Preparation And Applied Basic Research Of Uranium-Fluorine Adsorbent

The research was supported by the Nuclear Energy Special Project (13zg610301) For solving the fluorine pollution problems during purifying uranium, three adsorbents (Al-Zr-La hydroxide (AZL), carboxymethyl konjac glucomannan loaded lanthanum (CCMKGM-La), thermoplastic konjac glucomannan loaded lanthanum (ATDKGM-La)) were prepared in this work. The sorptive properities for F onto AZL, CCMKGM-La and ATDKGM-La were evaluated in single solution using batch experiments as a function of solution pH, adsorbent dosage, temperature, contact time and initial fluoride ion concentration. And the fixed-bed column adsorption characteristic of fluoride was investigated by ATDKGM-La in detail. The results were shown as follows:1. The adsorption studies for F"1 onto AZL in signle ion system showed that the fluoride uptake was singlely edpended on variation of of pH value of solution and the optimal pH was 3.0.Temperature had a little effect on fluoride sopriotn and removal efficiency of fluoride increased with rising contact temperature. The kinetic data conformed successfully to the pseudo-second-order equation and equilibrium time was 120 min.The isotherm adsorption data for AZL was modeled better by the linear Langmuir equation. The equilibrium sorption capacity of AZL was observed to be 182 mg·g-1. With the SEM-EDX and XPS analysis, it is shown that La is the main active adsorption sites and the adsorption mechanism is ion exchange between F- with OH".2. The adsorption studies for F-1 onto CCMKGM-La in signle ion system showed that the fluoride uptake was singlely edpended on variation of of pH value of solution and the optimal pH was 3.0.Temperature had a little effect on fluoride sopriotn and removal efficiency of fluoride increased with rising contact temperature. The kinetic data conformed successfully to the pseudo-second-order equation and equilibrium time was 200 min.The isotherm adsorption data for CCMKGM-La was modeled better by the linear Langmuir equation. The equilibrium sorption capacity of CCMKGM-La was observed to be 58.1 mg-g"1. With the SEM-EDX and XPS analysis, the adsorption mechanism is ion exchange between F" with OH-.3. The adsorption studies for F-1 onto ATDKGM-La in signle ion system showed that the fluoride uptake was singlely edpended on variation of of pH value of solution and the optimal pH was 3.0.Temperature had a little effect on fluoride sopriotn and removal efficiency of fluoride increased with rising contact temperature. The kinetic data conformed successfully to the pseudo-second-order equation and equilibrium time was 480 min.The isotherm adsorption data for ATDKGM-La was modeled better by the linear Langmuir equation. The equilibrium sorption capacity of ATDKGM-La was observed to be 36.2 mg·g-1. With the SEM-EDX and XPS analysis, the adsorption mechanism is ion exchange between F- with OH-.4. Fluoride sorption performance of the packed column was assessed under variable operating conditions, such as, initial influent ions concentration, bed depths and flow rate. It was found that the breakthrough time and depletion time were shortened with an increase in influent concentration and flow rate, but extended with an increase in bed heights, obviously. The equilibrium uptake (qe.exp) of ATDKGM-La increased with an increase in initial influent concentration and flow rates, but decreased with increase in bed depth. The maximum adsorption capacity was calculated to be 14.61 mg·g-1. The data in regard to the effect of bed depths was fitted well to the Bohrat-Adams model.