Dye/water separation through supported liquid membrane extraction

Dye removal with emulsion liquid membrane: experimental design and response surface methodology

This work aims to removing anionic food dyes, Acid Red18 (E124) and Quinoline Yellow WS (E104), from their aqueous solutions. The Emulsion Liquid Membrane (ELM) technique was used. ELM consists of diluent (kerosene), nonionic surfactant (0.5 wt. % Triton X-45), Aliquat 336 as an extractant. Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters impacting the stability of liquid membrane and the efficiency of dye removal were investigated; Almost 98% of E124 at 50 mg/L are successfully extracted under optimum conditions. The extraction of a mixture of the two dyes at equal concentrations (25 mg/L) was conducted and their extraction showed more than 95% of efficiency. The experimental results of dye mixture (E124, E104) extraction were expressed by the following three quantities: The concentration of Triton X-45, the concentration of Aliquat 336, and the internal phase concentration of H2SO4, represented on three dimensional plots using the Box-Behnken design and the response surface methodology. For each of the parameters, the values of which were determined by experimental design, these results were subjected to empirical smoothing. The values, thus calculated, are consistent with the measurements.

Effects of surface morphology on alginate adhesion: Molecular insights into membrane fouling based on XDLVO and DFT analysis

While surface morphology is the key parameter affecting membrane performance, its exact roles on membrane fouling have not well unveiled. In this study, effects of membrane surface roughness on fouling caused by alginate adhesion were investigated by thermodynamic techniques of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach and density functional theory (DFT). The energy of a single typical alginate chain adhering to rough membrane surface was figured out to be 0.5-3.0 kJ/mol for the first time. Whereas, the related bending energy at typical bending angle was calculated to be over 13.0 kJ/mol based on DFT calculations. The big energy gap suggested that the alginate chain in solution would not change its configuration to fit membrane surface morphology, and tended to directly adhere to membrane surface. The thermodynamic analyses predicted that the direct adhesion pathway was favorable in energy when an alginate chain approaching to rough membrane surface. As a result, as compared to the smooth membrane, rough membrane corresponds to less alginate adhesion and adhesive fouling. Combination of XDLVO and DFT techniques provided not only molecular insights into membrane fouling, but also a new way for fouling research.

Application of edible paraffin oil for cationic dye removal from water using emulsion liquid membrane

Using an emulsion liquid membrane based on edible oils is investigated for removing cationic dyes from aqueous solutions. There is a great potential for using edible oils in food industry extraction processes. The parameters affecting the stability of the emulsion and the extraction rate were studied. These parameters were the emulsification time, the stirring speed, the surfactant concentration, the internal phase concentration, the feed phase concentration, the volume ratio of internal phase to organic phase and the treat ratio. In order to stabilize the emulsion without using a carrier, edible paraffin oil and heptane are used at an 80:20 ratio. The optimum conditions for the extraction of methylene blue (MB), crystal violet and methyl violet (CV and MV) cationic dyes using edible paraffin oil as an environment friendly solvent are represented. A removal percentage of 95% was achieved for a mixture of dyes. The optimum concentration of sodium hydroxide in the internal phase, which results a stabile emulsion with a high stripping efficiency of 96%, was 0.04 M. An excellent membrane recovery was observed and the extraction of dyes did not decrease up to seven run cycles.

Effect of hydrophobic and hydrophilic nanoparticles loaded in D2EHPA/M2EHPA - PTFE supported liquid membrane for simultaneous cationic dyes pertraction

Cationic dyes mixture pertraction experiments of Rhodamine B (RhB) and Methylene Blue (MB) using a flat sheet supported liquid membrane (SLM) were performed. Mono-(2-etylhexyl) ester of phosphoric acid (M2EHPA) and bis-(2-etylhexyl) ester of phosphoric acid (D2EHPA) mixture was used as carrier and Sesame oil to dilute the carrier due to its very high viscosity. Acetic acid (AA) was also used as stripper phase. Influences of hydrophobic and hydrophilic nanoparticles were loaded in a carrier at different loadings (from 0 to 6 mg mL^-1) on dyes pertraction at constant operating conditions were investigated. It was found that hydrophilic nanoparticles, including ZnO and TiO₂ decrease dyes pertraction, while hydrophobic nanoparticles, including ZIF-8 and Fe₃O₄ favorably increase this parameter. ZIF-8 was found as the most effective nanoparticles on increasing dyes pertraction and the optimum loading was 2 mg mL^-1. Also, the important process parameters that influence on the dyes mixture pertraction efficiency such as feed concentration, carrier concentration, feed pH and strip concentration were studied. In order to investigate the effects of operating parameters, all experiments were performed at a constant 2 mg mL^-1 ZIF-8 loading. Optimum pertraction efficiency of RhB and MB were 90.6 and 79.4%, respectively. They were obtained after 10 h pertraction at optimum experimental conditions with feed concentration of 100 mg L^-1, carrier concentration of 35% (vol), strip concentration of 0.5 mol L^-1, and feed pH of 6. Effect of time on pertraction efficiencies at the optimum conditions were also studied.

Studies on rhodamine B dye transport through a supported liquid membrane from basic aqueous solutions using phenol as a membrane phase

The aim of this work is to investigate the transport of rhodamine B across a supported liquid membrane under various experimental conditions.

Selective removal and recovery of Black B reactive dye from simulated textile wastewater using the supported liquid membrane process

Effluent containing colour/dyes, especially reactive dyes, becomes a great concern of wastewater treatment because it is toxic to human life and aquatic life. In this study, reactive dye of Black B was separated using the supported liquid membrane process. Commercial polypropylene membrane was used as a support of the kerosene-tridodecylamine liquid membrane. Several parameters were tested and the result showed that almost 100% of 70 ppm Black B was removed and 99% of 70 ppm Black B was recovered at pH 2 of the feed phase containing 0.00001 M Na2SiO3, flow rate of 150 ml/min and 0.2 M NaOH. The membrane support also remained stable for up to 36 hours under an optimum condition.

Fabrication of anion exchanger resin/nano-CdS composite photocatalyst for visible light RhB degradation

A novel nanocomposite photocatalyst, D201-CdS beads (0.70-0.80 mm in diameter), was fabricated for visible light (λ > 420 nm) photodegradation of Rhodamine B (RhB). Sphalerite CdS nanoparticles (5-15 nm) were distributed within the outer layer of D201 for favorable visible light permeation. Ultraviolet-visible spectral changes of RhB solution indicated that efficient RhB photodegradation was achieved by D201-CdS under visible light irradiation. More attractively, negligible photocorrosion of the hybrid catalyst D201-CdS was demonstrated by the constant photodegradation efficiency and negligible CdS leaching during five-cycle batch runs. Besides the higher stability, D201-CdS is superior to CdS in terms of separation. The used nanocomposite can be readily separated from solutions by a simple filtration while a high speed centrifugation is needed for the separation of CdS. The above results suggested that the resultant D201-CdS nanocomposite catalyst is promising for practical application in environmental remediation.