酸活化膨胀蛭石的制备及吸附性能研究

基于工业蛭石具有良好的加热膨胀性、阳离子交换性和吸附性,对采自新疆尉犁蛭石矿的工业蛭石样品进行微波化学膨胀处理和酸活化处理,并对处理后的样品进行了XRD、比表面积和脱色率等分析.考察了酸浓度、时间、温度等实验参数对酸活化样品脱色性能的影响,确定了最佳工艺条件.结果表明:膨胀蛭石样品在酸浓度为2.5mol/L,活化时间为...     

Uptake of Ni(II) Ions from Aqueous Solution by Kaolinite and Montmorillonite: Influence of Acid Activation of the Clays

Abstract

Kaolinite and montmorillonite were treated with 0.25 M H₂SO₄ and the acid activated clays along with the parent clays were tested for their uptake capacity for Ni(II) ions from aqueous solution. The batch adsorption experiments were conducted under a set of variables (concentration of Ni(II) ion, amount of clay, pH, time and temperature of interaction). Increasing pH favored Ni(II) uptake till the ions were precipitated as the insoluble hydroxides at pH > 8.0. The uptake was rapid up to 40 min and equilibrium was obtained within 180 min. The kinetics of the process was evaluated by subjecting the results to a number of models like the pseudo-first order, second order, Elovich equation, liquid film diffusion, and intra-particle diffusion and it was found that the data more closely resembled a second order process. The experimental data conformed to both Langmuir and Freundlich isotherms showing that the interactions were mostly chemical in nature. The clays had reasonable monolayer adsorption capacity of 10.4, 11.9, 28.4, and 29.5 mg g^?1 for kaolinite, acid activated kaolinite, montmorillonite, and acid-activated montmorillonite respectively. Montmorillonite had much better adsorption capacity than kaolinite and the acid activation boosted the adsorption capacity of both kaolinite and montmorillonite. The interactions were exothermic in nature, accompanied by decrease in both entropy and Gibbs energy. The results have established good potentiality for kaolinite, montmorillonite and their acid-activated forms to take up and separate Ni(II) from aqueous medium through adsorption-mediated immobilization.     

磷酸活化稻壳制备柴油脱硫吸附剂

 以稻壳为原料,利用磷酸活化法制备柴油脱硫吸附剂。将二苯并噻吩(DBT)溶解在正辛烷中配制成硫质量分数300?g/g模型油,考察了纯磷酸/绝干原料质量比（磷/料比）、活化温度、活化时间及脱除二氧化硅对磷酸活化稻壳吸附剂孔结构、表面酸性质的影响以及对其DBT吸附容量的影响。实验结果表明,磷酸活化稻壳吸附剂比表面积越大,表面中等强酸性基团越多,其DBT吸附容量越大。在本实验范围内,当磷/料比为3的条件下,先在170℃下预活化1h,再在450℃活化1h,制备出的磷酸活化稻壳吸附剂的DBT吸附容量最高,以S计,达到28.89mg/g,除吸附剂脱硅后,比表面积增加, DBT吸附容量进一步增加,达到30.43mg/g。     

海泡石的热－酸活化及其对有毒化学物质的吸附效能

未活化、热活化和酸活化的海泡石在前４ｈ内对有毒化学气体的吸附速率比其本身以后的吸附速率大几到十几倍；酸活化比未活化和热活化的样品吸附作用时间增长１倍以上，吸附饱和度增大４倍左右；气源液体沸点较低而蒸气压较大者比沸点较高而蒸气压较小者，其气体被吸附量前者比后者大３倍左右；同类型的化学物质分子体积较小和形状较规则者易被吸附．     

Methylene Blue Adsorption on Natural and Modified Clays

Toxic methylene blue dye is removed from water by accumulating it on the surface of clay minerals. Clay adsorbents are obtained from kaolinite, montmorillonite, and their acid activated forms. The adsorption experiments are carried out in a batch process in environments of different pH, initial dye concentration, amount of clay, interaction time, and temperature. Adsorption of dye is best described by second order kinetics. In the temperature range of 303 to 333 K, the Langmuir monolayer capacity for three kaolinite species increased from 45.5 to 56.5 mg g^?1, 45.9 to 57.8 mg g^?1, 46.3 to 58.8 mg g^?1, and for three montmorillonites species from 163.9 to 181.8 mg g^?1, 166.7 to 188.8 mg g^?1, and 172.4 to 192.3 mg g^?1. The interaction is an endothermic process driven by entropy increase and spontaneous adsorptive accumulation is ensured by favorable Gibbs energy decrease. It is found that acid activation enhances the adsorption capacity of kaolinite and montmorillonite.     

新疆夏子街膨润土的特性及其酸活化产品脱色性能的研究

Bentonite produced in Xiazijie, Xinjiang （China） was characterized by X-ray diffraction （XRD）, differential thermal analysis （DTA）, thermogravimetric analysis （TG） and cation exchange capacity （CEC）. The bentonite is composed of dioctahedral montmorillonite with predominant quantity, certain amounts of quartz, feldspar and illite and minor amounts of kaolinite, gypsum, etc. The raw bentonite has a CEC of 0.6497 meq·g^-1 and allows to be characterized as typical sodium bentonite. In order to bleach cottonseed oil, optimum conditions for sulfuric acid activation of the raw bentonites were investigated, which were obtained by selecting various acid strength, at 96-98℃ and activating for 4h with 1 ： 2 solid-liquid ratio. The acid activation bentonites were suitable for decolorization of cottonseed oil through removing carotene and chlorophyll. The bleaching capabilities of different pigments with activated bentonite with treatment of 25% sulfuric acid were 70.3%, 73.1%, 83.2%, 81.8% and 88.9%, respectively. Bleaching with acid activated bentonite gave oils lower peroxide values and acid values.     

Calcination/acid-activation treatment of an anodic oxidation TiO<Subscript>2</Subscript>/Ti film catalyst

The aim of this work was to investigate the effects of calcination/acid-activation on the composition, structure, and photocatalytic (PC) reduction property of an anodic oxidation TiO₂/Ti film catalyst. The surface morphology and phase composition were examined by scanning electron microscopy and X-ray diffraction. The catalytic property of the film catalysts was evaluated through the removal rate of potassium chromate during the PC reduction process. The results showed that the film catalysts were composed of anatase and rutile TiO₂ with a micro-porous surface structure. The calcination treatment increased the content of TiO₂ in the film, changed the relative ratio of anatase and rutile TiO₂, and decreased the size of the micro pores of the film catalysts. The removal rate of potassium chromate was related to the technique parameters of calcination/acid-activation treatment. When the anodic oxidation TiO₂/Ti film catalyst was calcined at 873 K for 30 min and then acid-activated in the concentrated H₂SO₄ for 60 min, it presented the highest catalytic property, with the removal rate of potassium chromate of 96.3% during the PC reduction process under the experimental conditions.