Biosorption of lead(II) and chromium(VI) on groundnut hull: equilibrium, kinetics and thermodynamics study / Biosorción de plomo (II) y cromo (VI) en cáscaras de maní: estudio de equilibrio, cinética y termodinámica

The biosorption of lead(II) and chromium(VI) on groundnut hull was investigated. Batch biosorption experiments were conducted to find the equilibrium time and biosorption capacity. Effect of parameters like pH, temperature and initial metal concentration was studied. The maximum biosorption capacity of lead(II) and chromium(VI) was found to be 31.54 +/- 0.63 and 30.21 +/- 0.74 mg g-1, respectively. The optimum pH for lead(II) and chromium(VI) removal was 5 ± 0.1 and 2 +/- 0.1, respectively. The temperature change, in the range of 20 - 45ºC affected the biosorption capacity. The maximum removal of lead(II) was achieved at 20 +/- 2ºC, where as maximum uptake of chromium(VI) was observed at 40 +/- 2ºC. The biosorption data was fitted to the Langmuir and the Freundlich isotherm models. The Langmuir model showed better representation of data, with correlation coefficient greater than 0.98. The kinetics of biosorption followed the pseudo second order kinetics model. The thermodynamics parameters were evaluated from the experimental data.

Estudios de bioadsorción de plomo por saccharomyces cereviceae en soluciones acuosas / Studies of lead biosorption by saccharomyces cereviceae in aqueous solutions

El ecosistema del lago Titicaca (Puno, Perú) y sus tributarios, viene siendo perturbado por metales pesados producto de la actividad minera emergente. Para controlar y reducir la contaminación existen procesos biológicos llevados a cabo por microorganismos como las levaduras (biorremediación). Este trabajo de investigación tiene como objetivos evaluar la capacidad de bioadsorción de plomo mediante Saccharomyces cereviceae en soluciones acuosas y la influencia de dos niveles de pH durante la bioadsorción. Para esto se ensayaron dos concentraciones de S. cereviceae (cel/mL), las cuales fueron cuantificadas por un hemocitómetro y luego traspasadas a una solución con concentraciones conocidas de plomo (5 y 25 mg/L). Se realizaron lecturas de las concentraciones de plomo a los 5, 60 y 120 minutos. La mayor capacidad de bioadsorción resultó cuando S. cereviceae estaba a una concentración de 5 x 106 cel/mL, y el pH óptimo fue de 5,14. Se concluye que S. cereviceae constituye una buena alternativa para la bioadsorción de plomo, quedando abierta su validación en condiciones de campo en el altiplano peruano.

Lake Titicaca's ecosystem and that of its tributaries in Puno (Peru) are being disturbed by heavy metals resulting from emergent mineral activity. Biological processes involving microorganisms such as yeasts (bioremediation) are being used for controlling and reducing such pollution. This research was aimed at evaluating Saccharomyces cereviceae's lead biosorption capacity in aqueous solutions and evaluating the influence of two pH levels on biosorption. Two S. cereviceae concentrations (cel/mL) were tested; these concentrations were quantified in a haemocytometer and then put into a solution having a known lead concentration (5 and 25 mg/L). Lead concentrations were read after 5, 60 and 120 minutes. The results revealed that the best biosorption level was obtained with a 5 x 106 cel/mL S. cereviceae concentration at 5.14 pH. S. cereviceae thus constitute a good alternative for lead biosorption; however, its validation in Peruvian altiplano field conditions remains to be tested.

Effect of dried garlic powder [allium sativum] on lead content of different tissues following subclinical lead poisoning in goats

Efficacy of garlic [Allium sativum] to reduce tissue lead concentration was evaluated experimentally in goats. Eight crossbred female goats, randomly divided into two groups [A and B] were used. Goats of groups A and B received lead acetate orally at the dose of 80 mg/kg body weight, daily for 5 days. At the end of the period, goats of group B received dried garlic powder at the dose of 45 g/day/animal, orally for 5 days. Goats of group A served as lead exposed untreated controls. Comparison between mean lead concentrations of serum, urine and different tissues [bone, lung, heart, liver, kidney and skeletal muscle] of group A and B at the end of experiment showed respectively 69.6, 32.35,46.7, 34.2,27, 24.8, 9.6 and 46.6 percent reduction in group B [P<0.05]. Use of garlic dry powder following subclinical lead poisoning in goats was found to reduce tissue lead concentration considerably indicating the potential therapeutic activity of garlic against lead toxicity in goats

Opiatergic participation in the thirst-inhibiting effect of acute third ventricle injections of cadmium (Cd 2+ ) and lead (Pb 2+ )

We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 ñ 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 ñ 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 ñ 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 ñ 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 ñ 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 ñ 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain

Riesgo plúmbico en imprentas de Lima Metropolitana y Callao / Plumbic risk in printing of Lima and Callao

Se relaciona los resultados obtenidos en trabajadores gráficos con intoxicación plúmbica aparentemente asintomática de diferentes imprentas tipográficas de Lima Metropolitana y sectores del Callao. Se agrupó 128 trabajadores según sexo, edad, tiempo de servicio, horas de trabajo, grado de intoxicación, de incidencia y oficio. Se determinó la concentración de plomo en sangre por el método de espectrofotometria de absorción atómica como un reflejo de la exposición laboral, obteniéndose en ayudantes de linotipistas:60.81 ug Pb por ciento y en cajistas 29.55 ug Pb por ciento, en linotipistas 48,44 ug Pb por ciento e imprsores 39.91 ug Pb por cientos estas últimas de incidencia media. El grado de absorción industrial de plomo en sangre esta relacionada con la ocupación que realiza. De las imprentas visitadas el 59 por ciento torna medidas de prevención, mientras que el 41 por ciento no se demuestra la existencia de trabajadores gráficos con una mayor concentración de plumbenig con respecto a los límites máximos permisibles en industrias. Se concluye que la carencia de medidas de protección, prevención y hábitos ocupacionales inadecuados, son factores que condicionan con mayor riesgo plumbico.