Gebrekidan A.,Mekelle University |
Gebrekidan A.,Laboratory of Applied Physical Chemistry and Environmental Technology |
Nicolai H.,Laboratory of Applied Physical Chemistry and Environmental Technology |
Vincken L.,Laboratory of Applied Physical Chemistry and Environmental Technology |
And 11 more authors.
Clean - Soil, Air, Water | Year: 2013
This study aims to examine the efficiency of Opuntia ficus-indica for removing organochlorine pesticides from surface waters. Adsorption properties such as size, dose, and time of O. ficus-indica for aldrin, dieldrin, and dichlorodiphenyltrichloroethane (DDT) were studied through stirring and column methods. Because of their high affinity and swelling characteristics, dried O. ficus-indica was studied in stirring while fresh unpeeled O. ficus-indica was applied in both stirring and column experiments and proved to be well-suited to column application. Before removing pesticides, the column was flashed with distilled water eliminate the turbidity and smell from fresh unpeeled cactus. The removal of pesticides increased with an increasing adsorbent dose and decreased with adsorbent particle sizes. The optimum adsorbent dose is 10g for dried and 15g for fresh unpeeled O. ficus-indica. The experimental results show that O. ficus-indica possesses strong adsorption ability for aldrin, dieldrin, and DDT, and the adsorption isotherm data obeyed the Freundlich model. The results of our small-scale experiments suggest a strong potential to develop local small-scale water treatment units that can be used at the level of individual households or local communities, using a widely available adsorbent. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Vanneste J.,Laboratory of Applied Physical Chemistry and Environmental Technology |
Ormerod D.,Janssen Pharmaceutical |
Theys G.,Janssen Pharmaceutical |
Van Gool D.,Janssen Pharmaceutical |
And 3 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2013
BACKGROUND: In this work the possibility of using membrane cascades to carry out difficult pharmaceutical separations was explored. The effect of configuration on process yield, time and cost was studied for a challenging industrial separation: the separation of an intermediate I (MW 221 g mol-1) from an impurity, ethylene bromide (MW 188 g mol-1). RESULTS: All cascade configurations studied were capable of increasing the purity from a fairly low value, namely 26% to the 90% requirement. The results from the cascade modeling showed that the product yield effectively increased from 35.5% to 84.3% by adding two stages. From a cost analysis of a kilo scale plant it was derived that a two-stage cascade with large area modules yielded the smallest total cost of € 515 082. A 7.0% decrease in cost of product loss or a 7.6% increase in membrane skid cost rendered a single stage economically optimal despite the low product yields. However, if at least six other separations with a comparable process time are carried out each year, then even three stages become economically optimal. CONCLUSION: High resolution separations are technically feasible with membrane cascades. The economic viability of membrane cascades increases dramatically with the cost of the product and the utilization of the equipment. © 2012 Society of Chemical Industry.