| The global climate change is the most critical environmental problem and is also one of the most complicated challenges facing to the whole mankind. CO2emission from fossil fuels combustion contributes to more than60%of the global climate change, which has been the main reason that results in the global climate change. Adsorption-based separation is considered to be one of the most effective technologies to capture CO2from industrial emissions. It is of great importance to develop an efficient CO2sorbent with a high CO2adsorption capacity, a high selectivity, and a long-term regeneration property, In recent years, among various types of CO2capture sorbents, amino-functionalized mesoporous silicas have attracted much attention due to their high surface area, large pore volume, tunable pore size, and high selectivity for CO2adsorption.The purification technology for removing indoor formaldehyde is of great importance because indoor air pollution has become an important social issue with increasing desire to improve the quality of life. Adsorption, scrubbing, and advanced oxidation have been applied to remove volatile organic compounds (VOCs) in air, such as formaldehyde and toluene. Among the above methods, adsorption is a simpler and more effective method to remove gaseous formaldehyde. The point can be summarized as follows:1) Fabrication of amine-functionalized monodispersed porous silica microspheres for efficient CO2adsorption. Amine-functionalized monodispersed porous silica microspheres (MPSM) were prepared by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water-ethanol-dodecylamine mixed solution, then calcined at600℃and finally functionalized with tetraethylenepentamine (TEPA). The CO2adsorption performance of the samples was measured using a Chemisorb2720pulse chemisorption system (Micromeritics, USA). The results showed that calcination temperatures had an obvious influence on the specific surface area, pore volume and pore size of SiO2microspheres. With increasing calcination temperatures, the specific surface area and pore volume increased and pore size decreased. The specific surface area and pore volume of 600℃-calcined SiO2microspheres reached921m2/g and0.48cm3/g, respectively. After surface amine functionalization, the specific surface area and pore volume of the samples drastically decreased and respectively decreased to34m2/g and0.08cm3/g, due to the filling of pore by TEPA molecules. All the TEPA-functionalized samples exhibited good CO2adsorption performance, which were related to the amount of loaded TEPA, adsorption temperature, and the specific surface areas of the samples. A optimal TEPA loading amount (34wt%) and adsorption temperature (75℃) were determined. The maximum CO2adsorption amount (4.27mmol g’1adsorbent) was achieved on the600℃-calcined SiO2microsphere sample with TEPA loading of34wt%. Repeated adsorption/desorption cycle experiments revealed that the TEPA-functionalized SrO2microspheres are good adsorbents for CO2with good cyclic stability.2) Fabrication and CO2adsorption performance of bimodal porous silica hollow spheres with amine-modified surfaces. Amine-functionalized monodispersed porous silica microspheres (MPSM) were prepared by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water-ethanol-dodecylamine mixed solution, then calcined at600℃and finally functionalized with tetraethylenepentamine (TEPA). The CO2adsorption performance of the samples was measured using a Chemisorb2720pulse chemisorption system (Micromeritics, USA). The results showed that calcination temperatures had an obvious influence on the specific surface area, pore volume and pore size of SiO2microspheres. With increasing calcination temperatures, the specific surface area and pore volume increased and pore size decreased. The specific surface area and pore volume of600℃-calcined SiO2microspheres reached921m2/g and0.48cm3/g, respectively. After surface amine functionalization, the specific surface area and pore volume of the samples drastically decreased and respectively decreased to34m2/g and0.08cm3/g, due to the filling of pore by TEPA molecules. All the TEPA-functionalized samples exhibited good CO2adsorption performance, which were related to the amount of loaded TEPA, adsorption temperature, and the specific surface areas of the samples. A optimal TEPA loading amount (34wt%) and adsorption temperature (75℃) were determined. The maximum CO2adsorption amount (4.27mmol g-1adsorbent) was achieved on the600℃-calcined SiO2microsphere sample with TEPA loading of34wt%. Repeated adsorption/desorption cycle experiments revealed that the TEPA-functionalized SiO2microspheres are good adsorbents for CO2with good cyclic stability.3) Silica hollow tubes were synthesized by a hydrothermal method using Cetyltrimethylammonium bromide (CTAB) and biological template poplar catkin (PC) as cotemplates and the PC/SiO2weight ratio R was varied. The prepared samples were further modified with tetraethylenepentamine (TEPA) and characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), and N2physisorption techniques. This was followed by formaldehyde tests at ambient temperature. The results showed that all of the prepared samples contained small mesopores with a peak pore size at ca.2.5nm. The mesopores are found in the hollow tubes. The PC/SiO2weight ratio R exhibited a significant influence on specific surface areas, the P0.3sample has highest specific surface area (896m2/g). All of the TEPA-loaded samples exhibited good formaldehyde adsorption abilities. The results indicated that the formaldehyde adsorption capacity was dependent on the amine group functionalized and the specific surface areas of the samples. The formaldehyde adsorption amount increased proportionally with the specific surface areas. The maximum formaldehyde adsorption amount (20.65mg/g adsorbent) was achieved on the PO.3-50sample. The present study opens new avenues for the utilization of bio-template used for the fabrication of mesoporous hollow tubes. The present study will provides new insight into the design and synthesis of novel porous adsorption materials with high-performance for indoor air cleanup.4) Synthesis of ZrO2hollow spheres and its adsorption kinetics and isotherms to Congo red in water. ZrO2hollow microspheres with hierarchical structures were synthesized via a simple hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, nitrogen adsorption-desorption isotherms. The experiments were carried out in a batch system. In this work, the equilibrium, kinetic and thermodynamic data of the Congo red dye adsorption on ZrO2hollow spheres are studied and compared with ZrO2solid spheres and reagents. ZrO2hollow spheres and ZrO2solid spheres are fabricated by a hydrothermal reaction of zirconium oxychloride in the presence of urea, hydrochloric acid, and ethanol at different temperatures, respectively. Adsorption of Congo red onto the as-prepared samples is investigated and discussed. The adsorption kinetic data are modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations, indicating that pseudo-second-order kinetic equation and intra-particle diffusion model can better describe the adsorption kinetics. Furthermore, adsorption equilibrium data of Congo red on the as-prepared samples are analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data. The adsorption capacities (qmax) of Congo red on ZrO2hollow spheres at30℃determined using the Langmuir equation is59.5mg g-1. The larger adsorption capacities of Congo red for ZrO2hollow spheres versus ZrO2solid spheres and reagents are attributed to its higher specific surface areas. The present work will provide new understanding on the adsorption process and mechanism of Congo red molecules onto ZrO2hollow spheres. |
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