Chemically Modified Crude Pericarp For Separation Of Molybdenum And Rhenium

In this paper, the crude pericarps persimmon peel and orange peel, which contain persimmon tannin and cellulose respectively, were modified with simple chemical methods, and obtained three types of biosorbents. Then, the application of the sorbents for separation of Mo（VI） and Re（VII） was investigated. The main work and results are described as follows:First of all, persimmon peel was chemically modified by crosslinking with concentrated sulfuric acid to obtain a novel kind of adsorption gel, which was termed as crosslinking persimmon tannin（CPT）. The adsorption behaviors of Mo（VI） and other coexisting metal ions onto the CPT gel were investigated. The gel exhibited high selectivity only for Mo（VI） ions evidenced by the high value of separation factor of molybdenum and rhenium（164.37）, the maximal adsorption capacity was 0.562 mol/kg. To the form of Mo（VI）, the adsorption mechanism of Mo（VI） was studied. A kinetic and thermodynamics study for the adsorption of molybdenum confirmed that the molybdenum adsorption behavior conforms to the Langmuir model and the endothermic adsorption process followed pseudo-second order kinetics. Moreover, its excellent adsorption properties and applicability for Mo（VI） were demonstrated by the removal and separation of Mo（VI） from different Mo-Re containing industrial wastewaters.Sencondly, the orange peel cellulose was saponificated with Ca（OH）₂ and loaded La（III）, Ce（III）, Fe（III）, Zr（IV） to obtain four novel kinds of adsorption gels, which were termed as metal-saponification orange waste（M-SOW）. The adsorption behaviors of Mo（VI） and other coexisting metal ions onto the gels were investigated. The gels exhibited high selectivity only for Mo（VI） ions. This result attributed to the adsorption mechanism of Mo（VI）. The molybdenum adsorption behavior conforms to the Langmuir model with a remarkably high adsorption capacity of Zr（IV）-SOW （1.13 mol/kg） > La（III）-SOW （1.07 mol/kg） > Fe（III）-SOW （0.90 mol/kg） > Ce（III）-SOW （0.88 mol/kg）. A kinetic study for the adsorption of molybdenum confirmed that the endothermic adsorption process followed pseudo-second order kinetics. Furthermore, the adsorbent loaded molybdenum can be eluted with 0.5 mol/L NaOH in two cycles and the rate of elution is over 95 percent.Finally, the orange peel cellulose was respectively modified by ammonia, diethylamine, triethylamine, ethylenediamine to obtain four novel kinds of adsorption gels containing different amidocyanogens, which were termed as N-OW. The adsorption behaviors of Mo（VI） and other coexisting metal ions onto the gels were investigated, and the adsorption mechanism of Mo（VI） was also concluded. The molybdenum adsorption behavior conforms to the Langmuir model with a remarkably high adsorption capacity of en-OW （2.156 mol/kg） > NH2-OW （1.693 mol/kg） > TEA-OW （1.236 mol/kg） > DEA-OW （0.897 mol/kg）. A kinetic study for the adsorption of molybdenum confirmed that the endothermic adsorption process followed pseudo-second order kinetics. Moreover, the dynamic adsorption process was investigated by column experiment. The adsorbent loaded molybdenum can be eluted with 4 mol/L HCl and the rate of elution is 100 percent.