Membrane-based Solvent Extraction Research Articles

Life cycle assessment of zinc and iron recovery from spent pickling acids by membrane-based solvent extraction and electrowinning.

In this paper we conducted a life cycle assessment to evaluate the environmental performance of the valorization of spent pickling acid (SPA) generated in the hot-dip galvanizing (HDG) process. We analyzed the environmental impacts of treating one m3 of SPA, comparing the reference treatment consisting of neutralization, precipitation, stabilization, and landfilling of the metallic sludge (scenario #1), with the innovative LIFE2ACID technology (scenario #2) that produces secondary zinc and iron chloride in solution through non-dispersive solvent extraction (NDSX) and electrowinning (EW). The results showed that the materials credits achieved by the implementation of LIFE2ACID technology turned most of the impact categories evaluated (toxicity, acidification, eutrophication, ozone depletion, etc.) into environmental benefits. Scenario #2 was adapted to achieve either zinc-only recovery (#2.1) or simultaneous iron and zinc recovery (#2.2). The abiotic depletion potential (ADP) of fossil fuels increased slightly from scenario #1 to scenario #2.1 because of the higher energy demand and NaOH consumption of EW, and because only zinc was recovered. However, the valorization of both zinc and iron chloride in scenario #2.2 reduced the ADP-fossil by 27%, compared to the reference treatment. Furthermore, the global warming impact was reduced by 20% and 97% in scenarios #2.1 and #2.2, respectively. With the focus on promoting the circular economy concept, we conclude that the LIFE2ACID technology significantly improves the environmental performance of SPA management. Next steps should consider the life-cycle costs analysis in specific scenarios to find out the trade-off between environmental and economic objectives.

Intensificación de la producción de 2-feniletanol empleando un sistema aireado asistido por una técnica de extracción de una membrana basada en solvente

The production of 2-phenylethanol (2-PE), a high-valued aroma, has been performed naturally through the bioconversion of L-phenylalanine by the Ehrlich pathway in yeast. Nevertheless, one of the main limitations of this bioconversion is the inhibition of yeast growth by 2-PE. This work evaluated the intensification of 2-PE production in a batch culture using a conventional bioreactor coupled to an in-situ product removal (ISPR) process, by means of membrane-based solvent extraction (MBSE). The culture of the native yeast Kluyveromyces marxianus ITD0090, using a shaker flask stirred at 150 rpm, produced a maximum concentration of 2-PE of 0.7 g L-1 after 24 hours. When the yeast was cultivated in a controlled aerated-stirred bioreactor operated at 0.8 vvm and 350 rpm, the maximum production of 2-PE after 48 h reached 1.49 g L-1. Intensification of the bioprocess was achieved by coupling the controlled bioreactor with a MBSE system, which allowed the continuous recovery of the 2-PE produced, reaching a final titre of 3.02 g L-1 after 56 h.

Scale-Up of Membrane-Based Zinc Recovery from Spent Pickling Acids of Hot-Dip Galvanizing.

Zinc recovery from spent pickling acids (SPAs) can play an important role in achieving a circular economy in the galvanizing industry. This work evaluates the scale-up of membrane-based solvent extraction technology aimed at the selective separation of zinc from industrial SPAs as a purification step prior to zinc electrowinning (EW). The experiments were carried out at a pilot scale treating SPAs batches of 57 to 91 L in a non-dispersive solvent extraction (NDSX) configuration that simultaneously performed the extraction and backextraction steps. The pilot plant was equipped with four hollow fiber contactors and 80 m2 of total membrane area, which was approximately 30 times higher than previous bench-scale studies. Tributylphosphate diluted in Shellsol D70 and tap water were used as organic and stripping agents, respectively. Starting with SPAs with high Zn (71.7 ± 4.3 g·L−1) and Fe (82.9 ± 5.0 g·L−1) content, the NDSX process achieved a stripping phase with 55.7 g Zn·L−1 and only 3.2 g Fe·L−1. Other minor metals were not transferred, providing the purified zinc stripping with better quality for the next EW step. A series of five consecutive pilot-scale experiments showed the reproducibility of results, which is an indicator of the stability of the organic extractant and its adequate regeneration in the NDSX operation. Zinc mass transfer fluxes were successfully correlated to zinc concentration in the feed SPA phase, together with data extracted from previous laboratory-scale experiments, allowing us to obtain the design parameter that will enable the leap to the industrial scale. Therefore, the results herein presented demonstrate the NDSX technology in an industrially relevant environment equivalent to TRL 6, which is an essential progress to increase zinc metal resources in the galvanizing sector.

Computational modelling of separation and purification of vanillin using microporous membranes

In this study, membrane based solvent extraction of vanillin as one of the most popular flavour was investigated theoretically using computational fluid dynamic technique. A mass transfer model and simulation was developed based on continuity and transport phenomena equations. The effect of operating parameters such as pH, type of solvent and feed flow rate as well as membrane specifications including fibres number, fibre length and porosity-to tortuosity ratio was investigated. There was good agreement between experimental data and modelling value in terms of vanillin extraction percentage. The results showed that butyl acetate is the best solvent and it had the highest vanillin extraction at pH of 7. It was found that increasing feed flow rate can decrease vanillin extraction due to reduction of residence time in the contactor. Change in the membrane specifications had positive impact on the vanillin extraction. Increase in all fibres length, number of fibre, and porosity-to tortuosity ratio because of improving residence time, mass transfer area, and increase in effective diffusivity, respectively led to the enhancement of vanillin extraction. The extraction was reached 44% when the fibre length became 5 times longer. Moreover, it was concluded that the membrane system showed better performance when the feed flows in the tube side of contactor.

Cobalt–Nickel Pertraction Refinery to Process Pregnant Leach Solution from Recycled Spent Catalysts Part 1: Cobalt Extraction from a Binary System

ABSTRACT Owing to the recent increase in the global demand for Co, new cobalt–nickel refinery capacity is required. While solvent extraction is one of the most important separation and purification techniques in hydrometallurgy, pertraction, also called membrane-based solvent extraction, offers various advantages over conventional solvent extraction. In this study, pertraction was used to purify a pregnant leach solution obtained from spent hydrotreatment catalysts that had been produced by Minemet. A block flow diagram and mass balance for the cobalt–nickel refinery were developed and used in the experimental design. Extraction isotherms were determined as well as mass transfers optimised using a circulating batch pertraction setup for both synthetic and industrial cobalt–nickel mixed metal solutions. A comprehensive set of models was applied to translate the experimental data into a conceptual design of the industrial cobalt–nickel pertraction refinery to process pregnant leach solution from the Minemet plant.

Electroplating wastes

AbstractElectroplating and other metal finishing industries, like every metal and metallurgical industry, are associated with the generation of waste. Spent electroplating baths, waste pickle liquors, etching solutions and rinse waters from electroplating units and steel finishing operations are complex solutions containing acids and several hazardous metals. It is compulsory, for environmental and economic reasons, to treat these solutions for recovering acid, metals and/or reusing these solutions/waters. This article is a review on the characterization of the wastes that are generated in electroplating industry, steel processing and copper etching in printed circuit boards manufacture, as well as on the treatment and regeneration methods of such streams. Various techniques, such as neutralization, crystallization, evaporation, pyrohydrolysis, electrodialysis, ion exchange, classical solvent extraction and membrane-based solvent extraction are presented, their advantages and disadvantages being scrutinized.

Membrane selective recovery of HCl, zinc and iron from simulated mining effluents

This work proposes a flowsheet based on the combination of membrane processes for the effective recovery of value-added components contained in mining effluents with high concentration of hydrochloric acid and metal anionic and cationic chloro-complexes. A representative case of study has been selected consisting of a solution of zinc and iron that under the studied conditions were solubilized forming anionic and cationic chloro-complexes. The high complexity of the system requires of a selective membrane-based solvent extraction step to successfully achieve the separation of cationic iron from a solution containing the acid together with anionic species of zinc followed by a diffusion process through ion conductive membranes for acid recovery; in this step electrodialysis was selected searching for the optimum trade-off between process kinetics and separation selectivity. Although the quantitative results are case-dependent, the methodology can be well extended to any mining leaching effluent coming from the use of HCl as leaching agent and containing metal chloro-complexes.

Quasi-dynamic modeling of dispersion-free extraction of aroma compounds using hollow fiber membrane contactor

The current work focuses on the membrane-based solvent extraction of aroma solutes through computational modeling and simulation. A 2D mathematical model was presented to study the extraction of four selected aroma compounds namely, dimethyltrisulfide (DMTS), ethyl butyrate (EB), benzaldehyde (BA) and 2-phenyl ethanol (PE). These compounds were recovered from aqueous solutions with hexane as an organic solvent in hollow fiber membrane contactor (HFMC). Model equations were developed by applying mass and momentum balances across HFMC. Momentum balance equations were coupled with continuity equations using computational fluid dynamics (CFD) technique for the investigation of solutes’ concentration in three sections of the membrane module. Simulation results were validated using experimental data for the extraction of all four selected aroma compounds and a good agreement was found. The simulation was then run to study the effects of hydrodynamics on extraction. It was found that extraction efficiency for DMTS, EB, and BA almost doubled when the flow rate was decreased to one-fourth. Furthermore, the study revealed that CFD can be effectively applied for the optimum design of membrane-based extraction processes.

Evaluation of Esterification and Membrane Based Solvent Extraction as Methods for the Recovery of Short Chain Volatile Fatty Acids from Slaughterhouse Blood Anaerobic Mixed Fermentation

Two routes, esterification and membrane based solvent extraction, were tested for their efficiency to extract volatile fatty acids (VFA) (acetic, propionic, butyric, iso-butyric, iso-valeric and valeric acids) produced from the anaerobic-mixed fermentation of slaughterhouse blood. A range of operational parameters and reagents were assessed to optimize each system. Esterification recovered VFA as methyl esters with the production of ammonium sulphate as a value-added by-product of the esterification reaction. A membrane extraction system, comprised of a hydrophobic membrane and extractant using octanol/TOA (trioctylamine), was efficient to separate butyric and iso-valeric acids in favour of acetic acid from the fermentation broth. These results provided important information for the development of a carboxylate-platform bio-refinery using high-protein wastes as substrate.

Automation of membrane based solvent extraction unit for Zr and Hf separation

Abstract In recent years, research into metal ion solvent extraction using hollow fibre membranes has grown. Current studies generally use an analogue controlled experimental setup. Although the analogue system is sufficient for initial proof of concept studies, it does lack the accuracy and repeatability to advance this technology to the next step of commercialization. The aim of this study was therefore to design and construct an automated membrane based solvent extraction system for use in Zr and Hf extraction research. The objective was to attain independent automated control of flow rate and pressure, while improving the accuracy and repeatability of extraction results. Flow rate and pressure were controlled using PID control algorithms and optimized using the Cohen-Coon tuning method. After optimization, a case study for the extraction of Zr and Hf, using Cyanex 301® as extractant, was conducted. It was shown that the automated system was able to accurately control the flow rate and pressure. This improvement of accuracy led to highly reproducible extraction results with the standard deviations varying by less than 1.2%. From this it can be concluded that the automated system was successfully implemented with independent control of the flow rate and pressure.

Uranium recovery from simulated molybdenum-99 production residue using non-dispersive membrane based solvent extraction

Commercial alkaline dissolution molybdenum-99 (99Mo) producers are currently not recovering enriched uranium (U) from 99Mo production waste which has a unique actinide and fission product composition. During the development of a process to recover U from 99Mo production residue, the suitability of non-dispersive membrane based solvent extraction (MBSX) for this process was investigated. The residue was dissolved in nitric acid (HNO3) and extracted using tributyl phosphate (TBP). Acetohydroxamic acid (AHA) was added to the feed to prevent co-extraction of plutonium (Pu). Complete U extraction with MBSX was achieved at low U(VI) concentrations in the feed while more than one MBSX contacting step was required for high U(VI) concentrations. Ammonium carbonate ((NH4)2CO3) was investigated as an alternative stripping solution to traditionally used dilute HNO3. Almost complete U(VI) stripping (99%) from 7500mgL−1U(VI) in the organic phase was obtained in a single contacting step with 0.5M (NH4)2CO3. Practically none of the characteristic fission products present in the 99Mo production residue were extracted with AHA and also neither influencing U(VI) nor fission product extraction. The study has shown that MBSX was suitable for selective extraction (with AHA added) and stripping (0.5M (NH4)2CO3) of U(VI) from a simulated 99Mo production residue.

Selective recovery of zinc from spent pickling baths by the combination of membrane-based solvent extraction and electrowinning technologies

This work deals with the analysis of an integrated zinc recovery process by means of electrowinning of the stripping solutions coming from the treatment of spent pickling baths (SPB) by a membrane-based solvent extraction (MBSX) process able of increasing the initial Zn/Fe molar ratio. Several stripping solutions containing different concentrations of zinc and iron in acid media obtained previously by the treatment of SPB by MBSX, were subjected to electrowinning to assess the efficiency and selectivity of zinc electrodeposition over iron under different operation conditions.At similar values of the zinc concentration in the stripping solution, the influence of the Zn/Fe molar ratio on the zinc electrodeposition process was negligible. On the other hand, although the variation of the initial concentration of zinc in the stripping solution neither affected the efficiency of zinc electrowinning, it increased the minimum value of zinc concentration in solution beyond which iron co-deposition started. Finally, the increase in the applied current, promoted the increase in zinc fractional conversion and in the zinc space–time yield, while the zinc current efficiency was reduced due to the stronger effect of secondary reactions.Although the change in the stripping characteristics seems not to strongly affect the zinc electrodeposition process, the use of a pretreatment step based on MBSX technology improved the results in terms of zinc percentage recovered and the rest of figures of merit, in comparison with those obtained by the direct electrowinning of SPB.

Selective Recovery of Zinc over Iron from Spent Pickling Wastes by Different Membrane-based Solvent Extraction Process Configurations

This paper reports the selective separation of zinc over iron from spent pickling wastes or effluents using two different membrane-based solvent extraction process configurations, Nondispersive solvent extraction (NDSX) and emulsion pertraction technology (EPT). The process aims to obtain a highly concentrated zinc solution with a negligible content of iron to allow for Zn electrowinning. The effect of the following process variables on the kinetics and selectivity of zinc separation has been evaluated: (i) process configuration NDSX and EPT, (ii) extractant concentration, tributylphosphate (TBP) in the range of 20–100% v/v and (iii) stripping phase/feed phase volume ratio in the range Vs/Va 0.2–2. The transport of iron, chloride and free acid has been also monitored to gain insight into the separation fundamentals. EPT configuration overcame NDSX in terms of zinc and iron separation kinetics, although separation selectivity (at 30 min) was higher for NDSX configuration, αZn/Fe = 22, compared to EPT proce...

ChemInform Abstract: Phenol Removal from Industrial Wastewaters: A Short Review

AbstractReview: 138 refs.

The possibility of membrane-based solvent-extraction (MBSX) as a separation method for Zr and Hf in aqueous solutions

The possibility of membrane-based solvent-extraction (MBSX) as a separation method for Zr and Hf in aqueous solutions. The focus of this study was to determine the suitability of this MBSX technology to purify and simultaneously concentrate Zr. It is known that Zr and Hf possess inherently slow chemical kinetic properties. However, by optimising the design and the operating conditions, we succeeded in removing Hf from the Zr solutes, while almost completely recovering the desired Zr.

Phenol removal from industrial wastewaters: a short review

The toxicity of phenol even at low concentrations in industrial effluents is high enough to meet its needs for separation. In this paper, a review will be carried out on the traditional techniques and recent advances in the separation of phenol from its contaminated streams. The most commonly used methods classified based on the phenol concentrations (high, medium, and low), and also, their advantages and disadvantages that should be considered in the design of industrial wastewater treatment systems will be discussed. Finally, the best methods will be suggested for each concentration range at the influent and, of course, that is allowable in the final effluent. The survey results recommended that biodegradation, chemical, electrochemical, and photocatalytic oxidation, solid phase extraction, ozonation, reverse osmosis/nanofiltration, and wet air oxidation are useful methods in low phenol concentrations, whereas liquid–liquid extraction, pervaporation, membrane-based solvent extraction, adsorption, and distillation are suggested for high phenol concentrations.

Investigation of 2-phenylethanol production in fed-batch hybrid bioreactor: Membrane extraction and microfiltration

Bioconversion of l-phenylalanine to 2-phenylethanol using Saccharomyces cerevisiae is connected with the growth of biomass which is strongly limited by product inhibition. Therefore, fermentation can proceed only at low conversions of l-phenylalanine with very low yield of the desired product. Maximal concentration of 2-phenylethanol in an ordinary batch, fed-batch or chemostat bioreactor achieves the values of about 4gL−1. The main aim of the present work was to study possible yield increase achieved by continuous separation of 2-phenylethanol such as membrane based solvent extraction (membrane extraction) and cross-flow microfiltration interconnected with a bioreactor in one hybrid system. In this part of the research, membrane extraction of 2-phenylethanol from aqueous phase to alkanes was examined using two different types of hollow fiber membrane modules. The measured extraction kinetics was compared with that obtained by the mathematical model of the membrane extraction at different operational parameters using the partition coefficient of 2-phenylethanol determined by equilibrium experiments. The air-lift reactor was connected with a ceramic multi-channel microfiltration module to study the impact of feed pumping to the microfiltration unit on the air-lift reactor hydrodynamics as well as the influence of different values of biomass concentration, transmembrane pressure, cross-flow velocity and bubbles dragging in the microfiltration unit on the steady-state permeate flux.

Simulation of a new regeneration process of solvents with ionic liquid by short-path distillation

A new promising process for the regeneration of solvents with ionic liquid (IL) by short-path distillation (SPD) has been proposed and its application potential analyzed by simulation. Main advantage of this process compared to classical stripping with alkali solution is that the product is in form of free acid, not its salt and the consumption of chemicals is reduced. The model loaded solvent with phosphonium IL from membrane based solvent extraction (MBSE) of butyric acid (BA) was regenerated by two stage SPD at the temperature of 130 and 160°C and pressure of 13 and 2kPa, respectively. SPD was combined with extraction of BA from the dodecane phase of distillates by water. Yield of BA in distillates was 89%. The concentration factors of BA in both concentrates compared to BA concentration in the fermentation broth were of 25 and 43, respectively, for the dodecane content in the dry solvent containing 70 mass% of IL. Overall theoretical heat consumption in SPD was 3410kJperkg of recovered BA. The simulation has shown that both the yield of BA in MBSE and the mass flux of the solvent in MBSE are strongly influenced by the residual content of BA in recycled dodecane after the extraction of BA. Both parameters play a key role in the process performance. Additional experimental data on MBSE, SPD and dodecane extraction are needed for design and optimization of the hybrid process.

Membrane contactors (NDSX and EPT): an innovative alternative for the treatment of effluents containing metallic pollutants

This work presents an overview of membrane-based solvent extraction technologies using membrane contactors as an innovative alternative for the remediation of effluents containing metallic pollutants. The discussion is focused on the description of Non-Dispersive Solvent Extraction (NDSX) and Emulsion Pertraction Technologies (EPTs). Three case studies are reported to demonstrate the viability of NDSX and EPT for the removal and recovery of metallic pollutants present in aqueous streams:

Experimental and theoretical considerations on breakthrough pressure in membrane-based solvent extraction: Focus on citrus essential oil/hydro-alcoholic solvent systems with low interfacial tension

The aim of this work was to select materials to facilitate interface stabilisation in membrane contactors in order to apply membrane-based solvent extraction to systems with low interfacial tension. For this purpose, polymeric and/or ceramic porous membranes able to achieve a robust stabilisation of the liquid–liquid interface were selected (breakthrough pressure higher than 0.5 bars). The case study considered was the recovery of highly valuable oxygenated terpenes from lemon essential oil in an aqueous solvent containing up to 80% v/v ethanol. Wetting of membranes and contact angle measurements were performed in order to select materials with a minimal affinity for the hydro-alcoholic mixtures. Eight flat sheet membranes differing as to type of material and structure were investigated at 25 °C. The membrane–solvent combinations were carefully chosen since properties of both liquids and membrane materials determine the breakthrough pressure ΔP c, which could be interpreted using the Young–Laplace equation. Experimental determination of ΔP c under process conditions showed that very hydrophobic membranes (polytetrafluoroethylene or grafted ceramic) with a maximum pore size of 160 nm led to satisfying breakthrough pressures of up to 0.98 bars for solvents containing 40% v/v ethanol. This study identified the requirements in terms of both the type of material and the structure of membranes necessary to increase the interface stability, thus: (i) making it possible to recover target molecules from complex systems such as essential oils; (ii) extending the range of solvents that can be used; and (iii) making process control much easier and more robust.