Removal of basic blue 41 from aqueous solution by carboxymethylated Posidonia oceanica

The aim of this work is to improve the retention capacity already noticed for the raw Posidonia towards basic dyes and notably for basic blue 41 (BB41). To improve the fixation rate of these cationic entities, we have undertaken the introduction of carboxymethylate groups on the raw Posidonia. Thus, we have obtained materials with various carboxymethylate groups contents (from 10 to 30%). We have then studied the fixation capacities of BB41 on the different materials. We have noticed that the retention capacity of modified Posidonia was improved compared to the raw one. We have studied the effect of different parameters influencing the fixation capacities such as initial dye concentration, support dose, contact time, pH, carboxymethylate groups content, and temperature. This phenomenon of retention is compared to classic models of Langmuir and Freundlich. Some thermodynamic parameters such as free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) changes have been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1215–1225, 2007     

Transpiring wall reactor in supercritical water oxidation

Reactor corrosion and plugging problems have hindered the commercialization of supercritical water oxidation (SCWO) for wastewater purification. The use of transpiring wall reactor (TWR) is an effective means to overcome the above two problems by forming a protective water film on the internal surface of the reactor to aviod contacting corrosive species and precipitated organic salts. This work mainly aims to objectively review experimental investigations and numerical simulation results concerning TWR. Subsequent investigations for parameters optimizations of TWR are also proposed in order to ultimately build effective regulation methods of obtaining excellent water film properties. All this information is very important in guiding the structure design and operation parameters optimization of TWR.     

Degradation of reactive dyes by supercritical water oxidation in a batch reactor

The supercritical water oxidation of three reactive dyes in a batch reactor was studied with varying levels of hydrogen peroxide oxidant. The decolorisation of each dye was measured by absorbance spectrophotometry and quantitatively determined from calibration graphs for each of the three dyes. At the lowest excess oxidant concentration (zero excess), the extent of chromogen destruction was nominally lower for the red dye than for the blue and black dyes.     

Phenol oxidation in supercritical water in a well-stirred continuous reactor

A well-stirred reactor for phenol and acetic acid oxidation in supercritical water is considered. A mathematical model of an adiabatic reactor is formulated. A numerical algorithm for solving the model equations using the homotopy method is developed. The model takes into account specific features of processes under supercritical conditions, namely, the changes in the thermodynamic properties (enthalpy, heat capacity, and critical parameters) of mixtures with a change in pressure and temperature. The thermodynamic properties are calculated by methods of nonideal thermodynamics. It is shown that there is a multiplicity of steady-state solutions at various reactor performances. The results of numerical analysis of the effect of the inlet flow temperature, the amount of methanol (fuel) fed, and the total pressure on the reactor performance are presented.     

Ion exchange resins destruction in a stirred supercritical water oxidation reactor

Spent ion exchange resins (IERs) are radioactive process wastes for which there is no satisfactory industrial treatment. Supercritical water oxidation offers a viable treatment alternative to destroy the organic structure of resins, used to remove radioactivity. Up to now, studies carried out in supercritical water for IER destruction showed that degradation rates higher than 99% are difficult to obtain even using a catalyst or a large oxidant excess. In this study, a co-fuel, isopropanol, has been used in order to improve degradation rates by initiating the oxidation reaction and increasing temperature of the reaction medium. Concentrations up to 20 wt% were tested for anionic and cationic resins. Total organic carbon reduction rates higher than 99% were obtained from this process, without the use of a catalyst. The influence of operating parameters such as IERs feed concentration, nature and counterions of exchanged IERs were also studied.     

MIEX对水中DBP的去除效果及机理分析

邻苯二甲酸二丁酯(DBP)是水源水中常见的内分泌干扰物。以新型的饮用水处理材料离子交换树脂(MIEX)为吸附剂,以DBP为目标污染物,从动力学、吸附等温线、电荷密度测定、红外光谱表征、X射线光电子能谱以及共存组分影响等方面分析了MIEX去除DBP的效果和机理。MIEX去除DBP的过程仅需20 min即达到平衡,可用准二级动力学描述,中性溶液中DBP的饱和吸附量为0.944 mg·g^-1。中性条件下DBP带电量仅为2.7×10^-3 mmol·mmol^-1,MIEX与DBP间的作用并非离子交换,而是以DBP分子与MIEX基材间的疏水作用以及氢键作用为主。高浓度 和 不会对DBP的去除效果产生影响;高浓度的腐殖酸(HA)轻微抑制DBP的去除,但微量DBP并不会影响MIEX对HA的去除效果。因此,MIEX作为能高效去除水中天然有机物的新型材料,也可用于去除其中微量的DBP,适用于饮用水复合污染的处理。     

Research progress of supercritical water oxidation based on transpiring wall reactor

超临界水氧化技术的发展面临着腐蚀和盐沉积两大技术难题,采用蒸发壁反应器是解决这两大技术难题最为有效的方法。本文综述了国内外蒸发壁反应器的结构特点和性能,分析了基于蒸发壁反应器的超临界水氧化技术应用过程中仍然存在的问题,如多孔管的性能、物料的预热、系统能量利用及经济性,并提出了相应的解决办法。     

The crystal morphology of C. I. Disperse Blue 79 in supercritical carbon dioxide

The crystal growth and morphological changes of C. I. Disperse Blue 79 in supercritical CO₂ were investigated using scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. Crystals of the undissolved dye grew in the supercritical fluid and the melting point and crystallinity of this undissolved dye increased with increasing temperature and pressure.     

Kinetic study of photocatalytic decolorization of C.I. Basic Blue 3 solution on immobilized titanium dioxide nanoparticles

The photocatalytic decolorization of C.I. Basic Blue 3 (BB3) solution on immobilized TiO₂ nanoparticles was carried out in a rectangular flat-plate photoreactor. The investigated TiO₂ was Millennium PC-500 (anatase, average crystallite size 8 nm, surface area 320.76 m² g⁻¹) immobilized on non-woven paper. A new kinetic model was proposed on the basis of intrinsic element reactions. The proposed kinetic model fairly resembled the classic Langmuir–Hinshelwood (L–H) equation from its expression. It was found that both k_obs (the reaction rate constant) and K_R (the adsorption rate constant) were linearly proportional to the light intensity in a rather large intensity range.     

Removal of trace Cu from aqueous solution by foam fractionation

A system for removal of Cu²⁺ from aqueous solution by foam fractionation is proposed. The effects of pH, gas flow rate, surfactant concentration and froth/solution ratio on the removal rate and the enrichment ratio were studied to optimize the conditions. The results show that the removal rate increased with gas flow rate decreased, surfactant concentration increased and the froth/solution ratio increased, and was higher at pH4.0-5.0 than at other pH value. The optimum separation conditions were pH5.0, 200 mL/min of gas flow rate, 0.15 g/L of surfactant concentration and 1.1 of froth/solution ratio. Under the optimum conditions, the removal rate was 97.2% and the enrichment was 53.0.     

Removal of phenol from aqueous solution by liquid emulsion membrane

In the removal of phenol from aqueous solution by liquid emulsion membrane, we investigated the effect of surfactants and their concentrations, volume ratio of the internal phase to surfactant solution and sodium hydroxide concentration of the internal phase on the removal efficiency and membrane stability by using ultrasonic homogenization and mechanical stirring. Using an ultrasonic homogenizer, the highest removal was achieved at the emulsification time of 30 sec and the amplitude of 48.5 μm. The removal efficiency by the ultrasonic homogenizer was higher than that by mechanical stirring.     

Removal of textile dye from aqueous solution by electrochemical method

The use of adsorption and electrochemical treatment technologies for wastewater treatment has significantly increased in recent years. In the present study, carbon prepared from biomass waste can be used as electrode material in the electrochemical process is shown. Given that the electrode material is quite expensive, low-cost manufacturing is gaining more and more importance. Electroadsorption of textile dye (Burdem Orange II) by using activated carbon prepared from waste material, which is cherry stones, was investigated with the variation in the parameters of pH, initial dye concentration, solution flow rate, applied potential, and supporting electrolyte. The removal efficiency of textile dye up to 98% were achieved by electrochemical method.     

Removal of boron from aqueous solution by composite chitosan beads

Various metal-oxide nanoparticles and chitosan were blended to form new adsorbents (M-Oxide-CTS) for removing boron from aqueous solutions in a batch system. The maximum boron adsorption capacity (q = 7.8 mg/g) was reached at pH = 4 within 5 min. Calculations based on Langmuir, Freundlich, and Dubinin–Radushkevich models showed the heterogeneous and physical nature of boron adsorption on M-Oxide-CTS. Modeling of the thermodynamic date indicated the nonspontaneous and exothermic process. The pseudo-second-order model adequately described the boron adsorption on M-Oxide-CTS. Desorption by means of alkaline solution at pH = 12 was carried out successfully.     

Removal of aromatic amines from aqueous solution by activated sepiolite

The adsorption processes of p-toluidine, p-bromoaniline and p-acetylaniline, from aqueous solution at 20°C, on heat-treated sepiolite have been studied. With regard to the kinetic study, the processes have resulted in being second order in relation to the vacant active centres of the sepiolite, the highest value of the specific rate constant corresponding to the p-acetylaniline and the lowest one to the p-toluidine. The adsorption isotherms may be classified as L-type (Giles classification) and the values of the adsorption capacity have been calculated from the Langmuir equation applied to the experimental data points. The highest values of the adsorption capacity and specific surface area also correspond to the p-acetylaniline, and the lowest ones to the p-toluidine.     

Removal of yttrium ions from aqueous solution by ion flotation

Conditions for the concentration of yttrium from aqueous solution by ion flotation using α-sulphonated fatty acids were studied. The effects of change of collector and colligend concentration and pH, as well as the effect of interfering ions, were investigated. Maximum recovery was 99·5%.     

Removal of victoria blue from aqueous solution by fly ash

The use of fly ash for the removal of victoria blue (C126, 44045) from aqueous solution at different concentrations and pH has been investigated. The process follows first order adsorption rate expression and the rate constant was found to be 1.70 × 10^?2 min^?1 at a victoria blue concentration of 1.0 × 10^?4 M and 25°C. The uptake of victoria blue by fly ash is diffusion controlled and the value of mass transfer coefficient is 1.25 × 10^?5 cm sec^?1. The equilibrium data fit well in the Langmuir model of adsorption. Maximum removal was noted at pH 8.0. Low desorption of dye from adsorbent surface indicates that the process may not be essentially a reversible one.     

Study of transpiring fluid dynamics in supercritical water oxidation using a transparent reactor

The transpiring wall reactor (TWR) is considered to be one of the most promising reactors because it minimizes both corrosion and salt precipitation problems that seriously hinder the industrialization of supercritical water oxidation technologies. A transparent reactor is built to study the fluid dynamics of transpiring flow, which are the foundation of reactor design and optimization. The results showed that the transpiring flow is anisotropic with respect to the surface of the transpiring wall due to both the static pressure and viscous resistance. Finally, the novel idea of using air as the transpiring fluid instead of water is presented in an attempt to alleviate current TWR problems such as high energy consumption, high volume of pure water consumption, and temperature fluctuation in the reaction area. A series of experiments and theoretical derivations demonstrate that this novel idea is feasible.     

超临界水氧化/气化反应器的CFD模拟研究进展

基于前期研究和国内外相关文献,分别从数学模型、物性数据和模拟实例三个方面回溯了CFD的发展历程,综述了最新研究进展。总结出RNG k-ε、EDC分别是纯流态、湍流-化学反应两种体系普遍采用且模拟效果最好的模型,但在面对水热燃烧、水膜形成和非均相催化等典型水热过程时,仍不能有效兼顾流体力学问题与化学反应问题;其次,超临界水热环境下多相流体的基础物性数据匮乏是CFD模拟研究的另一瓶颈;最后,指出了开发新模型并结合原位探测实验新技术是未来的重点研究方向。     

Control of C.I. Basic Violet 10 aggregation in aqueous solution by the use of poly(sodium 4-styrenesulfonate)

The aggregation behavior of C.I. Basic Violet 10 in the presence of poly(sodium 4-styrenesulfonate) was modified, as a consequence of short-range interactions. In aqueous acidic media, the cationic dye forms hydrophobic ion pairs with polymeric benzene sulfonate groups which tend to aggregate in H-contacts, this tendency being readily influenced by the relative concentration of the macromolecule with respect to that of the dye. In the case of dilute aqueous dye solutions (≤10^?4 M), for which the probability of dye self-aggregation is small, C.I. Basic Violet 10 self-contacts are forced in the presence of a moderate excess of poly(sodium 4-styrenesulfonate). At dye concentrations >10^?4 M, for which the probability of dye self-aggregation increases, dye-dye contacts are minimized in the presence of a large excess of the polymer. Hence, the luminescence of dye solutions can be tuned insorar as, that of dilute dye solutions is quenched whilst that of concentrated dye solutions can be enhanced. This behavior was not observed for other polyelectrolytes such as poly(sodium vinylsulfonate), or the more hydrophobic poly(sodium 2-(N-acrylamido)-2-methyl-propanesulfonate).