Desorption of VOC from polymer adsorbent in multistage fluidized bed

The desorption process of volatile organic compounds(VOC) from a polymer adsorbent in counter-current multistage fluidized bed was studied. And a mathematical model considering the mass transfer dynamics was developed, which was validated from experiment data. The gaseous ethyl acetate mass transfer was discussed, and the limiting step is the intraparticle mass transfer of the desorption process. The value of intraparticle mass transfer coefficient is between 1.85 × 10~(-6) and 1.38 × 10~(-5) m·s~(-1) under temperature of 100–160 °C. Experiments under different operating conditions were carried out. The effects of operating conditions such as gas–solid flow ratio,gas inlet temperature and total stage number of multistage fluidized bed on outlet VOCs concentration and desorption efficiency were discussed. The maximum outlet VOCs concentration and corresponding desorption efficiency of the multistage fluidized bed desorber was calculated under different gas inlet temperatures and total stage numbers.     

交联聚合物线团的变形能力研究

Linked polymer solution (LPS) is defined as the solution of linked polymer coils (LPCs) dispersed in water, composed of low concentration partially hydrolyzed polyacrylamide (HPAM) and aluminum citrate (crosslinker). In the work, the conformational changes of LPCs under different conditions were investigated by the methods of membrane filtering under low pressure, dynamic light scattering and core flooding experiments. The results showed that in some conditions the LPCs could be compressed mechanically to 1/158.5 of their original volume because of relatively lower HPAM cross-linking. The hydration property of LPCs was similar to that of normal polymer coils. The deformation of LPCs was more restricted than that of ordinary polymer coils under the flow shear stress or the shift of hydration equilibrium caused in the variation of the electrolyte concentration which is responsible for the effective plugging in the throats of porous media when LPCs are used for deep diverting.     

碳化钨和天然沸石复合材料在水溶液中的电催化活性(英文)

Tungsten carbide and zeolite nanocomposite was prepared by combining a mechanochemical approach with a reduction and carbonization approach,using natural zeolite and ammonia metatungstate as precursors.The sample was characterized by X-ray diffraction and scanning electron microscope.The results showed that the crystal phase of the sample is composed of zeolite,monotungsten carbide and bitungsten carbide.The mass percentage and the crystallite diameter of tungsten carbide change along with the reacted time.Its electrocatalytic activity was measured with a microelectrode system with three electrodes.The results show that its electrocatalytic property is related to its crystal phase and the mass percentage of tungsten carbide,and its electrocatalytic activity is connected with the property of electrolyte,in which it is measured.Synergistic effect between tungsten carbide and zeolite is found during electrocatalysis.     

Removal of chloride from simulated acidic wastewater in the zinc production

The removal of chloride from the zinc electrolyte produced during hydrometallurgical zinc production is challenging. The ion-exchange method is a promising way to remove chloride if the resin washing wastewater can be recycled. This paper focuses on chloride removal from resin washing wastewater to enable its reuse.Various processing factors including the oxygen gas velocity, temperature, and reaction time were investigated systematically. The results show that the optimal conditions for dechlorination are an oxygen gas velocity of 0.5 L·min~(-1), a reaction temperature of 80 ℃, and a reaction time of 30 min. A dechlorination efficiency of 80% with a residual chloride ion concentration less than 200 mg·L~(-1) was achieved, which meets the requirements for the recycling of wastewater. The presence of manganese accelerates the dechlorination by forming a Mn~(2+)–MnO_2–MnO_4~-–Mn~(2+) redox cycle. In this process, about 15 kg of the MnO_2 and all of the zinc can be recovered from 100 m~3 wastewater, and the wastewater can be reused, which makes the ion-exchange method a promising technique for chloride removal.     

氯化铜脱除硫化氢气体制硫磺研究

A novel technology of removing H2S with cupric chloride solution was developed in this paper. Cupric as the form of CuS deposition, the CuS produced was then oxidized by excessive cupric ion in another reactor meanwhile cupric ion that has been consumed can be recovered by the oxidization of with oxygen in air, and the solution can be circulated. Moreover, the leaching kinetics of CuS by cupric ion was studied. The removal efficiency of H2S is close to 100%, and the required operating condition is mild. Compared with other wet oxidiza-tion methods, no raw material is consumed except O2 in air, the process has no secondary pollution and no problem of degradation and scale, and the absorbent is much stable and reliable.     

Preparation of an amphoteric flocculant having both high polymer content and low viscosity and its polymerization kinetics

It is not easy for liquid cationic flocculant diallyldimethyl-ammonium chloride(DM) homopolymer to simultaneously exhibit both low viscosity and high polymer content, which limited its application in offshore oilfield.In this paper, sodium allylsulfonate(XS) and sodium formate were used in the aqueous solution polymerization of DM.An amphoteric flocculant(PDMXS) with the properties of high polymer content(about 55 wt%) and low viscosity(efflux time measured by an Apply 4 viscometer was less than 100 s) was prepared.The optimum reaction conditions were identified as follows: the mass ratio of XS/DM was 10 wt%, the concentration of sodium formate was 2000 mg·L~(-1), reaction temperature was 55 ℃, the concentration of KPS was 0.5 wt% and the reaction time was 4 h.The polymerization kinetics was discussed.The results showed that R_p∝ [M]~(1.97)[I]~(0.68)[CTA]~(0.71) and the apparent activation energy was 72.55 kJ·mol~(-1).     

Ghezeljeh nanoclay as a new natural adsorbent for the removal of copper and mercury ions:Equilibrium,kinetics and thermodynamics studies

Heavy metal determination was carried out by applying the solid phase extraction (SPE) method in batch mode followed by atomic absorption spectroscopy (AAS) and inductively coupled plasma atomic emission spectrosco-py (ICP-AES) from aqueous solutions using Ghezeljeh montmoril onite nanoclay as a new natural adsorbent. The Ghezeljeh clay is characterized by using Fourier Transform Infrared (FT-IR) Spectroscopy, Scanning Electron Mi-croscopy–Energy Dispersive Spectrometry (SEM–EDS) and X-ray Diffractometry (XRD) and X-ray Fluorescence (XRF). The results of XRD and FT-IR of nanoclay confirm that montmoril onite is the dominant mineral phase. Based on SEM images of Ghezeljeh clay, it can be seen that the distance between the plates is Nano. The effects of varying parameters such as initial concentration of metal ions, pH and type of buffer solutions, amount of ad-sorbent, contact time, and temperature on the adsorption process were examined. The effect of various interfer-ing ions was studied. The adsorption data correlated with Freundlich, Langmuir, Dubinin–Radushkevich (D–R), and Temkin isotherms. The Langmuir and Freundlich isotherms showed the best fit to the equilibrium data for Hg(I ), but the equilibrium nature of Cu(II) adsorption has been described by the Langmuir isotherm. The kinetic data were described with pseudo-first-order, pseudo-second-order and double-exponential models. The adsorp-tion process follows a pseudo-second-order reaction scheme. Calculation ofΔG0,ΔH0 andΔS0 showed that the nature of Hg(II) ion sorption onto the Ghezeljeh nanoclay was endothermic and was favored at higher temper-ature, and the nature of Cu(II) ion sorption was exothermic and was favored at lower temperature.     

Chemical dehydration coupling multi-effect evaporation to treat waste sulfuric acid in titanium dioxide production process

In order to concentrate the diluted sulfuric acid from the titanium dioxide(TiO_2) production of sulphate process,a new concentration process was proposed by coupling chemical dehydration and multi-effect evaporation. The ferrous sulfate monohydrate(FeSO_4·H_2O), as the dehydrant, was added to the diluted sulfuric acid to form ferrous sulfate heptahydrate(FeSO_4·7H_2O) according to the H_2SO_4-FeSO_4-H_2O phase diagrams, which partially removes the water. This process was named as Chemical Dehydration Process. The residual water was further removed by two-effect evaporation and finally 70 wt% sulfuric acid was obtained. The FeSO_4·H_2O can be regenerated through drying and dehydration of FeSO_4·7H_2O. The results show that FeSO_4·H_2O is the most suitable dehydrant, the optimal reaction time of chemical dehydration process is 30 min, and low temperature is favorable for the dehydration reaction. 45.17% of the entire removed water can be removed by chemical dehydration from the diluted sulfuric acid. This chemical dehydration process is also energy efficient with 24.76% saving compared with the direct evaporation process. Furthermore, 51.21% of the FeSO_4 dissolved originally in the diluted sulfuric acid are precipitated out during the chemical dehydration, which greatly reduces the solid precipitation and effectively alleviates the scaling in the subsequent multi-effect evaporation process.     

THE STUDY ON THE MASS TRANSFER MECHANISM OF EUROPIUM ION THROUGH LIQUID SURFACTANT MEMBRANES

The transfer of trivalent europium ion in a liquid surfactant membrane system is investigated in order toclarify the characteristics of liquid membrane separation process and the availability of this technique forrecovering trivalent lanthanides and actinides.A layered structure model for the emulsion globule is sug-gested.The equations describing the relationship among the effective membrane thickness,the time andother factors are derived and verified experimentally.Results show that under certain conditions the decreas-ing concentration of europium ion in the external phase is proportional to the square root of the time,the acidity of the internal phase and the carrier concentration in the membrane phase.The membrane phase consists of kerosene(solvent),Span-80(surfactant)and di-(2-ethylhexyl) phosphoricacid(HDEHP,carrier).The internal phase is dilute nitric acid and the external phase is aqueous solu-tion containing Eu(NO_3)_3.The mass transfer rate of europium in this system is high and the recovery ofeuropium may be more than 99%.     

乙炔法合成氯乙烯催化剂的研究进展

The synthesis of vinyl chloride is the key of polyvinyl chloride production.There are two main methods for synthesis of vinyl chloride:hydrochlorination of acetylene and oxychlorination of ethylene.The synthesis process of vinyl chloride from acetylene hydrochlorination was introduced in this paper.The research progress in novel low-mercury and mercury-free catalysts at home and abroad was reviewed.The development prospects of the catalyst for synthesis of vinyl chloride from acetylene were also outlined.     

Fouling process and anti-fouling mechanisms of dynamic membrane assisted by photocatalytic oxidation under sub-critical fluxes

Membrane fouling is often considered as a hindrance for the application of microfiltration/ultrafiltration(MF/UF) for drinking water production. A novel process of photocatalytic membrane reactor/dynamic membrane(PMR/DM), operating in a continuous mode under sub-critical flux, was proposed for the mitigation of membrane fouling caused by humic acids(HAs) in water. The mechanism of membrane fouling alleviation with synergistic photocatalytic oxidation and dynamic layer isolating effect was comprehensively investigated from the characterization of foulant evolution responsible for the reversible and irreversible fouling. The results showed that the PMR/DM utilized photocatalytic oxidation to enhance the porosity and hydrophilicity of the fouling layer by converting the high molecular weight(MW) and hydrophobic HA molecules with carboxylic functional groups and aromatic structures into low-MW hydrophilic or transphilic fractions, including tryptophan-like or fulvic-like substances. The fouling layer formed in the PMR/DM by combination of photocatalytic oxidation and DM running at a sub-critical flux of 100 Láhà1ámà2, was more hydrophilic and more porous, resulting in the lowest trans-membrane pressure(TMP) growth rates, as compared to the processes of ceramic membrane(CM), DM and PMR/CM.Meanwhile, the dynamic layer prevented the foulants, particularly the high-MW hydrophobic fractions,from contacting the primary membrane, which enabled the membrane permeability to be restored easily.     

Concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

The absorption process in acrylic acid production was water-intensive. The concentration of acrylic acid before distillation process was low, which induced to large amount of wastewater and enormous energy consumption.In this work, a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by electrodialysis. The influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale device. When the voltage drop was 1 V·cP~(-1)(1 cP=10~(-3) Pa·s), flow velocity was 3 cm·s~(-1) and the temperature was 35 °C, the concentration rates of acrylic acid and acetic acid could be 203.3% and 156.6% in the continual-ED process. Based on the experimental data, the absorption process combined with ED was simulated, in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption column. The results shown that the flow rate of spray water was decreased by 37.1%, and the acrylic acid concentration at the bottom of the tower was increased by 4.56%. The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope), membrane chemical groups(infrared spectra), ion exchange capacity, and membrane area resistance, which indicated the membrane were stable in the acid system. This method provides new method for energy conservation and emission reduction in the traditional chemical industry.     

Leaching Gold Using Oxidation Products of Elemental Sulfur in Ca(OH)2 Solution Under Oxygen Pressure

A gold leaching process by using in situ oxidation products of added elemental sulfur in Ca(OH)2 solution was investigated. A gold concentrate containing 45 g/t Au was tested and 85%~87% of gold were leached. The leached gold depends mainly on the initial molar ratio of elemental sulfur to the hydroxyl ion, the consumption of oxygen and the reaction temperature. Adding some surfactants, such as lignosulfonic calcium, at lower concentration increased the leached Au but at higher concentration decreased it. Both of thermodynamic analysis and experimental results show that thiosulfate is the major complexing agent for gold in the process.     

Degradation Kinetics of Xylose and Glucose in Hydrolysate Containing Dilute Sulfuric Acid

In preparation of fuel alcohol from biomass as feedstock, hydrolysis with dilute acid as catalyst is one way to produce fermentable saccharide, xylose and glucose. However, the acid is also the catalyst in degradation of xylose and glucose and the yield of sacchride is dependent on the kinetic behaviors of saccharide. The degradation kinetics of xylose and glucose in the hydrolysate was investigated under the conventional process conditions of hydrogen ion concentration from 0.05 to 0.2 mol/L and temperature from 150 to 200℃. With a numerical calculation method, the kinetic parameters were estimated, and the activation energy of xylose and glucose in the degradation reaction was obtained. The kinetic equations correlating the effect of hydrogen ion concentration on the rate constants of degradation reaction were established. Comparison between the calculated results from the equations and experimental ones proved that the established kinetic model could satisfactorily predict the degradation behavior of xylose and glucose in the acidic hydrolysate.     

碳酸钙在流动过冷沸腾条件下的结垢机理研究

Fouling of heat transfer surfaces during subcooled flow boiling is a frequent engineering problem in process industries. It has been generally observed that the deposits in such industrial systems consist mainly of calcium carbonate （CaCO3）, which has inverse solubility characteristics. This investigation focused on the mechanism to control deposition and the morphology of crystalline deposits. A series of experiments were carried out at different surface and bulk temperatures, fluid velocities and salt ion concentrations. It is shown that the deposition rate is controlled by different mechanism in the range of experimental parameters, depending on salt ion concentration. At higher ion concentration, the fouling rate increases linearly with surface temperature and the effect of flow velocity on deposition rate is quite strong, suggesting that mass diffusion controls the fouling process. On the contrary, at lower ion concentration, the fouling rate increases exponentially with surface temperature and is independent of the velocity, illustrating that surface reaction controls the fouling process. By analysis of the morphology of scale, two types of crystal （calcite and aragonite） are formed. The lower the temperature and ion concentration, the longer the induction period and the higher the percentage of calcite nreciDitated.     

Kinetics of Liquid-Phase Hydrogenation of Benzene in a Metai Hydride Slurry System Formed by MlNi_5 and Benzene

The kinetics of liquid-phase hydrogenation of benzene in misch metai nickel-five (MINi5) and benzene slurry system was studied by investigating the influences of the reaction temperature, pressure, alloy concentration and stirring speed on the mass transfer-reaction processes inside the slurry. The results show that the whole process is controlled by the reaction at the surface of the catalyst. The mass transfer resistance at gas-liquid interface and that from the bulk liquid phase to the surface of the catalyst particles are negligible. The apparent reaction rate is zero order for benzene concentration and first order for hydrogen concentration in the liquid phase. The kinetic modei obtained fits the experimental data very well. The apparent activation energy of the hydrogen absorption reaction of MINi5-C6H6 slurry system is 42.16kJ·mol-1.     

HIGH—PURITY WATER PRODUCTION BY RO／EDI SYSTEM

Electrodeionization(EDI),also known as continuous deionization(CDI)and packed-cell electrodialysis,is a novel hybrid separation process combining ion-exchange resin with ion-exchange membrane in one unit.The EDI process was discovered in the 1950's［1，2］in laboratory,the first commercial apparatus for the production of high-purity water was available in 1987［3］.Now the EDI technology has been found and will be continuously found its great applications in many engineering fields. In EDI,the dilute compartments are filled with mixed-bed ion-exchange resins,which enhance the transport to the membranes under the force of a direct current.The ion transport is almost entire through the ion-exchange resins and is not effected through the water.Under certain conditions,water-splitting reaction occurs in the dilute chambers and then the relative high concentrations of H+ and OH- are able to regenerate the resins continuously, With the unique “electroregeneration",the EDI unit can be considered as a mixed-bed ion-exchange column with continuous regeneration.and therefore is capable of deep deionization.Comparing with electrodialysis and ion exchange respectively,EDI has put up much superiority in water desalination. In our experiments,the processes for production of high-purity water from tap water are consisted of pretreatment (with ultrafiltration,active carbon and 10 μm-filtration),RO and EDI.     

D72树脂对镨(Ⅲ)的吸附性能(英文)

In this work, the feasibility of using a macroporous strong acid ion exchange resin (D72) as an adsorbent for praseodymium (Ⅲ) was examined. The adsorption behavior and mechanism were investigated with various chemical methods and IR spectrometry. The results showed that the loading of Pr (III) ions was strongly dependent on pH of the medium and the optimal adsorption condition is in HAc-NaAc medium with pH value of 3.0. Adsorption kinetics of Pr (III) ions onto D72 resin could be best described by pseudo-second-order model. The maximum adsorption capacity of D72 for Pr (Ⅲ) was evaluated to be 294 mg·g 1 for the Langmuir model at 298K. The apparent activation energy, E a , was 14.71 kJ·mol 1 . The calculated data of thermodynamic parameters, ΔSΘ value of 100 J·mol 1 ·K 1 and ΔHΘ value of 8.89 kJ·mol 1 , indicate the endothermic nature of the adsorption process, while a decrease of ΔGΘ with increasing temperature indicates the spontaneous nature of the adsorption process. Finally, Pr (Ⅲ) can be eluted by using 1.00 mol·L 1 HCl-0.50 mol·L 1 NaCl solution and the D72 resin can be regenerated and reused. Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design. The characterization before and after adsorption of Pr (Ⅲ) ions on D72 resin was conformed by IR.     

利用吸收-水合耦合法从氨弛放气中回收氢气的研究(英文)

In this work, the absorption-hydration hybrid method was used to recover (hydrogen + nitrogen) from (hydrogen + nitrogen + methane + argon) tail gas mixtures of synthetic ammonia plant through hydrate forma-tion/dissociation. A high-pressure reactor with magnetic stirrer was used to study the separation efficiency. The in-fluences of the concentration of anti-agglomerant, temperature, pressure, initial gas-liquid volume ratio, and oil-water volume ratio on the separation efficiency were systematically investigated in the presence of tetrahydro-furan (THF). Anti-agglomerant was used to disperse hydrate particles into the condensate phase for water-in-oil emulsion system. Since nitrogen is the material for ammonia production, the objective production in our separation process is (hydrogen + nitrogen). Our experimental results show that by adopting appropriate operating conditions, high concentration of (hydrogen + nitrogen) can be obtained using the proposed technology based on forming hydrate.