Junsheng Liu

Preparation of zwitterionic hybrid polymer and its application for the removal of heavy metal ions from water

A series of zwitterionic hybrid polymers were prepared from the ring-opening polymerization of pyromellitic acid dianhydride (PMDA) and phenylaminomethyl trimethoxysilane (PAMTMS), and a subsequent sol-gel process. FTIR spectra confirmed the step products. TGA analysis showed that the thermal degradation temperature increased with an increase in PMDA content. As a typical example, sample B was used to separate Cu(2+) and Pb(2+) removal by adsorption. It was indicated that its adsorption for Cu(2+) and Pb(2+) followed Lagergren second-order kinetic model and Langmuir isotherm model, demonstrating that the adsorption process might be Langmuir monolayer adsorption. Meanwhile, it was found that the adsorption capacity of Pb(2+) on sample B is beyond 12 times higher than that of Cu(2+) in 0.1 mol dm(-3) aqueous solution, revealing that it has larger affinity for Pb(2+). The desorption efficiency of Cu(2+) and Pb(2+) in 1 mol dm(-3) HNO(3) solution reached up to 96 and 89%, respectively; indicating that they can be regenerated and recycled in industry. These findings suggest that they are promising adsorbents for the selective removal of Pb(2+) from Pb(2+)/Cu(2+) mixed aqueous solution, and can be applied to separate and recover the heavy metal ions from contaminated water and waste chemicals.

Novel zwitterionic inorganic-organic hybrids: synthesis of hybrid adsorbents and their applications for Cu2+ removal.

A series of zwitterionic hybrid adsorbents were prepared via the ring-opening polymerization of pyromellitic acid dianhydride (PMDA) and N-[3-(trimethoxysilyl)propyl] ethylene diamine (TMSPEDA), and a subsequent zwitterionic process as well as sol-gel reaction. Their applications for Cu(2+) removal by adsorption were performed. FTIR spectra confirmed the step products. TGA revealed that the initial decomposition temperature (IDT) of these zwitterionic hybrid adsorbents could arrive at near 150°C. DSC showed that T(g) values decreased with an increase in PMDA content in the hybrid matrix. Ion-change capacity (IEC) revealed that the cation-exchange capacities (CIECs) and anion-exchange capacities (AIECs) of these hybrid adsorbents were within the range of 9.13-11.49 and 4.97-6.28 mmol g(-1), respectively. Meanwhile, the CIECs and AIECs exhibit an opposite change trend as PMDA content increases. Adsorption experiment indicated that their adsorptions for Cu(2+) ions followed Lagergren second-order kinetic model, surface adsorption and intraparticle diffusion mechanisms might be the major process. These findings demonstrated that they are promising absorbents for the separation and recovery of Cu(2+) ions from contaminated water.

NOVEL NEGATIVELY CHARGED HYBRIDS. 3. REMOVAL OF PB2+ FROM AQUEOUS SOLUTION USING ZWITTERIONIC HYBRID POLYMERS AS ADSORBENT

Using zwitterionic hybrid polymers as adsorbent, the adsorption kinetics and isotherm, thermodynamic parameters of Delta G, Delta H and DeltaS for the removal of Pb(2+) from aqueous solution were investigated. It is indicated that the adsorption of Pb(2+) ions on these zwitterionic hybrid polymers followed the Lagergren second-order kinetic model and Freundlich isotherm model, demonstrating that the adsorption process might be Langmuir monolayer adsorption. The negative values of Delta G and the positive values of Delta H evidence that Pb(2+) adsorption on these zwitterionic hybrid polymers is spontaneous and endothermic process in nature. Moreover, the zwitterionic hybrid polymers produced reveal relatively higher desorption efficiency in 2 mol dm(-3) aqueous HNO(3) solution, indicating that they can be recycled in industrial processes. These findings suggest that these zwitterionic hybrid polymers are the promising adsorbents for Pb(2+) removal and can be potentially applied in the separation and recovery of Pb(2+) ions from the waste chemicals and contaminated water of lead-acid rechargeable battery.

Transport mechanism of microcrystalline silicon thin films

Abstract The dark conductivity, σd(T), and the time-resolved microwave conductivity (TRMC) of hydrogenated microcrystalline silicon (μc-Si:H) films prepared by hot-wire chemical vapor deposition (HWCVD) and very-high-frequency plasma-enhanced CVD have been investigated. The σd(T) simulations were carried out based on a simplified energy band model. Fitting the σd(T) data indicates that the electrical transport mechanism in μc-Si:H film depends on the nanocrystallite volume fraction (Xc). Around room temperature, thermionic emission dominates for samples with low Xc, however, for high Xc, tunneling is the major conduction mechanism. In the low temperature range, the behavior of films with low-Xc is fairly explained by variable range hopping conduction. An activation energy of 0.15 eV related to oxygen was found in HWCVD films. TRMC measurements show that the mobility increases with Xc.

Membrane Potentials Across Hybrid Charged Mosaic Membrane in Organic Solutions

Abstract Membrane potentials across hybrid charged mosaic membrane in organic solutions were measured. Equilibrium swelling degree (SD) and fixed charge density in both organic solutions and water were also determined. Ethylene glycol, ethanol, n -propanol and glycerol were used as organic solutes; meanwhile 0.001mol-dm −3 aqueous KCl solution was utilized as a strong electrolyte to measure the electrical difference. Equilibrium swelling degree indicated that it could be affected by the density of organic solutes; while it enhanced with the increasing density of these solutes. The measurement of fixed charge density showed that the membrane had the maximal absolute value in water among these solvents whether for cationic or anionic groups; the difference of dielectric constant between the water and the organic solutes might be responsible for these change trends. It was confirmed that membrane potentials increased with both the increasing concentration of the organic solutions and the elevated pH values. These results demonstrated that the characteristics of the hybrid charged mosaic membrane could be highly impacted by the properties of the organic solutes. A theoretical model for charged membranes in ternary ion systems of weak electrolyte can be used to explain the above-mentioned phenomena.

Kinetic model investigation on lead(II) adsorption using silica-based hybrid membranes

With the rapid development of lead refineries and the wide application of leaded work in electrical industry, lead(II) pollution has deserved much attention. In this study, the kinetic models of lead(II) adsorption onto silica-based hybrid membranes as solid adsorbents were studied. To study the adsorption mechanism of heavy metal ions on these hybrid adsorbents, the experimental data were linearly fitted using six typical two-parameter kinetic equations (i.e. Lagergren pseudo-first-order and pseudo-second-order, Ritchie second-order and modified second-order, Elovich, as well as intraparticle diffusion models). It was found that the experimental results fitted well with Lagergren pseudo-second-order model, Elovich, and intraparticle diffusion models. These findings are very useful in the design and optimization of silica-based hybrid membranes for lead(II) removal from water by adsorption.

Recent Patents on the Preparation and Application of Hybrid Materials and Membranes

The explosion of both academic and industrial interest in inorganic/organic hybrid materials and membranes over the past decade primarily arised from their practical and potential applications in such fields as chemical separation, electrochemical sensing, and fuel cells. In view of their significance to the academia and industry, this review gave a brief summary on the recent patents reporting the preparation and application of hybrid materials and membranes. The focus was on the novel synthetic methodologies and potential applications of hybrid materials and the corresponding hybrid charged membranes. The current and future developments were also discussed.

Hybrid membrane adsorbents: preparation and their adsorptions for copper(II) ions

AbstractA new type of hybrid membrane adsorbents was prepared via a sol–gel reaction. As typical examples, the adsorption performances of samples D and E for copper(II) ions were investigated. TGA measurement showed that the thermal stability of these hybrid membrane adsorbents could exceed 240°C. DSC thermal analysis displayed that the incorporation of 3-aminopropyl triethoxysilane (APTES) into 3-methacrcypropyl trimethoxysilane (MPTMS) did not result in larger transformation of crystallization in these samples. Adsorption experiments confirmed that the adsorption of copper(II) ions onto the samples D and E followed the Langmuir isotherm model, suggested that such adsorption was Langmuir monolayer adsorption. The negative Gibbs free energy values further demonstrated that copper(II) adsorption onto these hybrid membrane adsorbents was spontaneous in nature. The desorption experiment revealed that these samples could be effectively regenerated via aqueous HCl solution as a desorbent. These findings imply ...