MOF-303(Al)的制备优化及水吸附性能

吸附式空气取水技术可在全球范围内为人们提供清洁的饮用水.本研究采用水热法制备MOF-303(Al)材料,考察水溶剂、金属铝源、反应温度和分散剂等条件对其水吸附性能和结构形貌的影响,并探究水热过程直接实现MOF-303(Al)与无机盐复合的可能性.结果表明,水溶剂和分散剂对MOF-303(Al)的水吸附性能影响较小,其水吸附容量均为0.4 g·g^(-1),且能在0.5 h内达到饱和吸附;温度和铝源显著影响材料的水吸附性能,水吸附容量变化幅度为0.3 g·g^(-1);减少水热过程的洗涤步骤能直接完成无机盐与MOF-303(Al)的复合,且材料在95%RH时的吸附容量达2.055 g·g^(-1).

MOFs用于太阳能吸附式空气取水研究进展

总结了太阳能吸附式空气取水原理、MOFs水吸附机理、单体MOF的制备方法、MOFs及其衍生的复合材料水吸附性能,并与本团队对太阳能吸附式空气取水研究相结合,综合分析表明,国内外学者越来越关注并投入MOFs制备方法、开发具有高吸附性能的单体MOFs及其复合材料等方面的研究,相关的研究成果有望将其推广到实际应用中。将MOFs应用于干旱沙漠地区为人们提供饮用水具有潜在的应用前景。

Ammonia nitrogen removal from aqueous solution using zeolite modified by microwave-sodium acetate

The characteristics of the zeolite modified by microwave and sodium acetate and its sorption of ammonia-nitrogen from simulated water sample were investigated.The results show that the modified zeolite by microwave-sodium acetate(SMMZ)has a high sorption efficiency and removal performance.The ammonia-nitrogen removal rate of SMMZ reaches 92.90%.The surface of SMMZ becomes loose and some pores appear,the specific surface area,total pore volume and average pore diameter increase after modification.Compared to the natural zeolite,SMMZ has a more concentrated pore size distribution in the range of 0-10 nm.The cation exchange capacity(CEC)of SMMZ is higher than that of the natural zeolite.And the ammonia nitrogen removal rate is consistent with the change of CEC.The SMMZ possesses rapid sorption and slow balance characteristics and ammonia-nitrogen sorption is consistent with both Langmuir adsorption isotherm model and Freundlich adsorption isotherm model.The adsorption kinetics of ammonia-nitrogen follows the pseudo-second order kinetic model.

Porous g-C3N4 with enhanced adsorption and visible-light photocatalytic performance for removing aqueous dyes and tetracycline hydrochloride

Porous g-C3N4samples were obtained by simply calcining bulk g-C3N4in static air in a muffle oven.The photocatalytic performance of these samples was evaluated through the removal of aqueous organic dyes（methylene blue and methyl orange）and tetracycline hydrochloride under visible-light irradiation（λ〉420 nm）.Compared to bulk g-C3N4,porous g-C3N4exhibited much better capability for removing these contaminants,especially under visible-light irradiation,due to the enlarged specific surface area and more efficient separation of photogenerated charge carries.In particular,porous g-C3N4obtained by calcining bulk g-C3N4in air at 525℃ showed the highest visible-light-driven catalytic activity among these samples.Superoxide radical anions（·O2^-）were found to be the primary active species responsible for photodegradation.

Adsorption of Heavy Metal Ions by Adsorbent from Waste Mycelium Chitin

The adsorption properties of chitin adsorbent from mycelium of fermentation industries for the removal of heavy metal ions were studied. The result shows that the chitin adsorbent has high adsorption capacity for many heavy metal ions and Ni2+ in citric acid. The influence of pH was significant:When pH is higher than 4.0, the high adsorption capacity is obtained,otherwise H+ ion inhibits the adsorption of heavy metal ions. The comparison of the chitin adsorbent with some other commercial adsorbents was made, in which that the adsorption behaviorchitin adsorbent is close to that of commercial cation exchange adsorbents, and its cost is much lower than those commercial adsorbents.

Adsorption properties of CFBC ash-cement pastes as compared with PCC fly ash-cement pastes

Circulating fluidized bed combustion （CFBC） ash can be potentially used as supplementary cementitious materials for concrete production due to its desirable pozzolanic activity. The adsorption properties of CFBC ash-cement pastes were studied, and ordinary pulverized coal combustion （PCC） fly ash-cement pastes were used as control. The water-adsorption and superplasticizer （SP）-adsorption properties of the pastes were evaluated by water demand and UV-visible absorption spectroscopy respectively. The results show that CFBC ash-cement system has greater compressive strength as compared with PCC fly ash-cement system at a given curing age, although the water demand of the former is significantly higher than that of the latter. CFBC ash-cement pastes possess higher adsorption ability of aliphatic SP than PCC fly ash-cement pastes and the adsorption amount increases with an increase in ash replacement ratio. CFBC ash- cement pastes exhibit lower workability with higher slump loss. It is concluded that CFBC ash can be potentially used as supplementary cementitious material in concrete production, but the mix design of CFBC ash concrete needs to be appropriately adjusted. It is suggested that CFBC ash is used for the production of the concrete needing low flowability.

Fabrication and adsorption property of novel adsorbent for potential application to wastewater with Fe(Ⅲ) ions

The spherical macroporous cellulose(SMC) was fabricated using medical absorbent cotton as raw material and nano CaCO3 as porogenic agents.And then,the phenylglycine was grafted onto the SMC to obtain the novel spherical macroporous cellulose derivative adsorbent(PSMC).FT-IR and scanning electron microscope(SEM) were employed to characterize the adsorbents and Fe3+ ions served as model solute to evaluate the adsorption property of the adsorbents.The experimental results show that the amount of porogenic agents and the value of pH have obvious influence on adsorption capacity of the adsorbents.The data of adsorption kinetic and isotherm display that the adsorbents possess excellent equilibrium adsorption capacity(348.94 mg/g) and have a bright prospect and considerable potential in the treatment of Fe3+ ions in wastewater.

Preparation of MnO_2 and calcium silicate hydrate from electrolytic manganese residue and evaluation of adsorption properties

Electrolytic manganese residue(EMR), a high volume byproduct resulting from the electrolytic manganese industry, was used as a cheap and abundant chemical source for preparing MnO2 and EMR-made calcium silicate hydrate(EMR-CSH). The MnO2 is successfully synthesized from the metal cations extracted from EMR, which can effectively recycle the manganese in the EMR. By the combination of XRD, SEM and EDX analysis, the as-prepared MnO2 is found to exhibit a single-phase with the purity of 90.3%. Furthermore, EMR-CSH is synthesized from EMR via hydrothermal method. Based on the detailed analyses using XRD, FT-IR, FE-SEM, EDX and BET surface area measurement, the product synthesized under the optimum conditions(p H 12.0 and 100 °C) is identified to be a calcium silicate hydrate with a specific surface area of 205 m2/g incorporating the slag-derived metals(Al and Mg) in its structure. The as-synthesized material shows good adsorption properties for removal of Mn2+ and phosphate ions diluted in water, making it a promising candidate for efficient bulk wastewater treatment. This conversion process, which enables us to fabricate two different kinds of valuable materials from EMR at low cost and through convenient preparation steps, is surely beneficial from the viewpoint of the chemical and economical use of EMR.

Synthesis and adsorption property of zeolite FAU/LTA from lithium slag with utilization of mother liquid

Co-crystalline zeolite FAU/LTA-0 was synthesized by hydrothermal method from lithium slag. To make the most of excess silicon and alkali sources in mother liquid derived from FAU/LTA-0, zeolite FAU/LTA-I b was synthesized in the same method with the use of mother liquid by adding a certain amount of aluminum source. Influences of different adding ways of aluminum source and recycling dosages of mother liquid on synthesis of zeolites FALl/ LTA with mother liquid were investigated. The phase, microstructure and thermostability of FAU/LTA-0 and FAU/LTA-lb were characterized by XRD, SEM and TG-DTA. The calcium and magnesium cation exchange capacities （CECs） of the zeolites were determined. The results have shown that co-crystalline zeolite can be synthesized with the use of mother liquid by adding aluminum source after 2 h of reaction. Compared with FAU/LTA-0, the crystal twinning structure of FAU/LTA-lb became weaker, the grain size was smaller, and the thermostability was better. With a lower dosage of mother liquid, the content of P-type impurity in product decreased significantly, and the content of LTA phase increased. The reuse rate of mother liquid can reach 48%. The CECs of FAU/LTA-I b-150 can reach 343 mg CaCO3. g-1 and 180 mg MgC03. g-1, showing more excellent adsorption capacities than FAU/LTA-0 and commercial zeolite 4A. The full recycling use of mother liquid to synthesize zeolite FAU/LTA which can be applied for detergent not only improves resource utilization but also reduces oroduction cost.

Adsorption Refrigeration Performance of Shaped MIL-101-Water Working Pair

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa （MIL-101-3）. The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.

Influence of Water Vapor on Silica Membrane： Adsorption Properties and Percolation Effect

The influence of water vapor on silica membrane with pore size of ,-4A has been investigated in terms of adsorption properties and percolation effect at 50 and 90 ℃. Two methods are employed： spectroscopic ellipsometry for water vapor adsorption and gas permeation of binary mixture of helium and H2O The adsorption behaviors on the silica membrane comply with the first-order Langmuir isotherm. The investigation demonstrates that helium flux through the silica membrane decreases dramatically in presence of H20 molecules. The transport of gas molecules through such small pores is believed not to be continuous any more, whereas it is reasonably assumed that the gas molecules hop from one occupied site to another unoccupied one under the potential gradient. When the coverage of H20 molecules on the silica surface increases, the dramatic decrease of helium flux could be related to percolation effect, where the adsorbed H20 molecules on the silica surface block the hopping of helium molecules.

Recovery Properties of Polysulfone Hollow Fiber Chelating Membrane Modified with Thiourea for Mercury (Ⅱ)

The adsorption isotherms of the polysulfone hollow fiber chelating membrane modified with thionrea as chelating groups for Hg^2＋ were determined. The effects of mobile phase conditions and the operating parameters on removal performance of the chelating membrane for Hg^2＋ were also investigated. The recovery of Hg^2＋ decreased at low pH and the optimum range of pH was from 6 to 7. The feed concentration effected on recovery of Hg^2＋ at the specified loading amount of Hg^2＋. The Hg^2＋ could be removed from different concentration feed solution by chelating membrane. The increase of feed flow rate led to slight decrease of recovery of Hg^2＋ at the specified loading amount of Hg^2＋. The chelating membrane could be operated at height feed flow rate and a large-scale removal of H^2＋ could be realized. With the increase of load amount, Hg^2＋ recovery decreased, but the saturation degree of chelating membrane increased. According to required recovery of H^2＋ and the saturation degree of chelating membrane, the optimum loading amount of Hg^2＋ should be selected in the actual removal of H^2＋.