Caffeine Adsorption onto Bentonite Clay in Suspension and Immobilized

Abstract This study describes the use of bentonite in suspension for the caffeine adsorption (pollutant of emerging concern) by taking different conditions of the pH, adsorbent mass, adsorbent calcination temperature and interferents into account. The results were compared with those obtained using bentonite immobilized in alginate beads. The acid medium has a greater efficiency for the caffeine adsorption and the adsorbent calcination temperature exerts, due to structural changes. Caffeine removal higher than 90% was obtained at optimized conditions. The Langmuir model indicated a better fit of the data and the adsorption capacity of caffeine onto bentonite. The bentonite immobilized led to a slower adsorption process in relation to the suspended.

[Isolation of a moderately halophilic bacterium resistant to some toxic metals from Aran and Bidgol Salt Lake and its phylogenetic characterization by 16S rDNA gene]

Heavy metals are toxic for human beings, animals and even plants. For example, nickel causes contact hypersensitivity and also may have carcinogenic effects in human. There are physicochemical and biological methods for removing these elements from environment. Some bacteria are able to remove these elements. In this study, the resistance of bacteria in Aran and Bidgol Salt Lake to heavy metals has been evaluated. Seven bacterial samples of the lake were transferred to Ventosa culture medium. Isolated colonies were grown on the medium containing nickel. The resistant bacteria were transferred to media containing other heavy metal elements. Biochemical, morphological and phylogenetic studies were done based on sequencing of 16S rDNA gene in order to identify the isolated resistant bacterium. In addition, enzymatic potency of the bacteria was evaluated for determination of biotechnological value. 16s rDNA sequencing was applied only for one [out of 46] isolated halophilic bacterium. The bacterium displayed a good potency for growing up in the medium containing 2.5-10% NaCl with a considerable tolerance to nickel and other heavy metals. A bacterium with 98% homology with Salinovibrio costicola species is resistant to some toxic metals and it also has the potency of removing nickel from the contaminated environment and producing some industrial enzymes

Bioremediation of chromium contaminated environments.

Bioremediation is the most promising and cost effective technology widely used nowadays to clean up both soils and wastewaters containing organic or inorganic contaminants. Discharge of chromium containing wastes has led to destruction of many agricultural lands and water bodies. Utilisation of chromium(Cr) reducing microbes and their products has enhanced the efficiency of the process of detoxification of Cr(VI) to Cr(III). This review focuses mainly on the current technologies prevalent for remediation like natural attenuation, anaerobic packed bed bioreactors (using live cells, Cr(VI) reductases or their byproducts) and use of engineered microorganisms. Treatment of wastewaters by biosorption or using biofilms and immobilized microbial cells are also discussed.

Determinación de residuos de halothane en el ambiente de los salones de operaciones / Determination of halothane residues in the environment of the operating rooms

Con el objetivo de demostrar la presencia de contaminantes ambientales en la atmósfera quirúrgica, factor que contribuye a los riesgos profesionales de dicha área, se tomaron muestras de aire de 4 salones y 2 de ellas en la sala de posoperatorio de 1 de los hospitales, siguiendo el método de aspiración con absorbedores de vidrio. La muestra obtenida se analizó por un método espectrofotométrico. Los puntos donde hubo mayor concentración del anestésico estudiado fueron en los más cercanos a la máquina de anestesia y en la sala de posoperatorio en la cabecera del enfermo. Se observó que los niveles más elevados ocurrían cuando no había un buen funcionamiento del aire acondicionado. Las concentraciones encontradas fueron muy superiores a las descritas como aceptables, que son de 0,5 p.p.m.; además, no existía mecanismo de evacuación para los residuos anestésicos