Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li^+ from brines and sea water.Here,we report a lithium ion-sieve which was successfully loaded onto tubular α-A...Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li^+ from brines and sea water.Here,we report a lithium ion-sieve which was successfully loaded onto tubular α-Al2 O3 ceramic substrates by dipping crystallization and post-calcination method.The lithium manganese oxide Li4 Mn5 O(12)was first synthesized onto tubular α-Al2 O3 ceramic substrates as the ion-sieve precursor(i.e.L-AA),and the corresponding lithium ion-sieve(i.e.H-AA) was obtained after acid pickling.The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM).Both L-AA and H-AA showed characteristic peaks of α-Al2 O3 and cubic phase Li4 Mn5 O(12) and the peaks representing cubic phase could still exist after pickling.The lithium manganese oxide Li4 Mn5 O(12) could be uniformly loaded not only on the surface of α-Al2 O3 ubstrates but also inside the pores.Moreover,we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g^-1.After 12 h adsorption,the adsorption balance was reached.After 5 cycles of adsorption,the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity.The process of H-AA adsorption for Li^+correlated with pseudo-second order kinetic model and Langmuir model.Adsorption thermodynamic parameters regarding enthalpy(△N), Gibbs free energy(△G) and entropy(AS) were calculated.For the dynamic adsorptiondesorption process of H-AA,the H-AA exhibited excellent adsorption performance to Li^+ with the Li^+ dynamic adsorption capacity of 9.74 mg·g^-1 and the Mn^2+dissolution loss rate of 0.99%.After 3 dynamic adsorption-desorption cycles,80% of the initial dynamic adsorption capacity was still kept.展开更多
Adsorption operation is of great importance for separation and purification of semi-synthetic cephalosporin compounds in pharmaceutical industry. The adsorption dynamics of Cefoselis hydrochloride(CFH) on XR 920 C ads...Adsorption operation is of great importance for separation and purification of semi-synthetic cephalosporin compounds in pharmaceutical industry. The adsorption dynamics of Cefoselis hydrochloride(CFH) on XR 920 C adsorbent in fixed bed was predicted by the model of modified film-pore diffusion(MFPD). The intraparticle diffusion equation and mass balance equation in fixed bed are discretized into two ordinary differential equations(ODEs) using the method of orthogonal collocation which largely improves the calculation accuracy. The MFPD model parameters including the pore diffusion coefficient(Dp), external mass-transfer coefficient(kf), and the axial dispersion(DL) were estimated. The kfvalue was calculated by the Carberry equation, in which the effective diffusion coefficient Dewas fitted based on Crank Model through experimental data. Moreover, three key operating parameters(i.e., initial adsorbate concentration; flow rate of import feed, and bed height of adsorbent) and the corresponded breakthrough curves were systematically studied and optimized. Therefore,this research not only provides valuable experimental data, but also a successfully mathematical model for designing the continuous chromatographic adsorption process of CFH.展开更多
基金This work was financially supported by National Key Research and Development Program(2018YFE0203502),ChinaPrimary Research and Development Plan ofJiangsu Province(BE2019117),China and National Students'Platform for Innovation and Entrepreneurship Training(201910291051Z),China.
文摘Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li^+ from brines and sea water.Here,we report a lithium ion-sieve which was successfully loaded onto tubular α-Al2 O3 ceramic substrates by dipping crystallization and post-calcination method.The lithium manganese oxide Li4 Mn5 O(12)was first synthesized onto tubular α-Al2 O3 ceramic substrates as the ion-sieve precursor(i.e.L-AA),and the corresponding lithium ion-sieve(i.e.H-AA) was obtained after acid pickling.The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM).Both L-AA and H-AA showed characteristic peaks of α-Al2 O3 and cubic phase Li4 Mn5 O(12) and the peaks representing cubic phase could still exist after pickling.The lithium manganese oxide Li4 Mn5 O(12) could be uniformly loaded not only on the surface of α-Al2 O3 ubstrates but also inside the pores.Moreover,we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g^-1.After 12 h adsorption,the adsorption balance was reached.After 5 cycles of adsorption,the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity.The process of H-AA adsorption for Li^+correlated with pseudo-second order kinetic model and Langmuir model.Adsorption thermodynamic parameters regarding enthalpy(△N), Gibbs free energy(△G) and entropy(AS) were calculated.For the dynamic adsorptiondesorption process of H-AA,the H-AA exhibited excellent adsorption performance to Li^+ with the Li^+ dynamic adsorption capacity of 9.74 mg·g^-1 and the Mn^2+dissolution loss rate of 0.99%.After 3 dynamic adsorption-desorption cycles,80% of the initial dynamic adsorption capacity was still kept.
基金Supported by the National Natural Science Foundation of China(U1407122)the Innovation Project of Jiangsu Province(CXZZ13_0451)
文摘Adsorption operation is of great importance for separation and purification of semi-synthetic cephalosporin compounds in pharmaceutical industry. The adsorption dynamics of Cefoselis hydrochloride(CFH) on XR 920 C adsorbent in fixed bed was predicted by the model of modified film-pore diffusion(MFPD). The intraparticle diffusion equation and mass balance equation in fixed bed are discretized into two ordinary differential equations(ODEs) using the method of orthogonal collocation which largely improves the calculation accuracy. The MFPD model parameters including the pore diffusion coefficient(Dp), external mass-transfer coefficient(kf), and the axial dispersion(DL) were estimated. The kfvalue was calculated by the Carberry equation, in which the effective diffusion coefficient Dewas fitted based on Crank Model through experimental data. Moreover, three key operating parameters(i.e., initial adsorbate concentration; flow rate of import feed, and bed height of adsorbent) and the corresponded breakthrough curves were systematically studied and optimized. Therefore,this research not only provides valuable experimental data, but also a successfully mathematical model for designing the continuous chromatographic adsorption process of CFH.
