of BPA with high Fukui index based on density-functional theory (DFT) calculation are the radical easy-attacking (f⁰) sites. Considering the good photocatalytic reactivity, reusability, stability and settle property, TiO₂/TNTs promises to be an efficient alternative for removal of organic compounds from wastewaters.

Ex-Situ Remediation Technologies for Environmental Pollutants: A Critical Perspective

Pollution and the global health impacts from toxic environmental pollutants are presently of great concern. At present, more than 100 million people are at risk from exposure to a plethora of toxic organic and inorganic pollutants. This review is an exploration of the ex-situ technologies for cleaning-up the contaminated soil, groundwater and air emissions, highlighting their principles, advantages, deficiencies and the knowledge gaps. Challenges and strategies for removing different types of contaminants, mainly heavy metals and priority organic pollutants, are also described.

A review of hydrological and chemical stressors in the Adige catchment and its ecological status

Quantifying the effects of multiple stressors on Alpine freshwater ecosystems is challenging, due to the lack of tailored field campaigns for the contemporaneous measurement of hydrological, chemical and ecological parameters. Conducting exhaustive field campaigns is costly and hence most of the activities so far have been performed addressing specific environmental issues. An accurate analysis of existing information is therefore useful and necessary, to identify stressors that may act in synergy and to design new field campaigns. We present an extended review of available studies and datasets concerning the hydrological, chemical and ecological status of the Adige, which is the second longest river and the third largest river basin in Italy. The most relevant stressors are discussed in the light of the information extracted from a large number of studies. The detailed analysis of these studies identified that hydrological alterations caused by hydropower production are the main source of stress for the freshwater ecosystems in the Adige catchment. However, concurrent effects with other stressors, such as the release of pollutants from waste water treatment plants or from agricultural and industrial activities, have not been explored at depth, so far. A wealth of available studies address a single stressor separately without exploring their concurrent effect. It is concluded that a combination of extended experimental field campaigns, focusing on the coupled effects of multiple stressors, and modeling activities is highly needed in order to quantify the impact of the multifaceted human pressures on freshwater ecosystems in the Adige river.

Relevance of cross-section analysis in correct diagnosis of the state of conservation of building materials as evidenced by spectroscopic imaging

In the present work the need to use cross-section analysis as a routine procedure to characterize physiochemical damage on building materials was evaluated using a combination of spectroscopic imaging techniques based on Raman spectroscopy, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). First, samples for cross-section analysis required special preparation to avoid the loss of soluble and weakly anchored compounds and thereby ensure the representativeness of the analysis. To this end, samples were dry drilled and fractured with a single blow rather than cut to avoid friction. Cross-section analysis allowed surface deposition (crusts and patinas) to be differentiated from penetrating pollution and the affected depth to be determined. Elemental and molecular distributions were obtained to establish the origin of the compounds/elements found. Moreover, establishing the depth reached by the pollutant, which depends on the material porosity, can help to determine the physicochemical form of the pollutant. Finally, SEM-EDX images allowed surface and internal cracks, as well as the causes of these physical stresses, to be identified. As a result, surface analysis alone was shown to lead to incomplete or even incorrect conclusions that can be avoided by using cross-section analysis as a routine procedure when assessing the state of conservation of building materials.

Distribution of PCDD/Fs and organometallic compounds in sewage sludge of wastewater treatment plants in China

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), organotin and organolead compounds were measured in sewage sludge samples collected from 24 wastewater treatment plants from 18 cities of 13 provinces in China. Total international toxicity equivalent (I-TEQ) values were evaluated for PCDD/Fs. The total concentration of PCDD/Fs ranged from 104.0 to 1661 pg/g dry weight (d.w.) and 2.51-75.21 pg I-TEQ/g d.w., indicating that all I-TEQs were below Chinese legislation limit value regulated for land application. The concentrations ranged from 258 to 3886, 126 to 1129, and 84-2133 ng/g as Sn d.w., for tributyltin (TBT), dibutyltin (DBT), and diphenyltin (DPhT), respectively. On the other side, organolead concentrations ranged from 85 to 668 with an average of 279 ng/g as lead. High concentrations of organolead compounds in sewage sludge indicated that the environmental impact of organolead compounds remains in China.

Degradation efficiencies of azo dye Acid Orange 7 by the interaction of heat, UV and anions with common oxidants: persulfate, peroxymonosulfate and hydrogen peroxide

In this paper, the degradation of azo dye Acid Orange 7 (AO7) by three common peroxides (persulfate (PS), peroxymonosulfate (PMS) or hydrogen peroxide (H(2)O(2))) under various activation conditions, i.e., heat (25-80 degrees C), UV light (254 nm), or anions (SO(4)(2-), NO(3)(-), CO(3)(2-), HCO(3)(-), HPO(4)(2-), and Cl(-)), was investigated. The order of AO7 degradation efficiencies by heat activation is PS>>PMS>H(2)O(2). PS oxidation activated by heat (>50 degrees C) is an effective degradation technology, while PMS and H(2)O(2) are hardly activated. When assisted by UV, peroxides could all be activated and degrade AO7 quickly. The order is PS>H(2)O(2)>PMS. We activated peroxides, for the first time, by using some anions and compared the subsequently degradation efficiencies of AO7. It was found that PMS could be activated by some anions, but PS and H(2)O(2) cannot. The activation efficiencies of PMS by SO(4)(2-) and NO(3)(-) are negligible, whereas remarkable by HCO(3)(-), HPO(4)(2-), Cl(-) and CO(3)(2-). For HCO(3)(-), HPO(4)(2-) and Cl(-), the activation efficiencies become higher with the increase of anion concentration. For CO(3)(2-), however, the activation efficiency is higher at lower concentration.

Superstatistics analysis of the ion current distribution function: Met3PbCl influence study

A novel analysis of ion current time series is proposed. It is shown that higher (second, third and fourth) statistical moments of the ion current probability distribution function (PDF) can yield new information about ion channel properties. The method is illustrated on a two-state model where the PDF of the compound states are given by normal distributions. The proposed method was applied to the analysis of the SV cation channels of vacuolar membrane of Beta vulgaris and the influence of trimethyllead chloride (Met(3)PbCl) on the ion current probability distribution. Ion currents were measured by patch-clamp technique. It was shown that Met(3)PbCl influences the variance of the open-state ion current but does not alter the PDF of the closed-state ion current. Incorporation of higher statistical moments into the standard investigation of ion channel properties is proposed.