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1.
Discov Nano ; 19(1): 78, 2024 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-38696067

RESUMEN

The present research aimed at green synthesis of Ag nanoparticles (AgNPs) based colorimetric sensor using persimmon leaf extract (PLE) for selective detection of mercuric ion (Hg2+). Optimization of reaction conditions viz. pH, concentration of PLE, time was done and further AgNPs were characterized using UV, IR, FE-SEM, EDX, XRD and TEM analysis. The developed AgNPs were evaluated for the selective colorimetric detection of Hg2+ in aqueous medium and fluorescence imaging of Hg2+ ions in liver cell lines. Later, the antibacterial activity of AgNPs was performed against S. aureus and E. coli. The findings of the study revealed that PLE mediated AgNPs exhibited notable limit of detection up to 0.1 ppb, high efficiency, and stability. The antibacterial study indicated that developed AgNPs has impressive bacterial inhibiting properties against the tested bacterial strains. In conclusion, developed biogenic AgNPs has high selectivity and notable sensitivity towards Hg2+ ions and may be used as key tool water remediation.

2.
Environ Monit Assess ; 195(11): 1378, 2023 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-37882833

RESUMEN

In the proposed research, a lanthanum-doped metal-organic framework (La-ATP) has been synthesised to remove phosphate from contaminated aqueous solutions. La-ATP was synthesised by a green energy-saving route using microwave irradiation and exhibited a phenomenal sorption capacity of 290 mg/g for the removal of phosphate. At a minimal dose of 0.1 g/L, 25 mg/L of phosphate gets reduced to 6.3 mg/L within 5 min and reaches equilibrium in 25 min. The isoelectric point of La-ATP was found to be 8.99, and it is efficient in removing phosphate over a wide range of pH 5-10. The existence of commonly occurring competing anions like sulphate, fluoride, chloride, arsenate, bicarbonate, and nitrate does not affect the uptake capacity of La-ATP towards phosphate ions. Furthermore, the robustness of La-ATP is demonstrated by its applicability to remove phosphate from real-life sewage water by reducing 10 mg/L of phosphorus from sewage water to < 0.02 mg/L. The primary mechanism governing phosphate removal was found to be ionic interaction and ligand exchange. Therefore, La-ATP can be considered a viable candidate for the treatment of eutrophic water streams because of its high sorption capacity, super-fast kinetics, and adaptability to contaminated sewage.


Asunto(s)
Estructuras Metalorgánicas , Fosfatos , Aguas del Alcantarillado , Monitoreo del Ambiente , Adenosina Trifosfato
3.
Chemosphere ; 270: 129490, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33418227

RESUMEN

A novel MOF based adsorbent was prepared by functionalization of MIL 88A with mercapto ethanol to yield MIL88A-SH and evaluated for the removal of Hg(II) in water and Hg(0) in air. The prepared MOFs were characterized by field emission scanning electron microscope (FESEM), Transmission electron microscopy (TEM), Brunauer- Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), and zeta X-ray photoelectron microscopy (XPS). The reaction rate was found to be very fast and within 15 min 95.5% Hg(II) was removed. The kinetics data followed pseudo second order model with rate constant values at 1.19 and 2.38 g/µg/min for MIl88A and MIL88A-SH respectively. A very high adsorption capacity in the order 1111.1 mg/g of Hg(II) was found using MIL88A-SH as adsorbent. The uptake was found to be constant in a wide range of pH from 5 to 9. Furthermore, in the presence other interfering metal ions, viz., Cu(II), As(V), Cd(II), Cr(VI), Pb(II), Zn(II), MIL88A-SH demonstrated an excellent adsorption for Hg(II). Around 45.6 mg/g of Hg(0) was found to be adsorbed by MIL88A-SH. XPS, FTIR and XRD studies suggested insitu oxidation Hg(0) to Hg(II) and complexation of Hg(II) with thiol groups during adsorption. Applicability on removal of Hg(II) at ppb levels from drinking water, fast kinetics, wide pH range, a very high sorption capacity, Hg(0) removal, selectivity and recyclability makes MIL88A-SH an efficient adsorbent to tackle mercury contamination.


Asunto(s)
Mercurio , Estructuras Metalorgánicas , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía Infrarroja por Transformada de Fourier
4.
Int J Biol Macromol ; 151: 713-722, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32088223

RESUMEN

Biological macromolecule namely cellulose nanofiber was synthesized from agrowaste sugarcane bagasse. Further, hierarchical nano Fe(0) - FeS was anchored on cellulose nanofibers to obtain CNF-Fe(0)@FeS and it was characterized by various spectral techniques. Formation of FeS2 was confirmed by high resolution TEM and XPS techniques. Anchoring on cellulose nano fibers prevented agglomeration of nanocomposite and furthermore, coating of FeS2 helped in the preservation of Fe(0). Thus the prepared nano composite was very effective in the removal of cationic Methylene blue (MB) dye and anionic Congo red (CR) dye with a maximum adsorption capacity of 200.0 and 111.1 mg/g respectively. Both MB and CR dye followed Pseudo second kinetic with regression coefficients >0.98. Especially for MB dye, it was observed that kinetics of adsorption/degradation was very fast and within 3 min, peak at 370 nm disappeared and 70% reduction in intensity was observed at 660 nm. Further FTIR and XPS revealed evidence for the degradation of adsorbed dye molecules. Considering its high adsorption capacity, degradation potential and ease of preparation using agrowaste makes CNF-Fe(0)@FeS a promising sorbent for the treatment industrial dye effluents.


Asunto(s)
Celulosa/química , Compuestos Férricos/química , Compuestos Ferrosos/química , Nanofibras/química , Adsorción , Colorantes , Cinética , Azul de Metileno , Nanocompuestos , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
5.
Sci Rep ; 9(1): 12639, 2019 09 02.
Artículo en Inglés | MEDLINE | ID: mdl-31477772

RESUMEN

Green environment friendly and novel nano MgS decorated cellulose nanofibres (MgS@CNF) were prepared, characterized and evaluated towards the removal of heavy metal namely, cadmium from aqueous solutions. Cellulose nanofibres acted as a template for effective dispersion of MgS nanoparticles and also aid in the complexation of cadmium ions. In depth X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infra red spectroscopy (FTIR) studies revealed that doped MgS on mild acidification yields insitu production of H2S which effectively complexes cadmium ion to form cadmium sulfide. The reaction followed pseudo first order kinetics with regression coefficient in the order of 0.98. A very high Langmuir adsorption capacity in the order of 333.33 mg/g was obtained for MgS@CNF. Finally, MgS@CNF was applied towards the removal of cadmium from organic and TDS rich tannery waste water. MgS@CNF was effective in bringing down the concentration from ppm to ppb levels.

6.
Chemosphere ; 228: 390-397, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31048236

RESUMEN

Sustainable bio nano composite comprising of nanoMgS/FeS doped cellulose nanofibres (FeMgSCNF) was prepared, characterized by various techniques and assessed for the decontamination of Cr(VI). Cellulose nanofibres (CNF) acts as a template and stabilizer and prevents agglomeration of FeS/MgS nano particles. MgS present in the nano-composite provides a barrier to suppress aerial oxidation of Fe(II) and provided additional source of sulfide ions. An adsorption capacity in the order of 142.8 mg/g of the bionano composite was exhibited towards hexavalent chromium. Both FeSCNF and FeMgSCNF followed pseudo first order and pseudo second order kinetics with regression coefficients >0.96. X-ray photoelectron spectroscopy (XPS) studies indicated that decontamination of Cr(VI) follows the route of electrostatic attraction, ion-exchange followed by reduction of Cr(VI) to Cr(III) and immobilization of Cr(III) as chromic oxide and Fe-Cr mixed oxide. Toxicity characteristics leaching tests revealed the efficacy of immobilization. Finally the developed sorbents were successfully applied to the removal of chromium from tannery waste effluents.


Asunto(s)
Celulosa/química , Cromo/química , Descontaminación/métodos , Sulfato de Magnesio/química , Nanofibras/química
7.
Int J Biol Macromol ; 128: 556-565, 2019 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-30708010

RESUMEN

Cellulose nanofibers were extracted from sugarcane bagasse. Zerovalent­iron (ZVI)/Zirconium(IV) (Zr)/ZVI-Zr doped cellulose nanofibers were prepared, characterized and evaluated for fluoride removal. The prepared nanofibers could effectively remove fluoride within a wide pH range of 3.0 to 8.0. The equilibrium reached within 3 h and the adsorption capacities followed the order ZrZVICNF > ZrCNF > ZVICNF. The Langmuir adsorption capacity of ZrZVICNF was 35.70 mg/g, much higher than various commercial adsorbents. Nitrate, chloride, sulphate, phosphate, has insignificant effect on fluoride adsorption and higher concentrations of bicarbonate and silicate ions affected fluoride sorption. Furthermore insignificant amount of Zr(IV) ions were leached during adsorption owing to its efficient complexation with hydroxyl groups of cellulose and the adsorbent could be successfully regenerated. Spectroscopic analysis revealed that fluoride ion complexed with both Zr(IV) and Fe(II)/Fe(III) ions. Thus high fluoride uptake capacity, faster kinetics, applicability at wide pH range, makes ZrZVICNF as attractive sorbent for defluoridation.


Asunto(s)
Agricultura , Celulosa/química , Fluoruros/aislamiento & purificación , Hierro/química , Nanofibras/química , Residuos , Circonio/química , Adsorción , Fluoruros/química , Concentración de Iones de Hidrógeno , Cinética , Purificación del Agua
8.
Environ Sci Pollut Res Int ; 25(13): 12686-12701, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29468398

RESUMEN

Floating catalytic chemical vapor deposition technique was used for synthesizing carbon nanotubes (CNTs) using ferrocene in benzene as the hydrocarbon source. The functionalization of CNTs was carried out by oxidation followed by grafting of potassium iodide (KI) and mercaptoethanol (HS(CH2)2OH) ligands to produce iodide-grafted CNTs (CNT-I) and thiol-functionalized CNTs (CNT-SH), respectively. The resulting adsorbents have been thoroughly characterized by various techniques. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) studies revealed the efficient grafting of the ligands. Further, their adsorption capacities towards antimonite have been assessed. The adsorption kinetics fitted the pseudo-second-order model for both the adsorbents. Moreover, the adsorption of Sb(III) followed Langmuir and Freundlich's model. The maximum adsorption capacity of CNT-I and CNT-SH for Sb(III) at pH 7 was found to be 200 and 140.85 mg/g, respectively. The interference effect of various ions on the adsorption of antimonite was studied. A suitable mechanism for Sb(III) adsorption has been postulated using TEM, XRD, XPS, and FTIR. The adaptability of the adsorbents was demonstrated by the removal capacity of Sb(III) at parts per billion levels from nuclear decontamination formulation (NAC) and tap water matrix as well.


Asunto(s)
Antimonio/análisis , Nanotubos de Carbono/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Cinética , Oxidación-Reducción , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie
9.
J Hazard Mater ; 274: 132-44, 2014 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-24780855

RESUMEN

Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg(2+) as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S>CNT-I>CNT-OX>CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams.


Asunto(s)
Contaminantes Atmosféricos/química , Mercurio/química , Nanotubos de Carbono/química , Contaminantes Químicos del Agua/química , Adsorción , Contaminación del Aire/prevención & control , Equipos y Suministros Eléctricos , Yoduros/química , Cinética , Iluminación , Oxidación-Reducción , Azufre/química , Propiedades de Superficie , Eliminación de Residuos Líquidos/métodos
10.
Environ Sci Pollut Res Int ; 21(15): 9430-42, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24756676

RESUMEN

Enhanced removal application of both forms of inorganic arsenic from arsenic-contaminated aquifers at near-neutral pH was studied using a novel electrospun chitosan/PVA/zerovalent iron (CPZ) nanofibrous mat. CPZ was carefully examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), atomic fluorescence spectroscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). Application of the adsorbent towards the removal of total inorganic arsenic in batch mode has also been studied. A suitable mechanism for the adsorption has also been discussed. CPZ nanofibers mat was found capable to remove 200.0±10.0 mg g(-1) of As(V) and 142.9±7.2 mg g(-1) of As(III) from aqueous solution of pH 7.0 at ambient condition. Addition of ethylenediaminetetraacetic acid (EDTA) enabled the stability of iron in zerovalent state (ZVI). Enhanced capacity of the fibrous mat could be attributed to the high surface area of the fibers, presence of ZVI, and presence of functional groups such as amino, carboxyl, and hydroxyl groups of the chitosan and EDTA. Both Langmuir and Freundlich adsorption isotherms were applicable to describe the removal process. The possible mechanism of adsorption has been explained in terms of electrostatic attraction between the protonated amino groups of chitosan/arsenate ions and oxidation of arsenite to arsenate by Fentons generated from ZVI and subsequent complexation of the arsenate with the oxidized iron. These CPZ nanofibrous mats has been prepared with environmentally benign naturally occurring biodegradable biopolymer chitosan, which offers unique advantage in the removal of arsenic from contaminated groundwater.


Asunto(s)
Arsénico/química , Biopolímeros/química , Restauración y Remediación Ambiental/métodos , Nanofibras/química , Contaminantes Químicos del Agua/química , Adsorción , Quitosano/química , Restauración y Remediación Ambiental/instrumentación , Agua Subterránea/química , Concentración de Iones de Hidrógeno , Hierro/química , Alcohol Polivinílico/química , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
11.
Environ Sci Pollut Res Int ; 19(6): 2055-62, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22215320

RESUMEN

PURPOSE: Removal of malathion from agricultural runoff was studied using novel copper-coated chitosan nanocomposite (CuCH)-a biopolymeric waste obtained from marine industry. METHODS: Synthesis and characterization of the adsorbent using different spectral techniques like Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer, Emmett, and Teller surface analyzer have been carried out. Equilibrium studies have been carried out to optimize the dose rate, pH, and the reaction time. Parathion and methyl parathion removal were also evaluated by CuCH in the batch mode. Using gas chromatography-mass spectrometry (GC-MS) and FTIR studies suitable mechanism for adsorption has been suggested. RESULTS: The particle size of the adsorbent ranged from 700 to 750 nm. The surface area was found to be 20 m(2) g(-1) with a pore volume of 0.11 cc g(-1). The maximum adsorption capacity of malathion by CuCH was found to be 322.6 ± 3.5 mg g(-1) at an optimum pH of 2.0. Presence of copper ions enhanced the adsorption capacity of the adsorbent. The reaction was found to follow pseudo second-order kinetics with a rate constant of 0.53 g mg(-1) min(-1). Evidence from FTIR indicated that copper ions form a dithionate complex with malathion during the adsorption stage. The adsorbent was found to remove malathion completely from spiked concentration of 2 mg l(-1) in the agricultural run-off samples. It was also found that CuCH removed other organophospurous pesticides like methyl parathion and parathion under prevailing conditions. CONCLUSIONS: The results indicated that CuCH could be applied for the removal of organophosphorous pesticides.


Asunto(s)
Quitosano/química , Restauración y Remediación Ambiental/métodos , Insecticidas , Malatión , Nanocompuestos/química , Contaminantes Químicos del Agua , Adsorción , Quitosano/metabolismo , Cobre/química , Cobre/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Concentración de Iones de Hidrógeno , Insecticidas/análisis , Malatión/análisis , Metil Paratión/análisis , Paratión/análisis , Contaminantes Químicos del Agua/análisis
12.
Environ Monit Assess ; 184(8): 4889-901, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21912870

RESUMEN

The level of arsenic (As) contamination and the geochemical composition of groundwater in Shuklaganj area located on the banks of the Ganges Delta of Kanpur-Unnao district were elucidated. Samples (n = 59) were collected from both India Mark II hand pumps (depth, 30-33 m) and domestic hand pump tube wells (10-12 m) located within 5 km from the banks of Ganges. Samples were analyzed for various parameters, including total inorganic As, sulfate, nitrate, alkalinity, ammonia, and iron. Hydrochemistry of the groundwater aquifer was studied through the trilinear plots between monovalent and divalent cations and anions. In Indian mark II hand pumps, arsenic concentration ranged from below detection limit to 448 µg/L. Most of the samples contained both As(III) and As(V). The pH of the samples ranged from 7.1 to 8.2. Except for a few, most of the samples were reducing in nature as evident by their negative oxidation reduction potentials. A positive correlation for arsenic with iron, ammonia, and dissolved organic carbon shows the probability of biodegradation of organic matter and reductive dissolution of Fe oxyhydroxide processes to leach As in aquifers. For confirmation of the suggested arsenic mobilization mechanism, the presence and absence of sulfate-reducing bacteria and iron-reducing bacteria were also tested.


Asunto(s)
Arsénico/análisis , Monitoreo del Ambiente , Agua Subterránea/química , Contaminantes Químicos del Agua/análisis , India , Cinética , Modelos Químicos , Nitratos/análisis , Sulfatos/análisis , Movimientos del Agua
13.
Chemosphere ; 86(2): 150-5, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22079302

RESUMEN

Evaluation of Chitosan zerovalent Iron Nanoparticle (CIN) towards arsenic removal is presented. Addition of chitosan enhances the stability of Fe(0) nano particle. Prepared adsorbent was characterized by FT-IR, SEM EDX, BET and XRD. It was found that, with an initial dose rate of 0.5 g L(-1), concentrations of As (III) and As (V) were reduced from 2 mg L(-1) to <5 µg L(-1) in less than 180 min and the adsorbent was found to be applicable in wide range of pH. Langmuir monolayer adsorption capacity was found to be 94±1.5 mg g(-1) and 119±2.6 mg g(-1) at pH 7 for As (III) and As (V) respectively. Major anions including sulfate, phosphate and silicate did not cause significant interference in the adsorption behavior of both arsenite and arsenate. The adsorbent was successfully recycled five times and applied to the removal of total inorganic arsenic from real life groundwater samples.


Asunto(s)
Arsénico/química , Quitosano/química , Hierro/química , Nanopartículas del Metal/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Restauración y Remediación Ambiental , Concentración de Iones de Hidrógeno , Cinética
14.
J Hazard Mater ; 185(1): 55-62, 2011 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-20943316

RESUMEN

Removal of hexavalent chromium by xanthated chitosan was investigated in a packed bed up-flow column. The experiments were conducted to study the effect of important design parameters such as bed height and flow rate. At a bed height of 20 cm and flow rate of 5 mL min(-1), the metal-uptake capacity of xanthated chitosan and plain chitosan flakes for hexavalent chromium was found to be 202.5 and 130.12 mg g(-1) respectively. The bed depth service time (BDST) model was used to analyze the experimental data. The computed sorption capacity per unit bed volume (N(0)) was 4.6 ± 0.3 and 78.3 ± 2.9 g L(-1) for plain and xanthated flakes respectively at 10% breakthrough concentration. The rate constant (K(a)) was recorded as 0.0507 and 0.0194 L mg(-1)h(-1) for plain and xanthated chitosan respectively. In flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency of plain and xanthated chitosan decreased with increasing flow rate. The Thomas model was used to fit the column sorption data at different flow rates and model constants were evaluated. The column was successfully applied for the removal of hexavalent chromium from electroplating wastewater. Five hundred bed volumes of electroplating wastewater were treated in column experiments using this adsorbent, reducing the concentrations of hexavalent chromium from 10 mg L(-1) to 0.1 mg L(-1).


Asunto(s)
Cromo/aislamiento & purificación , Contaminantes Químicos del Agua/aislamiento & purificación , Algoritmos , Quitosano/química , Galvanoplastia , Residuos Industriales/análisis , Modelos Químicos , Tamaño de la Partícula , Polisacáridos Bacterianos/química , Eliminación de Residuos Líquidos , Purificación del Agua/métodos
15.
Bioresour Technol ; 101(7): 2173-9, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20005095

RESUMEN

Decontamination of arsenic ions from aqueous media has been investigated using iron chitosan spacer granules (ICS) as an adsorbent. Drying of beads saturated with a spacer sucrose was considered as simple treatment, to prevent the restriction of polymer network and enhance sorption capacity. The novel sorbent was studied in up flow column experiments conducted at different flow rates, pH and bed depth to quantify the treatment performance. It was found that silicate was more inhibitory than phosphate, and the silicate in groundwater controlled the arsenic removal efficiency. The column regeneration studies were carried out for two sorption-desorption cycles using 0.1N NaOH as the eluant. TCLP leaching tests were conducted on the arsenic loaded adsorbent which revealed the containment of arsenic-laden sludge can be managed without adverse environmental impact. The developed procedure was successfully applied for the removal of both As(III) and As(V) from arsenic contaminated drinking water samples.


Asunto(s)
Arseniatos/aislamiento & purificación , Arsenitos/aislamiento & purificación , Quitosano/química , Hierro/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Agua/química , Adsorción , Biodegradación Ambiental , Concentración de Iones de Hidrógeno , Iones , Cinética , Modelos Químicos , Fosfatos/química , Reología , Silicatos/química , Suelo/análisis , Abastecimiento de Agua
16.
Water Res ; 43(15): 3862-70, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19577786

RESUMEN

A study on the removal of arsenic from real life groundwater using iron-chitosan composites is presented. Removal of arsenic(III) and arsenic(V) was studied through adsorption at pH 7.0 under equilibrium and dynamic conditions. The equilibrium data were fitted to Langmuir adsorption models and the various model parameters were evaluated. The monolayer adsorption capacity from the Langmuir model for iron chitosan flakes (ICF) (22.47+/-0.56 mg/g for As(V) and 16.15+/-0.32 mg/g for As(III)) was found to be considerably higher than that obtained for iron chitosan granules (ICB) (2.24+/-0.04 mg/g for As(V); 2.32+/-0.05 mg/g for As(III)). Anions including sulfate, phosphate and silicate at the levels present in groundwater did not cause serious interference in the adsorption behavior of arsenate/arsenite. The column regeneration studies were carried out for two sorption-desorption cycles for both As(III) and As(V) using ICF and ICB as sorbents. One hundred and forty-seven bed volumes of As(III) and 112 bed volumes of As(V) spiked groundwater were treated in column experiments using ICB, reducing arsenic concentration from 500 to <10 microg/l. The eluent used for the regeneration of the spent sorbent was 0.1M NaOH. The adsorbent was also successfully applied for the removal of total inorganic arsenic down to <10 microg/l from real life arsenic contaminated groundwater samples.


Asunto(s)
Arseniatos/análisis , Arsenitos/análisis , Quitosano/química , Hierro/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Agua/química , Adsorción , Arseniatos/química , Arsenitos/química , Restauración y Remediación Ambiental , Fosfatos/química , Silicatos/química , Sulfatos/química
17.
J Hazard Mater ; 169(1-3): 1074-80, 2009 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-19467785

RESUMEN

This paper highlights the mechanistic aspects of white rot fungus Coriolus versicolor as a complexing/reducing agent for chromium bioremediation. The chemical reduction of Cr(VI) to Cr(III) via the formation of Cr(VI) thio ester as an intermediate, is pH dependent and controls the overall chromium adsorption kinetics. The strong adsorption affinity of the biomass towards Cr(VI) anions was evaluated by the Freundlich and the Langmuir adsorption isotherms. The FTIR spectroscopic analysis suggested the involvement of amino, carboxylate, and thiol groups from fungal cell wall in chromium binding and reduction. The mechanism of the adsorption was preferential sequestration along with binding of the metal to the ligating groups present in the biomass followed by reduction to trivalent state. The results indicate step-wise progression of overall reaction dictated and modulated by structural and conformation effects in the biomass that lead to saturation, acceleration, and ultimate saturation kinetics effects.


Asunto(s)
Biodegradación Ambiental , Cromatos/química , Hongos/metabolismo , Adsorción , Biomasa , Pared Celular/metabolismo , Cromatos/aislamiento & purificación , Cromo/metabolismo , Conformación Molecular , Sustancias Reductoras
18.
Chemosphere ; 75(1): 83-91, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19135229

RESUMEN

Threat to human health worldwide due to the natural contamination of arsenic in ground waters has led to extensive studies on factors controlling the distribution of arsenic and conditions leading to arsenic mobilization in different arsenic contaminated areas. Another aspect of the arsenic crisis, especially in South Asia, is the degree of spatial variability of ground water arsenic concentrations. Thus it becomes necessary to study the source and the processes involved in arsenic mobilization into ground water under such conditions. An arsenic contaminated area namely, Ballia district of UP was chosen for this study. A set of 56 samples were collected from India Mark II hand pumps (30-33 m depth) thrice in a year namely pre-monsoon (April '07), monsoon (July '06) and winter seasons (December '06). Nine samples were also collected from deep bore well hand pumps (66-75 m) to study the difference in geochemistry with the shallow pumps. Various water quality parameters like As(III), As(V), sulfate, nitrate, phosphate, bicarbonate, ammonia, were determined. Arsenic concentrations ranged from 0 to 468 microg L(-1) in ground water collected from depths of 30-33 m. In the deeper wells (66-75 m), arsenic concentrations ranged from 12 to 20 microg L(-1). Most samples contained both As(III) and As(V) and the concentration of As(III) was generally equal/higher than As(V). Not much variation of arsenic concentration was observed when sampled in summer, monsoon and winter seasons. Correlation studies among various water quality parameters revealed that reductive dissolution of FeOOH was the most probable mechanism for release of arsenic.


Asunto(s)
Arsénico/análisis , Contaminantes Químicos del Agua/análisis , Abastecimiento de Agua/análisis , Monitoreo del Ambiente , Humanos , India , Estaciones del Año
19.
Sci Total Environ ; 401(1-3): 162-7, 2008 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-18514262

RESUMEN

In this study two relatively new arsenic field kits, namely Wagtech Digital Arsenator (WFTK) and Chem-In Corp field test kit (CFTK) for arsenic were evaluated. The response of the two field test kits to known standards (Both As(III) and As(V)) is detailed. In addition around 157 arsenic-contaminated field samples obtained from various locations of Ballia and Kanpur districts, U.P., India were tested using the two kits and the results were compared with the laboratory-based colorimetric method (silver diethyldithiocarbamate method, SDDC). The concentration of arsenic in the 157 samples ranged from 0 to 468 microg l(-1). WFTK is seen to be suitable for measuring arsenic concentration <5-100 microg l(-1) using the digital meter. CFTK was not able to detect As(V) and its usage is cautioned in Uttar Pradesh where As(V) is seen to occur in appreciable concentrations. The Pearson's correlation between the silver diethyldithiocarbamate method and WFTK was found to be 0.87 and for the corresponding correlation with CFTK was 0.41 in the concentration range used in this study. Spearman's rank correlation coefficients comparing the WFTK and CFTK to laboratory measurements in the concentration range of 0-100 microg l(-1) were 0.95 (p<0.001) and 0.64 (p<0.001) respectively.


Asunto(s)
Arsénico/análisis , Monitoreo del Ambiente/métodos , Juego de Reactivos para Diagnóstico , Contaminación Química del Agua/análisis , Abastecimiento de Agua/análisis , Colorimetría/métodos , Ditiocarba/química , Monitoreo del Ambiente/instrumentación , India , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Abastecimiento de Agua/normas
20.
Bioresour Technol ; 99(18): 9021-4, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18490156

RESUMEN

Decontamination of lead ions from aqueous media has been investigated using cross linked xanthated chitosan (CMC) as an adsorbent. Various physico-chemical parameters such as contact time, amount of adsorbent, concentration of adsorbate were optimized to simulate the best conditions which can be used to decontaminate lead from aqueous media using CMC as an adsorbent. The atomic absorption spectrometric technique was used to determine the distribution of lead. Maximum adsorption was observed at both pH 4 and 5. The adsorption data followed both Freundlich and Langmuir isotherms. Langmuir isotherm gave a saturated capacity of 322.6+/-1.2mg/g at pH 4. From the FTIR spectra analysis, it was concluded that xanthate and amino group participate in the adsorption process. The developed procedure was successfully applied for the removal of lead ions from real battery wastewater samples.


Asunto(s)
Quitosano/metabolismo , Electricidad , Plomo/aislamiento & purificación , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua/aislamiento & purificación , Xantinas/metabolismo , Adsorción , Biodegradación Ambiental , Concentración de Iones de Hidrógeno , Cinética , Temperatura
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