Behavior of hydrophobic ionic liquids as liquid membranes on phenol removal: Experimental study and optimization

Room temperature ionic liquids show potential as an alternative to conventional organic membrane solvents mainly due to their properties of low vapor pressure, low volatility and they are often stable. In the present work, the technical feasibilities of room temperature ionic liquids as bulk liquid membranes for phenol removal were investigated experimentally. Three ionic liquids with high hydrophobicity were used and their phenol removal efficiency, membrane stability and membrane loss were studied. Besides that, the effects of several parameters, namely feed phase pH, feed concentration, NaOH concentration and stirring speeds on the performance of best ionic liquid membrane were also evaluated. Lastly, an optimization study on bulk ionic liquid membrane was conducted and the maximum phenol removal efficiency was compared with the organic liquid membranes. The preliminary study shows that high phenol extraction and stripping efficiencies of 96.21% and 98.10%, respectively can be achieved by ionic liquid membrane with a low membrane loss which offers a better choice to organic membrane solvents. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

Effects of operating parameters on the performance of washing–electrokinetic two stage process as soil remediation method for lead removal

The application of washing-electrokinetic two stage process on remediation of lead (Pb) contaminated soil was investigated. The process consisted of an initial soil washing, followed by an electrokinetic process. The use of electrokinetic process in soil washing could provide additional driving force for transporting the desorbed Pb away from the soil even in the absence of pore flow. Thus, high usage of wash solution may be mitigated. In this study, the effect of operating conditions such as electric potential difference, wash solution concentration and initial Pb concentration on the feasibility of washing-electrokinetic two stage process on Pb removal was investigated using response surface methodology based on Box-Behnken design. The wash solution used was citric acid and three main aspects were examined, namely: (i) removal efficiency, (ii) effluent generated, and (iii) power consumption. The results revealed that the increase in electric potential difference and wash solution concentration generally enhanced Pb removal efficiency and the interactions of these parameters were significantly positive. However, undesirable high effluent generation and power consumption were also caused by these increments. Optimisation study revealed that 84.14% removal efficiency with zero effluent generation and a power consumption of 2.27 kW h/kg Pb removed could be achieved at 7.58 V and 0.057 M citric acid concentration. In comparison with normal soil washing, washing-electrokinetic two stage process showed an enhancement in removal efficiency by approximate to 16% via electromigration under optimum conditions using similar solution: soil ratio of <0.8 mL:1 g soil. The study reveals that incorporation of electrokinetic process in soil washing is feasible as it not only enhances Pb removal efficiency at minimum wash solution usage with respect to normal soil washing, but also provides in situ Pb recovery in cathode chamber via electrodeposition. (C) 2015 Elsevier B.V. All rights reserved

Application of imidazolium-based ionic liquid as bulk liquid membrane in phenol removal / Ng Yee Sern

Performance of imidazolium-based ionic liquid membranes [Bmim][PF6], [Bmim][NTf2] and [Bmim][FAP] on phenol removal was evaluated under room temperature by using batch bulk liquid membrane system. The results showed that all ionic liquids tested formed stable membranes and exhibited better solvent recoveries in comparison to organic membrane solvent, dichloromethane with [Bmim][NTf2] showing the highest extraction and stripping efficiencies of 94.18% and 73.39%, respectively after 300 min experiment due to its relatively higher hydrogen bond basicity strength and adequate hydrophobicity. Following the finding, [Bmim][NTf2] was further analyzed to determine the effect of the feed phase pH, feed concentration, NaOH concentration and stirring speeds on liquid membrane behavior and performance. Based on the experimental results, a phenol transport mechanism which is similar to that of organic liquid membranes was proposed for [Bmim][NTf2] based liquid membrane. [Bmim][NTf2] possessed similar behavior as organic membrane solvent whereby it favoured molecular phenol extraction to phenolate anion. Besides, high phenol dissolution capacity of this ionic liquid also prevented membrane saturation even in high phenol concentration solution treatment. An optimization study on the significant parameters using Central Composite Design showed that maximum extraction and stripping efficiencies of 96.21% and 98.10% were achieved under the conditions of feed phase pH ≈6.5, 300ppm phenol concentration, 0.5M NaOH concentration, 135rpm membrane stirring speed and 255rpm aqueous stirring speed. This study has proven that [Bmim][NTf2] is a better choice than kerosene and dichloromethane

Removal of Lead from Water by Liquid-Liquid Extraction using trihexyltetradecylphosphonium Chloride in Different Diluents

The feasibility of ionic liquid trihexyltetradecylphosphonium chloride [THTDP][Cl] as extractant in different diluents for the removal of lead (Pb) from water was investigated using laboratory scale liquid-liquid extraction. The tests were conducted using an extraction mixture which consisted of 5% (v/v) [THTDP][Cl] in different diluents, namely toluene and corn oil. In general, the extraction followed anion exchange mechanism and equilibrium extraction can be achieved at extraction time of 5-10 minutes. In addition, the extraction efficiency was found to decrease when the HCl concentration in Pb solution was increased from 1 M to 3 M for both types of diluents, as a result of competition between excessive Cl- and PbCl42- to form complex with [THTDP] cation. The extraction ability of Pb for [THTDP][Cl] was highly dependent on the types of diluents used where corn oil based extraction mixture showed lower extraction efficiency in comparison to toluene based extraction mixture, as a result of its higher viscosity

Removal of Lead from Water by Liquid-Liquid Extraction using trihexyltetradecylphosphonium Chloride in Different Diluents

The feasibility of ionic liquid trihexyltetradecylphosphonium chloride [THTDP][Cl] as extractant in different diluents for the removal of lead (Pb) from water was investigated using laboratory scale liquid-liquid extraction. The tests were conducted using an extraction mixture which consisted of 5% (v/v) [THTDP][Cl] in different diluents, namely toluene and corn oil. In general, the extraction followed anion exchange mechanism and equilibrium extraction can be achieved at extraction time of 5-10 minutes. In addition, the extraction efficiency was found to decrease when the HCl concentration in Pb solution was increased from 1 M to 3 M for both types of diluents, as a result of competition between excessive Cl- and PbCl42- to form complex with [THTDP] cation. The extraction ability of Pb for [THTDP][Cl] was highly dependent on the types of diluents used where corn oil based extraction mixture showed lower extraction efficiency in comparison to toluene based extraction mixture, as a result of its higher viscosity

Remediation of Pb/Cr co-contaminated soil using electrokinetic process and approaching electrode technique

Nykypäivänä televisio, internet ja sosiaalisen median kanavat ovat täynnä terveyteen ja laihduttamiseen liittyviä aiheita. Lihavuus on yleistynyt kaikkialla maailmassa. Se kuuluu kansantautien riskitekijöihin, kuten myös epäterveellinen ruokavalio, alkoholinkäyttö, tupakointi ja vähäinen liikunta. Tutkielmassani tarkastelen Olet mitä syöt -ohjelmaa. Ohjelma keskittyy osallistujien epäterveellisiin elintapoihin ja riskitekijöihin, kuten lihavuuteen, epäterveelliseen ruokavalioon, tupakointiin ja liikkumattomuuteen. Tutkielmassani pyrin selvittämään, mitä ja miten Olet mitä syöt -televisio-ohjelmassa puhutaan elämäntapamuutoksesta, terveydestä ja laihdutuksesta. Pohdin myös sitä, miten henkilöt vastaanottavat tietoa omasta terveydestään sekä millainen asenne osallistujilla on jakson vaiheissa. Lisäksi tutkielmassani tarkastelen sitä, kuinka ohjelmassa kannustetaan tai jopa syyllistetään osallistujia. Kriittisen mediakeskustelun vuoksi selvitän myös, miten ensimmäinen ja toinen tuotantokausi eroavat toisistaan. Tutkielmani on kvalitatiivinen ja kuuluu terveyssosiologian laadullisen tutkimuksen alaan. Tutkimusaineistooni kuuluu neljä vuosien 2018–2020 aikana esitettyä Olet mitä syöt -ohjelman jaksoa. Ohjelmasta on esitetty kaksi tuotantokautta Pippa Laukan juontamana. Valitsin kummastakin tuotantokaudesta kaksi jaksoa, jotta saisin paremman kokonaiskuvan jaksoista. Aineistoni koostuu 54 sivusta litteroitua tekstiä sekä muistiinpanoista. Tutkielma-aineiston analysointiin käytän sisällönanalyysiä. Tutkimustulosten perusteella voidaan todeta, että ensimmäisen ja toisen tuotantokauden väliltä löytyy eroja sekä osallistujista että syyllisyyspuheista. Näyttää siltä, että mediakeskustelun synnyttämän kritiikin vuoksi toiselle tuotantokaudelle oli valittu erilaisista lähtökohdista tulevia osallistujia ja kauden ote oli huomattavasti lempeämpi. Ohjelman formaatti on samanlainen molemmissa tuotantokausissa. Olet mitä syöt -ohjelma etenee genrelle ominaisella tavalla ja tilanteisiin reagoitiin kuvausten edetessä. Tulevaisuudessa on tärkeää ehkäistä kansantauteihin liittyviä terveysriskejä sekä ottaa huomioon terveys- ja lihavuuspuheeseen liittyvät haasteet mediassa

Performance evaluation of two-stage electrokinetic washing as soil remediation method for lead removal using different wash solutions

<p>The study explores the application of a two-stage electrokinetic washing system on remediation of lead (Pb) contaminated soil. The process involved an initial soil washing, followed by an electrokinetic process. The use of electrokinetic process in soil washing not only provided additional driving force for transporting the desorbed Pb away from the soil but also reduced the high usage of wash solution. In this study, the effect of NaNO3, HNO3, citric acid and EDTA as wash solutions on two-stage electrokinetic washing system were evaluated. The results revealed that a two-stage electrokinetic washing process enhanced Pb removal efficiency by 2.52-9.08% and 4.98-20.45% in comparison to a normal electrokinetic process and normal washing process, respectively. Low pH and adequate current were the most important criteria in the removal process as they provided superior desorption and transport properties. The effect of chelating by EDTA was less dominant as it delayed the removal process by forming a transport loop in anode region between Pb ion and complexes. HNO3 was not suitable as wash solution in electrokinetic washing in spite of offering highest removal efficiency as it caused pH fluctuation in the cathode chamber, corroded graphite anode and showed high power consumption. In contrast, citric acid not only yielded high Pb removal efficiency with low power consumption but also maintained a low soil: solution ratio of 1 g: <1 mL, stable pH and electrode integrity. Possible transport mechanisms for Pb under each wash solution are also discussed in this work.</p