Compressed air-assisted solvent extraction (CASX) for metal removal.
A novel process, compressed air-assisted solvent extraction (CASX), was developed to generate micro-sized solvent-coated air bubbles (MSAB) for metal extraction. Through pressurization of solvent with compressed air followed by releasing air-oversaturated solvent into metal-containing wastewater, MSAB were generated instantaneously. The enormous surface area of MSAB makes extraction process extremely fast and achieves very high aqueous/solvent weight ratio (A/S ratio). CASX process completely removed Cr(VI) from acidic electroplating wastewater under A/S ratio of 115 and extraction time of less than 10s. When synthetic wastewater containing Cd(II) of 50mgl(-1) was treated, A/S ratios of higher than 714 and 1190 could be achieved using solvent with extractant/diluent weight ratio of 1:1 and 5:1, respectively. Also, MSAB have very different physical properties, such as size and density, compared to the emulsified solvent droplets, making separation and recovery of solvent from treated effluent very easy.
Li
Chi-Wang
CW
Department of Water Resources and Environmental Engineering, TamKang University, 151 Ying-Chuan Road, Tamsui 25137, Taipei County, Taiwan. chiwang@mail.tku.edu.tw
Chen
Yi-Ming
YM
Hsiao
Shin-Tien
ST
D000388:Air; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000302:isolation & purification*; D011312:Pressure; D012997:Solvents / Q000302:isolation & purification*
D008670:Metals; D012997:Solvents