Modified dry bean pod waste (Phaseolus vulgaris) as a biosorbent for fluorescein removal from aqueous media: Batch and fixed bed studies.

This study presents the use of dry bean pods as a solid phase for fluorescein removal from water. The non-pretreated solid phase did not display any sorption properties for the chosen dye. However, interesting sorption properties were observed following a chemical derivative treatment with nitric acid. The study was carried out using both batch and column approaches. Regarding the batch study, all parameters that influence sorption capacity, such, as pH, adsorbent mass, ionic strength, temperature and contact time, were evaluated. A sorptive capacity of 36.80 mg g-1 was obtained in the optimized condition. In the fixed column bed study, the influence of particle size, flow rate and initial concentration of the dye were evaluated through breakthrough curves and a sorptive capacity of 4.35 mg g-1 was obtained. Thermodynamic studies revealed that the adsorption is exothermic and spontaneous. Four different models, Langmuir, Freundlich, Temkin and Redlich-Patterson, were employed. The Akaike information criterion (AIC) was employed to rank the best equilibrium model, which was determined as the Freundlich isotherm. The method was applied to a real sample and the same removal rate was obtained, thus indicating its suitability to wastewater treatment.

A batch and fixed bed column study for fluorescein removal using chitosan modified by epichlorohydrin.

This study evaluates the feasibility of commercial chitosan (CQ) and modified chitosan (MQ) by epichlorohydrin to be used as a solid phase to remove fluorescein (FSC) from aqueous solutions by two different approaches: in batch and on a fixed column bed. For the batch study, all parameters that influence sorption capacity were evaluated, such as: pH, mass, ionic strength, temperature and time of contact. In the optimized condition, 75% removal was obtained for FSC using CQ, while the modification allowed an increase up to 99%, as well as an increase in the stability of the polymer. In the fixed column bed study, the influence of all the parameters was evaluated through breakthrough curves, and the thermodynamics parameters of each approach were obtained. The results of these studies demonstrate that the modification with epichlorohydrin enhanced the sorptive properties (from 35% to 95% in fixed bed experiments) and the polymer stability (making it insoluble), making it suitable to be used in wastewater treatment.

Determination of cocaine in Real banknotes circulating at the State of Rio de Janeiro, Brazil.

This paper shows the result of a study on the extent of cocaine contamination in Real banknotes in circulation in the state of Rio de Janeiro (Brazil). A study of the percentage of contaminated banknotes was made, as well as a study on the contamination of banknotes based on different values, and a study of contamination depending on the region where the banknote was collected. The idea of this last study was to verify if the peculiar characteristics of the region of study (in particular, the city of Rio de Janeiro) influence the amount of cocaine in the banknotes. Some regions have higher consumption/drug trafficking of cocaine than others. Also, some contaminated banknotes confiscated directly from drug dealers and users were analyzed. Also, is showed in this paper all the optimization of the available analytical techniques for making the measurements possible.