Search results for "water pollutant"
showing 10 items of 566 documents
The chemistry of Cr(VI) adsorption on to poly(p-phenylenediamine) adsorbent
2019
Abstract Water pollution due to industrial processes has necessitated and spurred robust research into the development of adsorbent materials for remediation. Polyphenylenediamines (PPD) have attracted significant attention because of their dual cationic and redox properties. They are able to reduce Cr(VI) to Cr(III) in solution. Interrogation of the chemical processes involved in the Cr(VI) adsorption on para-PPD was primarily by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. It was confirmed that the underlying oxidation of the amino groups to imines during the reduction of Cr(VI) to Cr(III) was irreversible. This process occurred at both acidi…
EDTA excess Zn(II) back-titration in the presence of 4-(2-pyridylazo)-resorcinol indicator and naphthol green beta as inert dye for determining Cr(II…
2006
The colour changes of 4-(2-pyridylazo)-resorcinol and naphthol green beta as new screening metallochromic indicator in back-titration of EDTA excess with Zn(II) to determine Cr(III)/EDTA complex was investigated with the help of tristimulus colorimetry. Specific colour discrimination (SCD) and L*, a*, b* 1976 parameters were successfully applied to evaluate the quality of colour transition at the end-point in non-alkaline media and in the presence of Zn(II) and Ca(II) which resulted in non-interfering species at 1x10(-3) M and 2x10(-3) M, respectively. The above concentrations are comparable with those used for Cr(III). Validation of the fast and accurate reported method was performed by at…
Distribution of Cr and Pb in artificial sea water and their sorption in marine sediments: an example from experimental mesocosms
2016
The uptake of two heavy metals (chromium and lead) in sediments in experimental mesocosms under exposure to different metal concentrations was evaluated by monitoring their concentrations over time both in seawater and in sediment. Two separate experiments under laboratory-controlled conditions were carried out for the two metals. Sediments were collected from a protected natural area characterized by low anthropic influence and were placed in mesocosms that were housed in aquaria each with seawater at a different metal concentration. At pre-established time intervals, seawater and sediment samples were collected from each mesocosm for chemical analyses. Quantification of chromium and lead …
Effects of temperature on the acute toxicity of heavy metals (Cr, Cd, and Hg) to the freshwater crayfish, Procambarus clarkii (Girard).
1987
Chromium, an essential trace element for humans and animals is involved in normal carbohydrate metabolism; however, it is toxic at high concentrations. There is no evidence that cadmium and mercury are biologically essential but their toxicity for organisms is well known. Both cause toxic effects at low concentrations to most organisms, especially in combination with other environmental variables such as temperature. Lake Albufera and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic industrial residues (including heavy metals) from the many urban and waste waters in this area. In 1978, the American red crayfish Procambarus clarkii appeared in lake Albu…
Statistical characterisation of heavy metal contents inParacentrotus lividusfrom Mediterranean Sea
2014
This work focuses on the estimation of Hg, As, Cr, Ni, Cu, V, Cd and Pb by inductively coupled plasma mass spectrometry in 135 adult specimens of Paracentrotus lividus collected in different coastal areas of Sicily (Gela, Punta Secca, Ragusa (RG), Siracusa, Priolo, Catania, Messina, Milazzo, Brolo and Filicudi), in order to monitor the Mediterranean marine ecosystem by use of sea urchin as bioindicator. Moreover, the paper deals with the statistical classification of the tested samples according to the sampling area based on metal concentrations. The descriptive statistics findings were obtained and, a starting multivariate matrix was built. Data-sets were subjected to Kruskal-Wallis test t…
Removal of trivalent chromium from tannery waste waters using bone charcoal
2002
International audience; The ability of bone charcoal to remove Cr(III) from aqueous solutions by adsorption has been investigated. The adsorbent used was first characterised and then the adsorption was studied as a function of time and amount of charcoal. Tests were carried out with synthetic solutions whose Cr concentrations (500 mg L-1) were similar to those found in some effluents of Moroccan tannery industries. Cr removal efficiencies higher than 90% were obtained at pH 3.5 using 3 g of bone charcoal and a stirring time of about 30 min. Results of Cr removal by all sieved fractions of bone charcoal had shown the same interesting capabilities for Cr(III) retention. The cross interference…
Genotoxicity of citrus wastewater in prokaryotic and eukaryotic cells and efficiency of heterogeneous photocatalysis by TiO(2).
2012
Abstract The presence of (±)α-pinene, (+)β-pinene, (+)3-carene, and R-(+)limonene terpenes in wastewater of a citrus transformation factory was detected and analyzed, in a previous study, by using Solid Phase Micro-extraction (SPME) followed by GC analyses. Purpose of that research was to compare the genotoxic responses of mixtures of terpenes with the genotoxicity of the individual compounds, and the biological effects of actual wastewater. Genotoxicity was evaluated in the Salmonella reversion assay (Ames test) and in V79 cells by Comet assay. Ames tests indicated that the four single terpenes did not induce an increase of revertants frequency. On the contrary, the mixtures of terpenes ca…
Determination of pharmaceutical residues in wastewater using high performance liquid chromatography coupled to quadrupole-Orbitrap mass spectrometry
2016
Abstract A multi-class method for the determination of 24 emerging pharmaceutical residues has been developed and validated. The method is based on solid-phase extraction of wastewater samples using Strata-X cartridges followed by high performance liquid chromatography coupled to hybrid quadrupole − Orbitrap high resolution mass spectrometry (HPLC-Q-Orbitrap-HRMS). A single-laboratory validation procedure showed satisfactory analytical performance. The analysis of 21 samples collected at the wastewater treatment plant in Riga revealed the occurrence of 20 compounds of different therapeutic classes. The highest concentration was found for the central nervous system stimulator caffeine − up t…
Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.
2016
The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strength range 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate …
Sample Preparation to Determine Pharmaceutical and Personal Care Products in an All-Water Matrix: Solid Phase Extraction
2020
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