Evaluation and optimization of chromium removal from tannery effluent by microemulsion in the Morris extractor

In this research a surfactant derived from a vegetable oil (coconut oil) was used to remove chromium from a tannery effluent. In the extraction process, a Morris extractor was used. Important variables used in assessing the optimization of the process included agitation speed, solvent rate and total flow rate. The experiments were conducted using a 2(3) factorial design. According to the response from the experimental design, the effects of each variable were calculated and the interactions between them determined. Response surface methodology was employed to study the effects of the studied variables. The optimum operational conditions were: agitation speed, 428 rpm; solvent rate, 0.37; total flow rate, 2.0 1 h(-1). After extraction process, a re-extraction study was accomplished and the obtained results showed that chromium could be removed from the microemulsion phase by hydrochloric and sulphuric acidic solutions, what allows its reuse in the leather manufacturing process. (C) 2004 Elsevier B.V. All rights reserved.