Removal and recovery of titanium(Ⅳ) from leach liquor of high-sulfur bauxite using calcium alginate microspheres impregnated with di-(2-ethylhexyl) phosphoric acid

In the leaching solution of high-sulfur bauxite roasted by sulfuric acid,a high concentration of aluminum presented along with titanium and iron.The present work was to remove Ti(IV)from the leach liquor by calcium alginate microsphere sorbent material(CA-P204)based on natural alginate impregnated with di-(2-ethylhexyl)phosphoric acid(D2EHPA)to purify leaching solution.Cation exchange and chelation make major contributions to the adsorption mechanism according to Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.The results showed that Ti(IV)was successfully removed by the CA-P204 adsorbent from the Ti(IV)-Al(III)-Fe(III)ternary system with a dynamic column experiment.The removal rate of titanium was nearly 95%under optimal conditions and the maximum adsorption capacity was 66.79 mg/g at pH 1.0.Reusability of CA-P204 was evaluated over three consecutive adsorption/desorption cycles.The adsorption process was simple,low-cost,and had no waste discharge,suggesting that the CA-P204 was promising,efficient,and economical for removing Ti(IV)from high-sulfur bauxite leaching solution.

Selectivity recovery of molybdenum(VI) from rhenium(VII) by amine-modified persimmon waste

Amine functional group was grafted to obtain modified persimmon waste gel （NH2-CPT） with the focus of development of selective recovery of molybdenum from rhenium. The adsorption behavior of the NH2-CPT gel for various metal ions at varying hydrochloric acid concen-trations was studied. It is found that the NH2-CPT exhibits high affinity for Mo（VI） and no affinity for Re（VII）, Cu（II）, Fe（III）, Mn（VII）, and Zn（II） under the operating conditions. The maximum adsorption capacity for Mo（VI） is 172 mg·g^-1, and the adsorption behavior obeys the Langmuir model. Owing to Mo（VI） as poly-anions, the adsorption mechanism of molybdenum anions could be explained as the anion exchange reactions at weak acid concentration, while neutral molecules could be explained as the complexation reactions at strong acid concentration, respectively. In addition, its excellent adsorption characteristics for Mo（VI） are confirmed by separation of Mo（VI） from Mo to Re containing industrial effluent.