Effect of Stripping Agent Type on Internal Phase Using Emulsion Liquid Membrane Method in Metal Complex Separation

Rare earth metals (REM) are scarce elements and are only found in the form of complex compounds of phosphate and carbonate. REM consists of 17 elements classified into light REM, medium REM, and heavy REM. This article is focused on lightweight REM, which is widely applied in various industrial fields. Many REM applications are increasing the demand for high-purity and bulk REMs. However, REM has almost the same physical and chemical properties, making it difficult to separate. Therefore, the separation of REM is interesting to study with various methods, one of which is Emulsion Liquid Membrane (ELM). ELM is developing a solvent extraction method involving three phases: the external phase, the internal phase, and the membrane phase. The key to the success of ELM lies in the stability of the emulsion, which is very dependent on the type and concentration of surfactants, so in the ELM process, it is necessary to choose the right concentration and type of surfactant. Therefore, this article was made to know the effect of surfactants such as span-80, span-85, and T154 in separating light REM using the ELM method.

The nuclear quadrupole interaction of dilute light rare earth (RE) metals La, Pr and Nd by time differential perturbed angular correlation measurements. The quadrupole frequency νQ has been determined in Pr as a function of temperature and pressure, in Nd as a function of temperature, and in La at 19 K. The pressure dependence of νQ of 111Cd in Pr ((d In νQ/d P)290 K = + 2.7 (2.3) · 10-3 Kbar-1) is a factor of 3 - 4 weaker than in the heavy RE metals Gd to Er. At the same time the temperature dependence of νQ in the light RE is up to a factor of 3 stronger than in the heavy RE. Between 300 K and 900 K. the quadrupole frequency is a linear function of temperature with the same slope (d In νQ/dT)290 k = - 8.4(2) · 10-4 K-1 both in Pr and Nd. Between 25 K and 300 K the decrease is stronger than linear, and more pronounced in Pr than in Nd. The temperature coefficient (d In νQ/dT)290 k is found to decrease linearly with the RE atomic number across both the series of the fight and the heavy RE metals.

The present work deals with the production of liquid emulsion membrane (LEM) accomplished by applying hydrodynamic cavitation-based process for the extraction of Chromium(VI) from wastewater. Aliquat 336 was used as the carrier during membrane transport. Diesel and Span 80 were used as diluent and emulsifier, respectively. NaOH (as a stripping agent in the internal phase) was used in emulsion preparation with the use of orifice (1 mm diameter)-based hydrodynamic cavitation process. Chromium(VI) removal from heavy metal-containing water was examined with the influence of LEM production time, amount of carrier, surfactant concentration, treat ratio (which is the ratio of feed phase to emulsion membrane phase) and type of diluent. The LEM synthesized using hydrodynamic cavitation process showed the possibility of complete removal of Chromium(VI) from the feed phase containing heavy metals, i.e. Chromium(VI). The optimal conditions were observed to be 2 min emulsification time, 1.00% carrier concentration, 3% surfactant concentration and treat ratio of 1:05. Therefore, the application of hydrodynamic cavitation for the production of LEM with excellent stability can be considered as a novel process for the extraction of Chromium(VI) from wastewater.

Investigation on liquid emulsion membrane (LEM) prepared with hydrodynamic cavitation process for cobalt (II) extraction from wastewater

Emulsion liquid membrane (ELM) process is a very promising method for the industrial separation process. This system offers many advantages, including simple operation, high selectivity, low energy requirement, and simultaneous step of extraction and stripping process. One of the most important aspects for a successful ELM process is emulsion stability, which is governed by emulsion swelling and breakage. Research on the stability of ELM system have been widely reported, especially for primary emulsion (water-in-oil) but very limited in double emulsion (water-in-oil-in-water) stability aspect. In this study, the stability of water-in-oil-in- water (W/O/W) was investigated by varying surfactant concentration of sorbitan monooleate (Span 80) and polyoxyethylene sorbitan monooleate (Tween 80), agitation speed, and agitation time. The results showed that the most stable W/O/W emulsion was obtained at 5 % (w/v) Span 80, 1 % (w/v) Tween 80, 300 rpm agitation speed, and 3 min of agitation time with no emulsion breakage or swelling occurred. This stable emulsion system can promote high extraction efficiency, which is 70 % of succinic acid was extracted.

One of heavy metal compounds that widely used in industry is Chromium. Chemical or biological treatments are not yet able to deal with the problems caused by heavy metal pollution. Taking the expensive heavy metal such as chromium, nickel, and mercury from the waste water and then re-used the recovered heavy metal is the effective method in treating waste water with expensive heavy metal on it. One of the methods that can be applied is by using Emulsion liquid Membrane (ELM).The objectives of this research were to determine the most influencing variable and to determine the optimum condition of the extraction process. The process variables tested in this research conducted were carrier concentration, external phase acidity and stripper concentration on the internal phase. While the fixed variables were ratio of emulsion and external phase volume and agitation time of the permeation step. The research was conducted in a stirred tank and divided into three major step which were the membrane stability test, the determination of the variable that gave the most dominant influence to the chromium recovery on the membrane condition which was achieved from the first step, and the third step was optimization of the most influencing variable on the chromium extraction process, while the optimum condition for the chromium extraction from liquid waste water were the concentration of chromic acid in the external phase was 600 mg/L, the stripper concentration in the in internal phase was 3 M, agitation time was 15 minutes, the volume ratio of the emulsion and the external phase was 1:3 and the carrier concentration was 0.049%. Key words : chromium, emulsion liquid membrane, extraction

A DNA-inorganic hybrid film (DNA film) was prepared by mixing DNA and a silane coupling reagent, bis(trimethoxysilylpropyl)amine. This DNA film can accumulate heavy metal ions in aqueous solution. We have demonstrated the accumulation of rare earth metal and heavy metal ions using DNA-inorganic hybrid-immobilized glass beads (DNA beads), which were prepared by coating the DNA-inorganic hybrid onto glass beads. When these DNA beads were placed in an aqueous solution of metal ions and incubated for 24 h (batch method), the DNA beads selectively accumulated heavy metal and rare earth metal ions. The maximum-accumulated amounts of Cu2+, Cd2+, In3+ and La3+ were ∼1.2, 0.94, 1.6 and 1.3 μmol, respectively, for 1 mg of DNA (3.0 μmol of nucleotide). The molar ratio of DNA to a metal ion was nucleotide:metal ion=1:0.5. Finally, we demonstrated the accumulation of metal ions by a DNA-bead column (DNA column). As a result, the DNA column effectively accumulated the heavy metal and rare earth metal ions. The DNA column was recycled by washing with an EDTA solution. DNA-immobilized glass beads (DNA beads) were prepared by coating DNA-inorganic hybrid material onto glass beads. When these DNA beads were placed in an aqueous metal ion-containing solution and incubated (batch method), the DNA beads selectively accumulated the heavy and rare-metal ions, such as Cu2+, Cd2+, In3+ or La3+. Therefore, we demonstrated the accumulation of metal ions by a DNA-immobilized glass bead column (DNA column). As a result, the DNA column effectively accumulated the heavy and rare-metal ions. Furthermore, the DNA column could be recycled by washing it with an aqueous EDTA solution.

Rare Earth Metals (REMs) are minerals which needed in modern technology because it has unique chemical, catalytic, electrical and paramagnetic properties, so REMs have the potential to be applied in various fields. The similarity in the physical and chemical properties of REMs causes them to be difficult to separate from their parent minerals. Emulsion Liquid Membrane is an effective and efficient method for REMs purification and separation because in practice it only requires a small amount of solvent, the diffusion rate and mass transfer are high, fast, and simultaneous compared to the solvent extraction method which requires many extraction steps and requires a lot of solvents. In the emulsion liquid membrane method, one of the factors that can determine the success of the extraction process is the selectivity of the ligands/extractants. The extractants must be highly selective against the target REM ions, both in the external aqueous phase and the internal aqueous phase. Therefore, this review aimed to determine the selectivity of various types of extractants such as D2EHPA, Cyanex 302, Cyanex 572, (RO)2P(O)OPh-COOH, Aniline, and TBP on extraction efficiency and stripping efficiency in the separation of rare earth metals through the emulsion liquid membrane method.

A liquid emulsion membrane (LEM) process is considered for the enrichment of nickel ions from dilute aqueous solutions. The liquid emulsion membrane consisted of a carrier di-2 ethylhexyl phosphoric acid (D2EHPA), an organic diluent, an emulsifying agent, and an aqueous stripping agent thereby having water in oil emulsion. Various stripping agents (hydrochloric, sulfuric, nitric, and methane sulfonic acid) were tested for the stability of membrane. The swelling, breakage, osmotic pressure, and particle size of LEM containing various stripping acids were compared. Methane sulfonic acid (MSA) outperformed the other acids as a stripping agent. The recovery of nickel depends on pH of aqueous feed phase. The other important variables affecting the LEM process of nickel such as acid strength, speed of agitation, organic diluent, and treat ratio were systematically investigated by using methane sulfonic acid as a strippant. It was found that nickel extraction was maximum when concentration of MSA was 1M and treat ratio was 1:3. It was also observed that dodecane as a diluent resulted in better extraction of nickel as compared to other diluents such as heptane, toluene, and xylene.

The rapid growth of industries and human activities has increased the amount of waste containing heavy metals, which are potentially toxic to human health and the environment. Conventional methods for managing heavy metal wastes have limitations, leading to the emergence of the emulsion liquid membrane (ELM) technique. This method is not only straightforward and cost-effective but also aligns with green chemistry principles. The composition of ELMs typically includes surfactants, extractants, stripping agents, and diluents. This article focuses on the use of environmentally sustainable diluents derived from vegetable oils. The diluent acts as a solvent for the extractant, aiding in the formation of a stable emulsion and reducing the percentage of emulsion breakage. This article evaluates the potential of vegetable oils as diluents in the Emulsion Liquid Membrane (ELM) process to enhance emulsion stability and the efficiency of heavy metal extraction.

From composition to performance: Evaluating the effect of emulsion liquid membrane components on lead removal from water.

Emulsion Liquid Membrane (ELM) is one of the process that has very high potential for industrial wastewater treatment of dyes. In this research, Red 3BS dye was extracted from simulated wastewater using Tridodecylamine as the carrier agent, sodium hydroxide as the stripping agent, kerosene as the diluent and span 80 was used as emulsifier. The important parameters affecting the Emulsion Liquid Membrane (ELM) extraction process including external phase concentration, treat ratio (emulsion/ external phase), concentration of carrier and agitation speed were investigated. The results show that the Red 3BS dye can be extracted almost 70% from simulated wastewater. The highest Red 3BS dye extraction was obtained by using 0.07 M Tridodecylamine, 5% (w/v) Span 80, 250 rpm agitation speed, 0.5 M thiourea in 1.0 M sodium hydroxide as the stripping agent, 1:3 treat ratio and kerosene as the diluent. As a conclusion, the Emulsion Liquid Membrane has a high potential in the extraction of dye from wastewater.

Ibuprofen (IBP) is a pharmaceutical product that is widely prescribed as an over-the-counter painkiller. It has been classified as a contaminant of emerging concern (CEC) that has received global attention in the search for a better wastewater separation technology. The emulsion liquid membrane (ELM) is one of the potential solutions for IBP removal from wastewater owing to its advantages, such as the ability to remove a highly soluble solute, energy efficient and tuneable formulation. To develop this ELM, a series of parameters such as stirring speed, emulsification time, organic to internal phase volume ratio (O/I), internal phase concentration, carrier concentration and surfactant concentration were studied. The extraction was carried out for 15 min stirring time and the concentration of IBP in the feed phase was determined using a UV-Vis spectrophotometer. The optimum formulation for the ELM was found at 300 rpm stirring speed, 20 min emulsification time, 3:1 of O/I, 0.1 M ammonia, NH3 (stripping agent), 6 wt% trioctylamine, TOA (carrier) and 2 wt% sorbitan monooleate, Span 80 (non-ionic surfactant). IBP removal of 89% was achieved at the optimum parameters of ELM. The current research demonstrated that a newly formulated ELM has great potential in removing a low concentration IBP from wastewater.

A study on the extraction of Acetaminophen (ACTP) which is also known as paracetamol, from aqueous solution by emulsion liquid membrane process using Taylor-Couette Column (TCC) was investigated. An ELM consists of three phase system which are the external, membrane and internal phases. The external phase containing the ACTP aqueous solution to be treated. Basically, the internal and membrane phase form the primary water-in-oil (W/O) emulsion using ultrasonic probe which is to be dispersed in the external phase. In this work, Trioctylamine (TOA), Span 80 and kerosene were used as carrier, surfactant and diluent, respectively in membrane phase. Meanwhile ammonia solution was used as a stripping agent in the internal phase. The influence of several operating conditions such as surfactant and carrier concentration, ultrasonic power, emulsification time, treat ratio, stirring time and stirring speed were investigated. The results showed that the present work proved that the ELM using TCC system was capable to effectively remove about 85 % ACTP from aqueous solutions under optimum conditions of 15 minutes of emulsification time, 6 wt.% of Trioctylamine and Span 80, 20 W power of ultrasonic probe, 5 minutes of extraction time, frequency angular ratio of 1.0 and treat ratio of 3:1.

Emulsion Liquid Membrane (ELM) process is one of the alternative techniques to extract solutes from wastewater. It has been given considerable attention due to its advantages such as simultaneous extraction and recovery in a single step operation, non-equilibrium mass transfer, high fluxes, low energy consumption, reusability and high selectivity. The main concern in order to achieve high stability in the process is the size of internal droplets of primary emulsion. This study aims to investigate the affecting parameters such as concentration of surfactant, emulsification speed and emulsification time. ELM process containing bis(2,4,4- trimethylpentyl) monothiophosphinic acid (Cyanex 302) as a mobile carrier in kerosene and acidic thiourea as stripping agent was used. The stability results showed that 2.8 µm of droplet diameter was formed at favorable condition of 2 % w/v surfactant concentration, 12,000 rpm of emulsification within 3 min of emulsification time. At this condition, 84 % of Palladium was extracted.