Adsorption of chromium and copper in aqueous solutions using tea residue

In this study, adsorption of copper and chromium was investigated by residue of brewed tea [Tea Waste] from aqueous solutions at various values of pH. It was shown that adsorbent dose, copper and chromium ion concentrations in such solutions influence the degree of these heavy metal ions' obviation. The adsorption level of the prepared solutions was measured by visible spectrophotometer. The tea residue adsorbed copper [II] and chromium [VI] ions at initial solution pH by 25% and 3%, respectively. During the experiments the peak adsorption occured in hydrated copper nitrate aqueous solution at pH range of 5-6. Likewise the maximum adsorption appeared in potassium chromate aqueous solution at pH range of 2-3. In addition, tea residue adsorbed about 60 mg/g of copper [II] ion at pH=5, while chromium adsorption was registered at about 19 mg/g at pH=2. The data obtained at the equilibrium state, was compared with Langmuir and Freundlich models. Results showed that regarding the kinetics of adsorption, the uptake of copper [II] and chromium [VI] ions by tea residue was comparatively faster, with the adsorption process exhaustion completed within the first 20 min of the experiments. Furthermore, results revealed that adsorption data concerning the kinetic phase is closely correlated with a pseudo-second order model with R[2] > 0.99 for copper [II] and chromium [VI] ions

Dentin permeability of the apical third in different groups of teeth

This ex vivo study evaluated dentin permeability of the root canal in the apical third of different human groups of teeth. Eighty teeth were used, 8 from each dental group: maxillary and mandibular central incisors, lateral incisors and canines, maxillary first premolars (buccal and palatal roots), mandibular first premolars, and maxillary and mandibular second premolars, totalizing 88 roots that were distributed in 11 groups. The root canals were instrumented, irrigated with 1 percent NaOCl and 15 percent EDTA. Roots were immersed in 10 percent copper sulfate for 30 min and then in 1 percent rubeanic acid alcohol solution for the same period; this chemical reaction reveals dentin permeability by the formation of copper rubeanate, which is a dark-colored compound. Semi-serial 100-µm-thick cross-sections were obtained from the apical third of the roots. Five sections of each apical third were washed, dehydrated, cleared and mounted on glass slides for examination under optical microscopy. The percentage of copper ion infiltration and the amount of tubular dentin were quantified by morphometric analysis. The penetration of copper ions in the apical third ranged from 4.60 to 16.66 percent. The mandibular central and lateral incisors presented the highest dentin permeability (16.66 percent), while the maxillary canines and mandibular second and first premolars presented the lowest dentin permeability (4.60 percent, 4.80 percent and 5.71 percent, respectively; p<0.001). The other teeth presented intermediate permeability. In conclusion, dye penetration into dentin tubules at the apical region is strongly dependent on the group of teeth evaluated.

Este estudo ex vivo avaliou a permeabilidade da dentina do canal radicular do terço apical de diferentes grupos de dentes humanos. Foram utilizados 80 dentes, sendo 8 de cada grupo dental superior e inferior: incisivos centrais, incisivos laterais, caninos, primeiros pré-molares superiores (raízes vestibulares e palatinas), primeiros pré-molares inferiores, segundos pré-molares superiores e inferiores, totalizando 88 raízes, as quais foram distribuídas em 11 grupos. Os canais foram instrumentados, irrigados com NaOCl a 1 por cento e EDTA a 15 por cento. As raízes foram imersas em sulfato de cobre a 10 por cento por 30 min e acido rubeânico a 1 por cento pelo mesmo período. Esta reação química revela a permeabilidade da dentina por meio da formação de um complexo escurecido denominado rubeanato de cobre. Hemi-secções de 100 µm de espessura foram obtidas do terço apical da raiz. Cinco secções do terço apical foram lavadas, desidratadas, diafanizadas e montadas em lâminas para análise em microscopia óptica. A porcentagem de infiltração de íons cobre e a quantidade de dentina tubular foram quantificadas por meio de análise morfométrica. A penetração de íons cobre no terço apical da raiz variou de 4,60 por cento a 16,66 por cento. Os incisivos centrais e laterais apresentaram a maior permeabilidade dentinária (16,66 por cento), e os caninos superiores e segundos e primeiros pré-molares inferiores as menores (4,60 por cento, 4,80 por cento e 5,71 por cento, respectivamente; p<0,001). Os outros dentes apresentaram permeabilidade intermediaria. Conclui-se que a penetração de corante nos túbulos dentinários da região apical é extremamente dependente do grupo de dentes avaliado.

Adsorption of copper, nickel and lead ions from synthetic semiconductor industrial wastewater by palm shell activated carbon

Granular activated carbon produced from palm kernel shell was used as adsorbent to remove copper, nickel and lead ions from a synthesized industrial wastewater.Laboratory experimental investigation was carried out to identify the effect of pH and contact time on adsorption of lead, copper and nickel from the mixed metals solution. Equilibrium adsorption experiments at ambient room temperature were carried out and fitted to Langmuir and Freundlich models. Results showed that pH 5 was the most suitable, while the maximum adsorbent capacity was at a dosage of 1 g/L, recording a sorption capacity of 1.337 mg/g for lead, 1.581 mg/g for copper and 0.130 mg/g for nickel. The percentage metal removal approached equilibrium within 30 min for lead, 75 min for copper and nickel, with lead recording 100%, copper 97% and nickel 55% removal, having a trend of Pb2+ > Cu2+ > Ni 2+. Langmuir model had higher R2 values of 0.977, 0.817 and 0.978 for copper, nickel and lead respectively, which fitted the equilibrium adsorption process more than Freundlich model for the three metals

Fate of copper in intensive shrimp farms: bioaccumulation and deposition in pond sediments / Dinâmica do cobre na carcinicultura intensiva: bioacumulação e deposição em sedimentos de tanques de criação

We present the distribution of Cu in water, sediments and biomass from intensive shrimp (Litopenaeus vannamei Boone, 1931)) farming in northeastern Brazil. The results show no difference in dissolved Cu concentrations between waters entering and leaving the ponds. However, there was a large export of particulate Cu to adjacent environments, showed by extremely high particulate (112 µg.L-1) Cu concentrations in draining waters. Copper concentrations in the bottom sediments of the pond varied with depth from 10 to 20 µg.g-1, being 5 to 7 times higher than the local background. Pond management procedures result in a peculiar vertical distribution of Cu with peak values occurring at sub-surface depths in pond bottom sediments. Bioavailable Cu reaches about 20 percent of the total Cu content in sediments. Notwithstanding the relatively high Cu bioavailability, concentrations in shrimp muscle (23.2 to 63.4 µg.g-1 d.w.) were similar to reported values for reared and natural L. vannamei populations, and much lower than acceptable maximum limits for human consumption. Concentrations in the exoskeleton were always higher than in muscle. Increasing Cu mass, and to a lesser extent Cu concentrations in muscle tissues, occurred simultaneously to a decrease in Cu mass and concentrations in the exoskeleton and vice versa, suggesting a dynamical exchange of Cu between the two compartments. Although Cu fate in intensive shrimp culture does not result in increasing Cu exposure to consumers, the activity is an important source of this metal to adjacent ecosystems, in particular in the pristine environments where most aquaculture activities in NE Brazil takes place.

Este trabalho apresenta a distribuição de Cu em água, sedimentos e biomassa em uma fazenda de cultivo intensivo do camarão Litopenaeus vannamei Boone, 1931, no Nordeste do Brasil. Os resultados mostraram não haver diferenças entre as concentrações de Cu nas águas afluentes e efluentes da fazenda. Entretanto, foi verificada uma grande exportação de Cu para áreas adjacentes associada ao material em suspensão. Nas águas efluentes, a concentração de Cu particulado atingiu até 112 µg.L-1. Em sedimentos, as concentrações de Cu variaram com a profundidade da coluna sedimentar de 10 a 20 µg.g-1, sendo estes valores de 5 a 7 vezes mais altos que as concentrações naturais dos solos e sedimentos locais. O manejo dos tanques de criação resulta em perfis de distribuição de Cu em sedimentos com maiores concentrações em subsuperfície. A biodisponibilidade do Cu nestes sedimentos é elevada e atinge cerca de 20 por cento da concentração total. Apesar da biodisponibilidade elevada, as concentrações de Cu em músculo do L. vannamei (23.2 a 63.4 µg.g-1 peso seco) são similares aos valores reportados para populações naturais da espécie e em diversos de cultivo em outros países, e estão bem abaixo dos limites máximos permitidos para consumo humano. As concentrações de Cu no exoesqueleto foram maiores que no músculo. Um aumento da massa de Cu em músculo ocorreu simultaneamente à diminuição do Cu no exoesqueleto e vice-versa sugerindo uma troca dinâmica do Cu entre os dois compartimentos. Embora a presença do Cu no cultivo intensivo do L. vannamei não represente exposição significativa para os consumidores, a atividade é fonte importante de Cu para os sistemas aquáticos adjacentes.

Accumulation, tolerance and impact of aluminium, copper and zinc on growth and nitrate reductase activity of Ceratophyllum demersum (Hornwort).

Ceratophyllum demersum (homwort) was subjected to toxic concentrations of Al (3 and 9 mg l(-1)), Zn (3 and 9 mg l(-1)) and Cu (2.5 and 7 mg l(-1)) in culture solutions for 15 days. The higher dose of Al enhanced the chlorophyll content significantly (p<0.05) in the first 6 days of treatment while other treatments caused marked reductions. Nitrate reductase activity (NRA) was significantly reduced (p<0.05) byAl, Cu and Zn toxicity and ceased completely in plants treated with Cu by the 6th day of treatment. Dry biomass and relative growth rate were reduced significantly (p<0.05) by metal treatment. Tolerance index of the plant was low for Cu (21.62 and 13.43% at low and high doses, respectively) and moderate for Zn (63.74 and 54.85%) and Al (72.83 and 68.79%). Accumulation ofAl, Zn and Cu was threefold at higher doses compared with the lower doses but the bioconcentration factors (BCF) were very low indicating that this plant is not a hyper accumulator of these metals.

Influence of joint application of heavy metals on level of each metal accumulated in the periwinkle Tympanotonus fuscatus (Gastropoda: Potamididae)

Most laboratory assessments of toxicity and bioaccumulation of heavy metals have been concentrated on the accumulation of these metal ions when exposed singly to the test organisms. However, under the natural environmental settings, the metals are never present in isolation and may interact with each other, therefore justifying the need to study the influence of joint application of metals on accumulated levels in exposed animals. In this study, exposure of the periwinkle Tympanotonus fuscatus to sublethal concentrations (equivalent to 0.1 and 0.01 of 96 h LC50) of heavy metals revealed that they were bioaccumulative varying amounts, depending on the type of metal, exposure period and concentration in the test media. While Zn and Pb ion accumulation increased steadily with exposure time, the amounts of Cu accumulated fluctuated regularly over the 30-day experimental period. The levels of Zn, Cu and Cd bioaccumulated over the 30-day experimental period were reduced by over 2-6 folds (with bioaccumulation ratio values ranging from 0.15 to 0.81) when compared to concentrations of the respective metals accumulated during single bioaccumulation studies. However, Pb concentrations accumulated during the joint action studies increased nearly 2-fold (bioaccumulation ratio range 1.36 to 2.0-fold).

La mayoría de los análisis de laboratorio sobre toxicidad y bioacumulación de metales pesados se han concentrado en la acumulación individual de los iones metálicos en los organismos de prueba expuestos a ellos. Sin embargo, bajo condiciones naturales del ambiente, los metales nunca se presentan en forma aislada y deben interactuar unos con otros, justificando así la necesidad de estudiar el efecto de la aplicación conjunta de metales en animales de prueba. En este estudio la exposición de Tympanotonus fuscatus a concentraciones subletales (0.1-0.01 de 96 h LC50) de metales pesados reveló que la bioacumulación varía según el tipo de metal, el período de exposición y la concentración en el medio de prueba. Mientras los iones de Zn y Pb incrementaron gradualmente su acumulación al pasar el tiempo, las cantidades de Cu fluctuaron regularmente durante los 30 días del experimento. Los niveles de Zn, Cu y Cd bioacumulados durante los 30 días del experimento son de dos a seis veces menores (con un rango de bioacumulación de 0.15-0.81) que los que se obtienen por la exposición a los metales en forma individual. Por el contrario, la acumulación de Pb aumentó al doble (rango de bioacumulación 1.36-2.0).

A geographic information system (GIS) analysis for trace metal assessment of sediments in the Gulf of Paria, Trinidad

The Gulf of Paria is a semi-enclosed shallow basin with increasing coastal development activities along Trinidad's west coast. Sediments present a host for trace metal pollutants from overlying waters, therefore determination of their content is critical in evaluating and detecting sources of marine pollution. This paper presents a Geographic Information System (GIS) analysis of geochemical assessment for trace metals in coastal sediments of the Gulf of Paria. This GIS approach facilitates interpretation of the spatial relationships among key environmental processes. The GIS development involves the integration of spatial and attribute data pertaining to bathymetry, current systems, topography, rivers, land use/land cover and coastal sediments. It employs spatial interpolation and retrieval operations to analyze the total trace metal concentrations of aluminum, copper and lead in the sediments and the clay-enriched sediments, to determine whether they are related to sediment type or are affected by the discharge from anthropogenic sources. Spatial distribution modeling of element concentrations are produced to indicate contamination plumes from possible anthropogenic sources such as rivers entering the Gulf of Paria, and to reveal potential hot spots and dispersion patterns. A direct spatial correlation between clay-enriched sediments and high concentrations of aluminum and lead is detected, however regions of high concentrations of copper and lead indicate a relationship to anthropogenic sources. The effectiveness of GIS for visualization, spatial query and overlay of geochemical analysis is demonstrated.

Cobre, cadmio y plomo en el pez Cyprinodon dearborni, sedimentos y agua en dos lagunas de Venezuela / Cooper, cadmium and lead in the Cyprinodon dearborni fish, in the sediments and in the water in two Venezuela's lagoons

The concentration of copper, cadmium and lead in superficial sediment, water and the fish Cyprinodon dearborni was determined in two coastal lagoons of Sucre State, Venezuela. Chacopata lagoon is hyper saline while Los Patos lagoon is hypo saline and receives significant wastewater from Cumaná city. Water, sediment and fish samples were collected in February 1998. In the laboratory, samples underwent acid digestion and were analyzed by atomic absorption spectophotometry. The mean values of the metals in C. dearborni from the Chacopata lagoon were: 159.26 +/- 210.68 microg/g for Cu, 44.71 +/- 45.58 microg/g for Cd, and 9.31 +/- 23.34 microg/g for Pb, while for Los Patos lagoon the mean values were: 64.88 +/- 16.30, 19.48 +/- 5.81 and 22.85 +/- 20.00, respectively. In the water column, the metal concentration ranges were: 2.3-11.6, 3.9-5.4 and 21-32 mg/l for copper, cadmium and lead, respectively. These results suggest that metal levels in sediment, water column and organisms in both lagoons do not differ, except for lead, even though only Los Patos receives waste water.

Levaduras aisladas de mostos de uva en la zona de Oltrepo Pavese, Italia, y su sensibilidad in vitro frente a compuestos de cobre y zinc / Yeast isolated from musts of grapes in Oltrepó Pavese, Italy, and their in vitro sensibility to zinc and copper compounds

Se investigó durante el periodo 1989-90 en la región de Oltrepó Pavese (Italia), la micota de los mostos provenientes de uvas negras y blancas. De un total de 28 especies levaduriformes aisladas, incluidas en 10 géneros, Saccharomyces, fué el género dominante con las especies S.italicus y S.cerevisiae. Tambien se detectaron frecuentemente levaduras anascosporógenas, tales como Candida valida, Torulopsis (C) holmii y Kloeckera apiculata. Se efectuaron estudios de sensibiliadad in vitro frente a compuestos de CuSO4, ya sea en cepas de S. cerevisiae aisladas de los mostos, como de Alternaria, Botrytis, Cladosporium y Sporobolomyces, aisladas del filoplano de la uva. Las concentraciones de CuSO4 a 0.007M y a 0,062M, fueron fúngicidas para S.cerevisiae y Sporobolomyces roseus respectivamente