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Using diatomite (DE) as the micro-reactor and carrier, the diatomite/AlOOH porous humidity control material (DE/A) was prepared via joint hydrolytic precipitation and hydrothermal treatment. The samples obtained were thoroughly characterized by XRD, ICP-MS, FTIR, nitrogen adsorption, MIP, fractal theory, SEM, EDS, TEM and contact angle for reaction mechanism, surface properties, pore structure, fractal character, and morphology analysis. The humidity control performance and reusability of samples were tested. The thermodynamics analysis was also investigated according to Clausius–Clapeyron equation. The results indicated that DE/A showed a better humidity control performance than DE under different relative humidity and temperature. DE/A also showed good reusability. Humidity control performance of DE was significantly improved with the increasing of mesoporous and hydroxyl content. The structure heterogeneity and surface energy of DE were enhanced. A more reasonable pore size distribution had formed in the DE. Van der Waals force and hydrogen bonds are the main forces for humidity control. [ABSTRACT FROM AUTHOR]

Two amino-functionalized diatomite (DE) composites modified by 3-aminopropyltriethoxysilane (APTS) or glycine (GLY) (i.e., APTS/DE and GLY/DE) were successfully synthesized via the wet chemical method for the time- and cost-efficient removal of indoor formaldehyde (HCHO). First, the optimal preparation conditions of the two composites were determined, and then their microstructures and morphologies were characterized and analyzed. Batch HCHO adsorption experiments with the two types of amino-modified DE composites were also conducted to compare their adsorption properties. Experimental results indicated that the pseudo-second-order kinetic and Langmuir isotherm models could well describe the adsorption process, and the maximum adsorption capacities of APTS/DE and GLY/DE prepared under optimal conditions at 20°C were 5.83 and 1.14 mg·g−1, respectively. The thermodynamic parameters of the composites indicated that the adsorption process was spontaneous and exothermic. The abundant amine groups grafted on the surface of DE were derived from the Schiff base reaction and were essential for the high-efficient adsorption performance toward HCHO. [ABSTRACT FROM AUTHOR]

Zeolite derived from coal-based solid wastes (coal gangue and coal fly ash) can overcome the environmental problems caused by coal-based solid wastes and achieve valuable utilization. In this paper, the physicochemical properties of coal gangue and coal fly ash are introduced. The mechanism and application characteristics of the pretreatment processes for zeolite synthesis from coal-based solid wastes are also introduced. The synthesis processes of coal-based solid waste zeolite and their advantages and disadvantages are summarized. Furthermore, the application characteristics of various coal-based solid waste zeolites and their common application fields are illustrated. Finally, we propose an alkaline fusion-assisted supercritical hydrothermal crystallization as an efficient method for synthesizing coal-based solid waste zeolites. In addition, more attention should be given to the recycling of alkaline waste liquid and the application of coal-based solid waste zeolites in the field of volatile organic compound adsorption removal. [ABSTRACT FROM AUTHOR]

A novel antibacterial thermoplastic polyurethane (TPU) nanofiber membrane was fabricated by electrospinning with the aid of Cu-loaded NaX zeolite (CuX), which showed excellent and long-lasting antibacterial activity against Escherichia coli (E. coli). The crystalline structure, morphology and composition of the obtained NaX zeolite, CuX and CuX/TPU nanofiber membrane were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence (XRF), respectively. The antibacterial activity of CuX/TPU nanofiber membrane against E. coli was investigated by inhibition zone method and plate-counting method, and it is indicated that the inactivation efficiency was increased from 58.40 to 99.85% with increasing the addition of CuX from 5 to 30% in 4 h. The result of kinetics study indicated that the disinfection process accorded with the pseudo-first-order model. The possible antibacterial mechanism was also proposed that the released Cu2+ by CuX in nanofiber membrane destroyed the cell wall and penetrated plasma membrane of E. coli. It is expected that this CuX/TPU nanofiber membrane with excellent antibacterial activity would be a promising candidate for biomedical applications. [ABSTRACT FROM AUTHOR]

Amine-modified diatomite with remarkable formaldehyde (HCHO) removal efficiency was prepared by grafting 3-aminopropyltrimethoxysilane (APTMS) in this research. The interfacial properties and microstructures of the prepared adsorbents were characterized and analyzed. The HCHO adsorption properties of the amine modified diatomite were also systematically studied, and it has been proven to be effective adsorbent with better adsorption performance than activated carbon for the removal of gaseous HCHO. Furthermore, to better explain the experimental results, we performed density functional theory (DFT) study on the adsorption system and calculated the geometry, energy, and charge parameters based on first principles. Also, the underlying adsorption mechanism was proposed detailedly by combining experimentation with DFT calculation, suggesting that amine modified diatomite can be efficient adsorbent for the elimination of gaseous formaldehyde. [ABSTRACT FROM AUTHOR]

Competitive adsorption behavior of Cu(II) and Zn(II) from this binary system by X zeolite was systematically investigated. The kinetic data of Cu(II) and Zn(II) well fitted with pseudo-second order model. In the binary system, Cu(II) exhibits higher affinity and selectivity on X zeolite. Generally, the adsorption capacity of Zn(II) greatly decreased as the initial concentration of Cu(II) increased. On the contrary, the adsorption capacity of Cu(II) increased as the initial concentration of Zn(II) increased. The Langmuir isotherm model can best describe the adsorption isotherms of Cu(II). Furthermore, the competitive adsorption behavior of the X zeolite suggesting that it is endothermic and spontaneous. The physicochemical properties of presently tested X zeolite were characterized before and after adsorption, and the competitive adsorption mechanism was analyzed. It is indicated that the X zeolite synthesized from diatomite could be a promising candidate for separating certain heavy metals from industrial effluent. [ABSTRACT FROM AUTHOR]

The biocidal cations of Cu2+ and Zn2+ were hosted on the surfaces and in the cavities of X zeolite via ion exchange. The microstructure and interface properties of the exchanged zeolite X samples were analyzed by XRD, SEM, XPS, and XRF. The as-prepared samples showed excellent antimicrobial activity towards gram-negative bacteria of Escherichia coli and gram-positive bacteria of Staphylococcus aureus. Furthermore, the batch antimicrobial experiments showed that the bacterial disinfection process fitted well with the first order model. The Cu2+-zeolite showed excellent and better antibacterial performance on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Cu2+-zeolite concentrations of 1000 ppm and 100 ppm, respectively. However, the Zn2+-zeolites were found to be less effective on S. aureus than on E. coli, and the mortalities of E. coli and S. aureus were almost 100% after 1 h with the initial Zn2+-zeolite concentrations of 500 ppm and 1000 ppm, respectively. In addition, the relationships between the apparent rate constant (k) and reagent concentration (C) were also systematically investigated. The present results suggest that the as-prepared samples could be promising antibacterial materials for the efficient disinfection of contaminated water with bacteria. [ABSTRACT FROM AUTHOR]

Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90°, the reaction time is 1 h, and the ratio of the liquid/ solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite. [ABSTRACT FROM AUTHOR]