Removal of ferric ions from aluminum solutions by solvent extraction, Part II: kinetics study

Extraction and stripping kinetics of removal of ferric iron from aluminum sulfate solutions using a synergic extractant consisting of di-(2-ethylhexyl) phosphoric acid (P204) and tertiary amine (N235) were reported, in order to explore the basic data for the recovery of aluminum resources from coal spoil. The kinetics of extraction was studied in a highly stirred tank using a focused beam reflectance measurement (FBRM) and a Nikon microscope to monitor the contact between aqueous phase and organic phase. The data were analyzed in terms of a first-order reversible reaction model. The effects of the stirring rate, FBRM data, and temperature on the extraction rate showed that the reaction might be kinetically controlled for extraction and be controlled by a mixed diffusion-chemical reaction mechanism for stripping. The extraction results were compared with those of the system without N235. It was concluded that the presence of N235 decreases the extraction rate of ferric iron. (c) 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901-1907, 2018