RESUMEN
La disponibilidad de recurso hídrico de calidad es un factor de gran interés científico, debido a la gran carga de contaminantes de origen antrópico presente en las fuentes de agua, siendo los metales, de especial atención por la bioacumulación y lamtoxicidad. En el presente artículo, se estudia la adsorción de Cromo hexavalente, usando cáscara de cacao, como material adsorbente, así como dos tratamientos químicos a la misma, con hidróxido de sodio y ácido clorhídrico, evaluando su efecto en la remoción del ión metálico. La medición del metal en solución, se hizo mediante espectroscopia UV-Vis, usando el reactivo difenilcarbazida. Se estudió el efecto del tamaño de partícula en el proceso y el ajuste de la cinética, se hizo con los modelos de primer orden, segundo orden, Elovich y difusión. Se encontró que el modelo que mejor se ajustó a los datos experimentales fue el de Elovich, mientras que la isoterma de Freundlich describe mejor el proceso de adsorción; de este modo, se establece que la superficie catalítica del bioadsorbente es heterogénea, exhibiendo diferentes energías de activación. Además, se observó que la modificación con ácido clorhídrico mejoró la capacidad de adsorción del material.
The availability of quality water resources is a factor of great scientific interest because of the high burden of anthropic contaminants in water sources, with particular attention to metals due to their bioaccumulation and toxicity. In this research the adsorption of hexavalent chromium using cocoa shell as adsorbent material, as well as two chemical treatments with sodium hydroxide and hydrochloric acid was studied. The effect of removing this metal-ion was evaluated. Measurement of this metal in aqueous solution was realized by UV-Vis spectroscopy using diphenylcarbazide reagent. The effect of particle size in the process was studied and the adjustment of the kinetics was done with models of first order, second order, Elovich and diffusion It was found that the model with the best fit to the experimental data was Elovich, while Freundlich´s isotherm describes the adsorption process in a better way. Thereby it was established that the catalytic surface of this bioadsorbent is heterogeneous, exhibiting different energies of activation. Furthermore it was observed that the modification with hydrochloric acid improved the adsorption capacity of this material.
RESUMEN
The sorption abilities of leaves powders of Bhringraj , Aerva lanata, Trianthema portulacastrum L for extracting Chromium (VI) from polluted waters have been studied with respect to various physicochemical parameters such as pH, sorption dosage and equilibrium time. The conditions for maximum removal of Chromium (VI) have been optimized. Ten fold excess of common cation ions present in natural waters, viz., Ca2+, Mg2+ , Cu2+, Zn2+, Ni2+ and Fe2+ have synergistic effect in increasing the % removal of Chromate. SO4 2—and Phosphates are found to be interfering with the extractability of Chromates but NO3 - , Chloride, Fluoride and Carbonate have marginal interference. However, the extraction has never come down below 72.0%. Maximum extractions to an extent of 96.0%, 92.0%, and 84.0% from synthetic waters are observed with the leaves powders of Bhringraj , Aerva lanata, Trianthema portulacastrum L respectively at pH:2 and at optimum equilibration time and sorbent concentrations. The methodologies developed are applied to diverse waste water samples collected from industrial effluents and polluted lakes. The procedures are found to be remarkably successful in removing the Chromiume(VI) from waste waters.
RESUMEN
Heavy metals are stable environmental contaminants, causing various alterations in target tissues. Garlic has some beneficial effect in preventing heavy metal induced various alteration. The objective was to investigate the possible protective role of fresh aqueous homogenate of garlic on hematology, erythrocyte antioxidant defense system in male albino rats treated with NiSO4 and K2Cr2O7. Rats were divided into six groups. Group I was untreated control. Group II was given aqueous homogenate of garlic (orally). Group III was administered with nickel sulfate (i.p). Group IV was given NiSO4 and garlic simultaneously. Group V was administered with K2Cr2O7 (i.p). Group VI were treated simultaneously with K2Cr2O7 and garlic. RBC, WBC, platelet count, PCV%, hemoglobin concentration decreased significantly and clotting time increased significantly after nickel treatment. After chromium treatment all the values decreased except clotting time. Increased malondialdehyde and glutathione level after nickel and chromium treatment was observed. Also erythrocyte superoxide dismutase, glutathione peroxidase and catalase activities significantly increased after nickel and chromium treatment. Simultaneous garlic supplementation exhibited protective role to combat nickel toxicity, whereas no such beneficial effects were observed for chromium (VI). Garlic may partially prevent nickel and chromium induced alteration but such ameliorated effects as an antioxidant is only restricted on nickel induced alteration.
RESUMEN
A thorough investigation is made to explore the surface sorption abilities of powders of stems and their ashes of some herbal plants in controlling the Chromium (VI) pollution in waste waters. It is found that the powders of stems and their ashes of Achyranthes aspera, Mentha, Emblica officinalis, Hybiscus roja sinensis, Ocimum sanctum and Psidium guajava have strong affinity towards Chromate at low pH values. % of removal of Chromate is found to be pH sensitive and also depends on sorption concentration and time of equilibration. The conditions for the maximum extraction of Chromate at minimum dosage of sorbent and equilibration time have been optimized. More than 90.0% of removal of Chromate is found. Sorbent concentrations and time needed for the maximum removal of Chromate is less for the ashes of stems than with the raw stem powders. The presence of ten fold excesses of Cations : Ca2+, Mg2+ , Cu2, Zn2+ and Ni2 + and anions like NO3 - ,Chloride, Fluoride and Carbonate have marginally effected the % removal of Chromium (VI) while Sulphate and Phosphate showed some interference with some sorbents but even with them, the % of extractability never comes down to 71.0%. The adoptability of the methodologies developed in this work are tested with respect to diverse waste water samples collected from industrial effluents and in natural lakes and found to be remarkably successful.
RESUMEN
The various dilution levels of treated tannery effluent (T.E.) (10, 25, 50 and 100 %) and Cr 6+ (0.5, 2.0, 5.0 and 10 ppm) were used in experiment to know their effect on seed germination, seedling growth, pigments and enzymes content in Black gram (Phaseolus mungo Roxb.). Chromium is known as the main toxic component of tannery effluent so its various concentration were given to know their effects. For the recovery of plant damage, protective value of 10 and 25 ppm of zinc, potassium and iron sulphate were also given with 50 % treated tannery effluent and 10 ppm Cr 6+ levels in separate petridishes. The different concentrations of tannery effluent and Cr 6+ showed significant reduction in germination percentage, seedling growth (plumule and radicle length, number of lateral roots, fresh and dry weight, and moisture %) and pigments (chlorophyll, pheophytin and carotenoids) with increase in concentrations. The lower doses of tannery effluent (10%) and Cr 6+ (0.5, 2 and 5 ppm) slightly increases the pigments concentration. The amylase activity and total sugar contents were also significantly decreased while catalase and peroxidase activity showed significant increase with rise in concentrations of treatments. The lower concentrations of tannery effluent (dilution 10 and 25%) and Cr 6+ (0.5 and 2 ppm) showed significant increase in total protein contents while decrease at higher concentrations. The zinc, potassium and iron treatments led to recover the damage caused by chromium and tannery effluent in all parameters. In recovery treatments zinc showed highest and significant recovery in maximum parameters. Iron also showed almost similar effect to the zinc while potassium showed minimum recovery.
RESUMEN
In Amazonia, chromium is mainly used in the leather and wood industries. It is responsible for many health problems, because of its toxicity. These industries remove chromium waste by various processes, such as adsorption. This work shows the results of Cr(VI) adsorption by commercial granular activated carbon (GAC) as adsorbent from diluted solutions, and batch systems with controlled pH. The functional groups on the CAG surface was carried out by the Boehm method. In addition, effect of pH on the Cr(VI) adsorption, adsorption equilibrium, and kinetic were studied under experimental conditions (pH = 6, MA = 6g, for 90min.). On the GAC surface, carboxylic groups were found to be in higher concentrations (MAS=0,43 mmol/gCAG), which increase the Cr(VI) adsorption, principally in acidic pH values. The adsorption capacity is dependent on the pH of the solution, due to its influence on the surface properties of the CAG and different ionic forms of the Cr(VI) solutions. The adsorption equilibrium data was adjusted satisfactorily by the Langmuir isotherm (R²=0,988), favorable type. From kinetics adsorption of 20 mg/L and 5 mg/L, the results were compatible with the national legislation (Res. nº 357/05). Therefore, the experimental system using (CAG) was efficient in removing the Cr(VI) from liquid streams containing low concentrations of the metal.
Na Amazônia o cromo é empregado principalmente na indústria de couro e de madeira, sendo responsável por vários problemas de saúde porque é tóxico para os seres vivos. A remoção de cromo de efluentes industriais é feita por meio de diversos processos como a adsorção. Este trabalho mostra os resultados da adsorção de Cr(VI) por carvão ativado granular comercial (CAG) como adsorvente de soluções diluídas empregando um sistema de adsorção batelada com controle de pH. Os grupos funcionais da superfície do CAG foram determinados pelo método de Boehm. Além disso, o efeito do pH na adsorção de Cr(VI), o equilíbrio e a cinética de adsorção foram estudados nas condições experimentais (pH = 6, MA = 6g, tempo de adsorção 90min.). Na superfície do CAG, os grupos carboxílicos foram determinados em maior concentração (MAS=0,43 mmol/gCAG), estes, presentes em concentrações elevadas aumentam a adsorção do metal, principalmente em valores de pH ácidos. A capacidade de adsorção é dependente do pH da solução, devido a sua influência nas propriedades de superfície do CAG e nas diferentes formas iônicas das soluções de Cr(VI). Os dados de equilíbrio da adsorção foram ajustados satisfatoriamente pela isoterma de Langmuir (R²=0,988), tipo favorável. A partir da cinética de adsorção a 5mg/L e 20mg/L, os resultados obtidos foram compatíveis com o valor limite preconizado na legislação nacional (Res. nº 357/05). Portanto, para o sistema experimental utilizando CAG foi eficiente na remoção de Cr(VI) a partir de correntes líquidas contendo baixas concentrações do metal.
RESUMEN
The adsorption of chromium (VI) ions from aqueous solutions has been investigated on crude tamarind fruit shell, HCl treated and Oxalic acid treated shells at room temperatures. The biosorbents are characterized by FT-IR, EDXRF and porosimetry. The biosorption experiments are conducted through batch system. The influence of different experimental parameters such as pH, effect of initial metal ion concentration and effect of dosage of adsorbent on biosorption are evaluated. The adsorption followed first order kinetics. The data are fitted well to Langmuir and Freundlich isotherm models. A comparison is drawn on the extent of biosorption between untreated and treated forms of the tamarind shells. Due to their outstanding adsorption capacities, tamarind shells are excellent sorbents for the removal of chromium ions.
RESUMEN
Cromo(III), Cromo(VI) e Cromo total foram analisados em cento e quatro (104) vinhos comerciais brasileiros, brancos, rosados e tintos. Espectrometria de absorção atômica em forno de grafite foi utilizada nas determinações. Herquat 464 (Aliquat 336), uma mistura de cloreto de metil-tricaprilil amônio (CH3N[(CH2)7CH3]3Cl-) com grupos alquil consistindo principalmente em cadeias C8 - C10, foi utilizado como catalisador de transferência de fase. Valores médios (ug/l) encontrados em vinhos brancos, rosados e tintos foram respectivamente: Cr(III): 11,02 , 12,53 e 8,06; Cr(VI): 8,81 , 26,56 e 5,94; Cr total: 18,14 , 39,08 e 14,00.
Chromium(III), Cr(VI) and Cr total were analyzed in one hundred and four (104) white, pink and red commercial brazilian wines. Atomic Absorption Spectrometric with Graphite Furnace was used for the analysis. Herquat 464 (Aliquat 336), a mixture of methyl trycaprillyl ammonium chioride (CH3N[(CH2)7CH3]3Cl-) with alkyl groups of C8 - C10 chains, was used as a transfer phase catalizer. Mean values (ug/l) found in white, pink and red wines were respectively: Cr(III): 11.02, 12.53 and 8.06; Cr(VI): 8.81, 26.56 and 5.94; Cr total: 18.14, 39.08 and 14.00.