Characterization of a supported ionic liquid membrane used for the removal of cyanide from wastewater.

This work evaluated the performance of ionic liquids (ILs) in supported liquid membranes in the removal of total cyanide from wastewater. Membranes were characterized by scanning electron microscopy and contact angle measurements to study the membrane morphology and wetting ability. In particular, the effects of operational parameters such as membrane immersion time, feed-phase concentration, and pH on cyanide removal were investigated. ILs are organic salts that are entirely composed of organic cations and either organic or inorganic anions. Since their vapor pressure is negligible, they can be handled easily; this characteristic gives rise to their 'green' nature. In this study, a hydrophobic IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6), was immobilized in the pores of a solid polymeric support made of polyvinylidene fluoride. The optimal conditions were as follows: 1 hour membrane immersion time, 312.24 mg/L feed-phase concentration, a feed-phase pH of 4, 3% NaOH solution, and 1 hour stirring time. The cyanide removal was 95.31%. The treatment of cyanide using supported ionic liquid membrane (SILM) technology is a method with potential applications in industry.

Optimization of cyanide extraction from wastewater using emulsion liquid membrane system by response surface methodology.

To solve the disposal problem of cyanide wastewater, removal of cyanide from wastewater using a water-in-oil emulsion type of emulsion liquid membrane (ELM) was studied in this work. Specifically, the effects of surfactant Span-80, carrier trioctylamine (TOA), stripping agent NaOH solution and the emulsion-to-external-phase-volume ratio on removal of cyanide were investigated. Removal of total cyanide was determined using the silver nitrate titration method. Regression analysis and optimization of the conditions were conducted using the Design-Expert software and response surface methodology (RSM). The actual cyanide removals and the removals predicted using RSM analysis were in close agreement, and the optimal conditions were determined to be as follows: the volume fraction of Span-80, 4% (v/v); the volume fraction of TOA, 4% (v/v); the concentration of NaOH, 1% (w/v); and the emulsion-to-external-phase volume ratio, 1:7. Under the optimum conditions, the removal of total cyanide was 95.07%, and the RSM predicted removal was 94.90%, with a small exception. The treatment of cyanide wastewater using an ELM is an effective technique for application in industry.

Study of cyanide wastewater treatment by dispersion supported liquid membrane using trioctylamine and kerosene as liquid membrane.

A certain amount of cyanide is present in wastewater of various industrial processes, such as wet extraction of gold, coal processing, electroplating and other industries. In this work, an experimental study regarding transport of cyanide through a dispersion supported liquid membrane was performed. A model was established to describe the reaction and transport of CN(I) in the supported liquid membrane and the mass transfer kinetics equations were deduced. Through mass transfer kinetic equation it was derived that, when the carrier concentration was under certain conditions, there was a linear relationship between the reciprocal of the permeability coefficient of CN(I) (1/Pc) and n-th power of the concentration of H+ (cnH+), and the parameters Δa(δa/da) and Δo(δ0/d0) could be obtained from the slope and intercept of the straight line. Then the diffusion coefficient do and the diffusion layer thickness δo of the phase interface between the feed phase and membrane phase could be calculated. Factors affecting migration of CN(I) were analyzed, and the stable removal rate of CN(I) was more than 90% with carrier concentration (%TOA) of 2%, feed phase pH of 4, initial CN(I) concentration of 30 mg/L, stirring time of 1 hour, volume ratio of membrane solution to NaOH solution of 2:1, strip phase concentration of 2 mol/L. The results showed that the overall mass transfer rate increased first and then decreased with an increase of TOA concentration, organic-to-strip volume ratio, and strip concentration. Furthermore, the transport percentage of CN(I) was increased, the stability of membrane was enhanced, and the lifetime of the membrane was extended.

[Adsorption behaviors of protonation modified chitosan and the analysis of spectra].

In order to improve adsorbing performance and stability of chitosan in acid simultaneously, cross-linking was employed after the protection of amino groups for improving its stability, then the protection of amino groups was removed and protonated to obtain high adsorption performance. With formaldehyde as amino-group protective agent and glutaraldehyde as cross-linking reagent, cross-linked chitosan (CCTS) was prepared by reversed phase suspension method in this paper, then it was protonated to make protonation modified chitosan adsorbent (P-CCTS). The adsorption performance of sulfate ion onto P-CCTS was firstly studied and investigated by static adsorption test. Elemental analysis by energy dispersive spectrometer of X-rays (EDS) and identifying of functional groups by Fourier transform infrared spectroscopy (FTIR) were used to analyze the preparation and adsorption of the adsorbent, and the reaction mechanism of cross-linking and adsorption was investigated. The results show that the adsorption performance of P-CCTS towards sulfate ion is 10 times higher than that of unmodified chitosan, and formaldehyde and glutaraldehyde mainly react with amino (-NH2) and part of hydroxy (C6-OH) of chitosn. A salt of chitosan protonated amino chlorine was formed through the process of the protonation of amino, the adsorption of sulfate ion mainly occurs on the protonated amino on which ion exchange happened between chlorine ion and sulfate ion.

[Quantum chemical study of ultraviolet and visible spectra of four amino cobalt phthalocyanin].

Four amino cobalt phthalocyanine is well known as a promising photosensitizer. In order to enrich and complete the theoretical system of structural properties and reactivity, four amino cobalt phthalocyanine was synthesized and its ultraviolet-visible spectrum was obtained by experimental research. Then the experimental spectrum was compared with that obtained from theoretical calculation by quantum chemistry. The experimental results show that there are two obvious absorption peaks at 324.98 and 709.94 nm respectively in the ultraviolet-visible spectrum of four amino cobalt phthalocyanine. The density functional B3LYP/3-21G* method was used in simulating ultraviolet-visible absorption spectra of four amino cobalt phthalocyanine. The calculation results show that there should be two absorption peaks at 321.41 and 709.92 nm respectively. The simulation results agree well with the experimental values, which demonstrates that the density functional theory is valid and reliable in the theoretical research on four amino cobalt phthalocyanine. The contribution rate of various electron transitions in every absorption peak was determined by quantum computation. The contribution rate of various electron transition in every absorption peak was determined by quantum computation. The absorption peak at 326.22 nm is mainly resulted from electronic transition from 152 to 163 LUMO orbit, the absorption peak at 314.42 nm is due to electronic transition from 149 to 164 LUMO+1 orbit, the absorption peak at 747.57 nm is mainly caused by electronic transition from 162 to 163 LUMO orbit, and the absorption peak at 676. 01 nm is mainly caused by electronic transition from 162 to 164 LUMO+1 orbit. These data provide great theoretical complement to experimental study. The quantum chemical study for four amino cobalt phthalocyanine ultraviolet-visible spectrum has very important theoretical significance for experimental research in the future.

[Quantum chemical study of molecular structure and infrared spectra of four amino cobalt phthalocyanine].

Four amino cobalt phthalocyanine is a promising photosensitizer, so the study of its spectrum is of great significance. The density functional B3LYP/3-21G* method was used in optimizing the structure of the four configurations of four amino cobalt phthalocyanine, which can calculate the energy of its most stable structure and infrared spectra in a simulated way. It is concluded that the simulated infrared spectra and the vibration obtained from experiment are in good fitting.