水中对硝基酚的臭氧化研究

研究了各种操作条件对臭氧降解水中对硝基酚的影响．臭氧化反应在pH=2.0和pH=5.8～12时可分别视为慢反应和拟一级快反应,由此测定出臭氧的液相体积传质系数和对硝基酚的臭氧化反应速率常数,并得到了传质系数的关联式和速率常数的Arrhenius表达式。     

强化臭氧传质的研究进展

臭氧高级氧化法具有高效、无二次污染等优势,广泛用于各类废水处理,而臭氧在气液界面传质效率低增加了运行成本.依据臭氧传质理论,从改进气液两相接触器结构、加入促传剂、外场强化等方面综述了臭氧传质的研究现状及强化机理,并展望了强化臭氧传质的发展方向.     

高压脉冲放电降解水溶液中4-氯酚过程的数学模型（Ⅱ）——鼓泡过程中臭氧传质增强因子E与4一氯酚浓度的关系

臭氧从气相传质到废水溶液中并与其中的有机污染物发生氧化还原反应是一个含有化学反应增强的臭氧吸收过程，在酸性废水中主要发生臭氧与4氯酚分子和4-氯酚盐离子的反应，而臭氧在水溶液中分解形成的羟基自由基的氧化作用可以忽略，提出了由于发生化学反应而形成的臭氧传质增强因子E与废水中有机物浓度[PCP]的定量关系的表达式．     

超重力法臭氧处理三硝基甲苯碱性废水传质模型

在前期试验研究的基础上建立了超重机中硫酸水溶液物理吸收臭氧的体积传质模型和三硝基甲苯(TNT)碱性废水化学吸收臭氧的体积传质模型。模型计算表明:硫酸水溶液物理吸收臭氧的体积传质系数为0.0191 s-1;臭氧氧化TNT碱性废水的体积传质系数在反应初始达到0.258 s-1,臭氧利用率达到93%,远高于鼓泡塔中臭氧氧化硝基苯类化合物的化学体积传质系数(0.005 88—0.017 s-1),模型的建立为以后的工业放大提供了理论依据。     

高效脱除二元酚的混合萃取剂选配

萃取脱酚是煤气化废水近零排放流程中的关键单元,萃取剂的选择是有毒二元酚资源化回收的关键步骤。工业中使用的优良脱酚萃取剂MIBK(甲基异丁基甲酮)能很好地脱除单元酚,但对于二元酚,其萃取分配系数依然较低;本文以DECHEMA数据库,通过筛选规则,以UNIFAC模型和紫外可见吸收曲线为基础,协萃系数为混合萃取剂性能指标来寻找与MIBK有协同效应的协萃剂,以提高其对二元酚的萃取性能,最终确定了新型复合萃取剂。     

静态混合器在含酚废水萃取中应用研究

使用Ｎ５０３－煤油萃取剂萃取含酚废水。总结了ＳＫ，ＳＶ两种静态混合器及组合方式的应用研究，从萃取效率，传质系数、能耗三方面确定了静态混合条件，在建立的实验装置中，确定ＳＶ混合器为最佳混合器，对实验参数进行了关联，结果发现ＳＫ，ＳＶ的传质系数Ｋ与雷诺数Ｒｅｄ１．５６成正比；ＳＫ，ＳＶ的传质系数Ｋ与能耗ΔＥ０．７成正比，并且提出利用一只静态混合器进行多级萃取的工艺过程。     

射流曝气耦合超声强化臭氧传质及应用

利用臭氧射流曝气耦合超声,探讨了操作因素对溶解O3含量与传质系数的影响,并利用超声、臭氧射流曝气、臭氧射流曝气耦合超声降解对氯苯甲酸废水。结果表明,臭氧投加量32.38 mg/L,液相、臭氧进气体积流量分别为122、50 L/h时,单独射流曝气的臭氧表观传质系数(K_La)为0.645 min^-1;引入超声后,K_La可达1.289 min^-1,表明射流曝气耦合超声可明显增强臭氧的传质效果,K_La增大了约2倍。射流曝气与超声的协同降解对氯苯甲酸废水的协同因素E可达1.546,两者具有良好的协同协应。射流曝气耦合超声是增强臭氧传质的有效方法,可为后续水处理技术提供技术支撑。     

静态螺旋切割强化臭氧液相传质研究

为解决臭氧在水中的溶解度低、应用受到限制的问题,开发了一种新型的变螺距的静态螺旋切割器,考察了臭氧气体流量、液体流量以及变螺距系数对强化传质效果的影响,并与常规曝气、循环气液喷射混合接触方式下的传质进行了对比。结果表明,在相同的时间内,液相O_3含量随着气液流量的增加而增加,变螺距系数m对于强化效果也有一定影响,采用螺距均匀变化的腔芯结构有助于臭氧在水中的溶解。采用新型螺旋切割器通气10 min后液相O_3的质量浓度可达16.2 mg/L,传质系数高达0.400 min~(-1),是相同条件下常规曝气和循环气液喷射混合方式的9.5和7.0倍。采用变螺距螺旋切割装置强化臭氧在水中的传质,能够显著提高传质速率和传质效率。     

高压脉冲放电降解水溶液中4-氯酚过程的数学模型(Ⅱ)鼓泡过程中臭氧传质增强因子E与4-氯酚浓度的关系

臭氧从气相传质到废水溶液中并与其中的有机污染物发生氧化还原反应是一个含有化学反应增强的臭氧吸收过程.在酸性废水中主要发生臭氧与4-氯酚分子和4-氯酚盐离子的反应,而臭氧在水溶液中分解形成的羟基自由基的氧化作用可以忽略.提出了由于发生化学反应而形成的臭氧传质增强因子E与废水中有机物浓度［PCP］的定量关系的表达式.     

超声波对臭氧消毒过程中传质效率影响研究

为改善污水臭氧消毒过程中臭氧传质效率低的缺点,采用超声波来提高液相中臭氧浓度及其传质效率。通过改变超声波辐射时间、功率和频率3个参数,考察其对臭氧浓度及传质效率的影响。结果表明,当超声波辐射75 s时,臭氧传质系数最大;超声波功率由0增加到110 W时,液相臭氧浓度和传质系数随功率升高而增大,当达到110W时,不再增长;传质系数和液相臭氧浓度随频率的增长而增大。     

臭氧在对硝基苯酚溶液中的吸收与模拟过程

研究了鼓泡塔中臭氧在对硝基苯酚溶液中的吸收传质过程。首先探讨了pH值和气速对对硝基苯酚降解速率的影响。在 298K下,臭氧被连续通入对硝基苯酚溶液中,臭氧的传质速率因为溶解臭氧与对硝基苯酚的快速反应而大大加强。然后运用与实验条件相同的操作参数,进行了臭氧在鼓泡塔中吸收过程的模拟研究,采用MATLAB软件求解吸收过程的质量平衡方程,模拟了吸收过程中臭氧和对硝基苯酚浓度的变化,并与实验值进行了比较。结果表明,在短的鼓泡塔中,应用全混流模型来描述气相和液相的流体状态是可行的,在 80%的对硝基苯酚降解之前,模拟值和实验值能很好地一致。     

Effect of the radical scavenger t-butanol on gas-liquid mass transfer

The alcohol t-butanol has been used as a radical scavenger in the studies of ozone reactions in water and has been found to affect the gas-liquid mass transfer rates. An understanding of the effects of t-butanol on mass transfer parameters, including bubble size, gas holdup, mass transfer coefficient and the mass transfer specific surface area, is of key importance to not only improve the knowledge of this particular system but also to gain fundamental understanding about the effects of gas/liquid surface modifiers on the contact between phases and the mass transfer rates. An experimental study has been carried out to investigate the effects of t-butanol concentrations on the physical properties of aqueous solutions, including surface tension and viscosity. It was found that t-butanol reduced both properties-by 4% for surface tension and by a surprising 30% for viscosity. These reductions in the solution physical properties were correlated to enhancement in the mass transfer coefficient, k_L. The hydrodynamic behaviour of the system used in this work was characterised by a homogeneous bubbling regime. It was also found that the gas holdup was significantly enhanced by the addition of t-butanol. An equation to predict the gas holdup from the gas flow rate and t-butanol concentration was proposed to describe the experimental data. Moreover, the addition of t-butanol was found to significantly reduce the size of gas bubbles, leading to enhancement in the volumetric mass transfer coefficient, k_La. Bubble mean diameter was predicted using an equation developed by the Radial Basis Function Neural Network architecture obtained from the literature, and the mass transfer coefficient, k_L, was predicted using an equation based on the surface coverage ratio model. The ratio was found not to depend either on t-butanol concentration or on gas flow rate. A significant increase in the volumetric mass transfer coefficient, k_La, due to an increase in both k_L and a, was obtained following the addition of t-butanol, even at low concentrations.     

INFLUENCES OF INTERFACIAL CONVECTION AND PHYSICAL PROPERTIES OF DESICCANT SOLUTIONS ON THE MASS TRANSFER PERFORMANCE OF ABSORPTION SYSTEMS

In order to investigate the mass transfer phenomenon of the absorption of water vapor in desiccant solutions, a system of absorption cell was designed. The gradient in surface tension can result from the contact process between the desiccant solution and water vapor. This induced interfacial disturbance will affect the mass transfer performance. The experimental results demonstrate that the theoretical mass transfer coefficients predicted by boundary layer theory are less than those of the experimental values. In addition, the mass transfer performance of the absorption system can be enhanced by adding ethanol to the absorbent solutions. In order to describe the level of mass transfer performance affected by the interfacial convection resulting from the addition of ethanol, the enhancement factor was defined in this study. The enhancement factor is from 1.26 to 1.56 for adding ethanol to DEG (diethylene glycol) solution, and from 1.36 to 1.61 for adding ethanol to TEG (triethylene glycol) solution.     

Mass transport effects on the electrodeposition of iron-nickel alloys at the presence of additives

Iron-nickel (Fe-Ni) plating bath solution chemistry was studied by determining the Fe-Ni equilibrium concentrations at various pH levels. It was found that the alloy composition is determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of the additives on the electrode. The effect of the rotation speed of the disc electrode and the presence of organic additives on the deposition of Fe-Ni alloys are evaluated. Boric acid increases the absolute iron deposition rate, while it inhibits the rate of nickel reduction. Saccharin and ethylene diamine influence the metal deposition rate but are not as effective as boric acid.     

梳状两亲型SMA衍生物的制备及其表面活性

通过C16～18脂肪醇聚氧乙烯醚对苯乙烯-马来酸酐共聚物(SMA)进行酯化接枝改性,制备了5个梳状两亲型SMA衍生物,即SMA-g-O-3、SMA-g-O-6、SMA-g-O-10、SMA-g-O-15和SMA-g-O-20。通过测定反应体系中原料SMA和酯化产物的酸值的变化可确定酯化反应率,其酯化率都在90%以上,且随脂肪醇聚氧乙烯醚中EO加合数的减少,酯化率相应增加,最高可达95.62%;对酯化物的水溶性及其水溶液的表面活性的研究结果表明,SMA-g-O-20的水溶性较好;25℃时,SMA钠盐水溶液降低表面张力能力有限,表面张力曲线上没有出现拐点,而改性后的SMA衍生物表面活性有较大提高,其中SMA-g-O-15水溶液的表面活性最好,其水溶液的CMC值为0.078 g/L,γCMC为26.74 mN/m。     

Correlation of hard surface detergency,soil, and surfactant

In the practical detergency range between the 90% soil removal point (the CC-1 concentration) and the point at twice the CC-1 concentration (the CC-2 point), hard surface (steel) detergency (D) is a linear function of micellar solubilization (S) such that D=K₁S+K₂, for glyceryl trioleate, oleic acid, and lauryl alcohol soils. Equations of this form were obtained for glyceryl trioleate systems using polyethenoxyethers of nonyl phenol and tridecyl alcohol, polyoxyethylene sorbitan monolaurate, sodium dodecyl benzene sulphonate, and sodium oleate. It was shown that the constants K₁ and K₂ of the detergency equation possess more than mathematical significance. Analysis of the equations for the 15, 20, and 40 ethylene oxide mole ratio adducts of nonyl phenol with glyceryl trioleate soil revealed that K₁ varied linearily with HLB of the adducts and that the K₂-log interfacial tension function (at the CC-1 point) was linear. Examination of the equations for the 20, 50, and 100 mole ratio adducts of nonyl phenol with oleic acid soil indicated also that K₁ was a function of HLB and that K₂ was a function of interfacial tension (at the CC-1 point). The detergency equations of a single surfactant (sodium dodecyl benzene sulphonate) and three soils (triolein, lauryl alcohol, and oleic acid) indicated K₁ was a function of soil dipole moment, and K₂ was a function of soil surface tension.     

A refined model for ozone mass transfer in a semibatch stirred vessel

The mathematical model proposed by Anselmi et al. (1984) for a semibatch stirred gas‐liquid contactor is refined to describe the mass transfer of ozone absorption and decomposition in aqueous solution with the decomposition rate expression of general reaction orders (not necessarily integers). Three system equations are employed to describe the ozone concentrations in the bulk liquid (C_ALb), the hold‐up gas (C_AGi), and the outlet gas in the free volume above the liquid surface (C_AGe), respectively. The effect of ozone decomposition on the mass transfer, which is reflected by the enhancement factor (E_r) defined as the ratio of mass absorbed per unit area in time t with chemical reaction (r) to that without chemical reaction or of the purely physical absorption, is considered in the refined model. Furthermore, the refined model also takes into account the variation of E_r with C_ALb, which changes with time during the course of gas‐liquid contacting. Thus this analysis extends the applicability of the model of Anselmi et al. (1984) and is of special importance for ozone mass transfer in the cases of basic solutions and of low mass transfer coefficients, in which the effect of decomposition on absorption is significant, and in the system with variable liquid phase ozone concentration.     

Experimental study on the ozone absorption accompanied by instantaneous chemical reaction

This work deals with gas absorption accompanied by chemical reaction in a liquid phase. Ozone absorption in potassium indigotrisulfonate solution was investigated in a batch bubble column. Enhancement factor for absorption accompanied by instantaneous chemical reaction in the liquid phase was experimentally determined, as a ratio of the volumetric mass transfer coefficient for the absorption accompanied by reaction to that for pure physical absorption. The influence of (a) the initial concentration of the solute from liquid phase and (b) the ozone concentration in gas phase on the enhancement factor were experimentally examined. The absorption accompanied by instantaneous chemical reaction is a diffusion-controlled process, whose rate depends upon the diffusivities of the absorbing gas and the solute in liquid phase. The influence of these diffusivities was found to be more significant for lower values of the enhancement factor. The rate of ozone absorption was followed by the time change of the solution color, using new method based on the computer program SigmaScan Pro 5 (Systat Software, Inc., San Jose, CA, USA). This investigation is a contribution to the prediction of the ozone consumption in wastewater treatment, in cases when ozone instantaneously reacts with substances present in water.     

Decomposition of 2-Chlorophenol in Aqueous Solutions by Ozone and UV/Ozone Processes in the Presence of t-Butanol

The decomposition of 2-chlorophenol in aqueous solutions by ozone and UV/ozone process was studied with the presence of t-butanol. The addition of t-butanol decreased the surface tension of aqueous solutions and subsequently increased the gas-liquid contact area. The presence of t-butanol did not affect the steady-state dissolved ozone concentration in aqueous solution; however, the ozone transfer rate between gas-liquid interface was noticeably enhanced and the time required to reach the steady state was reduced. The presence of t-butanol was found to promote the decomposition of 2-chlorophenol for both ozone and UV/ozone processes. Nonetheless, the presence of excessive dosages of t-butanol might decrease the reaction rates for experiments conducted in alkaline solutions probably because t-butanol also served as the scavenger for hydroxyl free radicals.