Effects of Wetting Agents and Approaching Anode on Lead Migration in Electrokinetic Soil Remediation

<p>Approaching anode is one of the enhancement techniques in electrokinetic soil remediation. This technique is reported to give promising migration for heavy metals under shorter treatment time and at lower cost in comparison to normal fixed anode system. In the present study, the effectiveness of fixed anode and approaching anode techniques in electrokinetic soil remediation for lead migration under different types of wetting agents (0.01M NaNO3 and 0.1M citric acid) was investigated. The study showed that the use of citric acid enhanced lead migration in comparison to NaNO3. For NaNO3 tests, lead was found to accumulate in the middle of soil section due to high soil pH, which favoured lead adsorption and precipitation. Approaching anode reduced this effect by compressed high soil pH region and enhanced lead migration at cathode region. The approaching anode only showed technical advantages when NaNO3 was used whereas the enhancement in citric acid test was insignificant. Nevertheless, this technique reduced electricity usage by 18-20% for both wetting agents.</p

Performance Evaluation of Organic Emulsion Liquid Membrane on Phenol Removal

<p>The percentage removal of phenol from aqueous solution by emulsion liquid membrane and emulsion leakage was investigated experimentally for various parameters such as membrane: internal phase ratio, membrane: external phase ratio, emulsification speed, emulsification time, carrier concentration, surfactant concentration and internal agent concentration. These parameters strongly influence the percentage removal of phenol and emulsion leakage. Under optimum membrane properties, the percentage removal of phenol was as high as 98.33%, with emulsion leakage of 1.25%. It was also found that the necessity of carrier for enhancing phenol removal was strongly dependent on the internal agent concentration.</p

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

<p>The technical feasibilities of room temperature ionic liquids as bulk liquid membranes for phenol removal were investigated experimentally.</p

Effect of Wetting Agents and Approaching Anodes on Lead Migration in Electrokinetic Soil Remediation

<p>This is the presentation slides for my conference paper "Effect of Wetting Agents and Approaching Anodes on Lead Migration in Electrokinetic Soil Remediation", which was presented in 5th International Conference on Chemical Engineering and Applications, Taipei on 27 August 2014.</p

Growth and optimization of carbon nanotubes in powder activated carbon for an efficient removal of methylene blue from aqueous solution

<p>This work demonstrated the synthesis of carbon nanotubes (CNTs) on powder activated carbon (PAC) impregnated with Ni-catalyst through chemical vapour deposition. The optimized effects of reaction temperature, time and feedstock flow rates on CNT growth were examined. Potassium permanganate (KMnO₄) and potassium permanganate in acidic solution (KMnO₄/H₂SO₄) were used to functionalize CNTs samples. A primary screening of methylene blue (MB) adsorption was conducted. The chemical, physical and morphological properties of the adsorbent with the highest removal efficiency were investigated using FESEM, EDX, TEM, BET surface area, RAMAN, TGA, FTIR, and zeta potential. The resulting carbon nanotube-loaded activated carbons possessed abundant pore structure and large surface area. The MB removal by the as-synthesized CNTs was more remarkable than that by the modified samples. Adsorption studies were carried out to evaluate the optimum conditions, kinetics and isotherms for MB adsorption process. The response surface methodology-central composite design (RSM-CCD) was used to optimize the adsorption process parameters, including pH, adsorbent dosage and contact time. The investigation of the adsorption behaviour demonstrated that the adsorption was well fitted with the pseudo-second-order model and Langmuir isotherm with the maximum monolayer adsorption capacity of 174.5 mg/g. Meanwhile, the adsorption of MB onto adsorbent was driven by the electrostatic attraction and π-π interaction. Moreover, the as-obtained CNT-PAC exhibited good reusability after four repeated operations. In view of these empirical findings, the low-cost CNT-PAC has potential for removal of MB from aqueous solution.</p

Generation of Superoxide Ion in Pyridinium, Morpholinium, Ammonium, and Sulfonium-Based Ionic Liquids and the Application in the Destruction of Toxic Chlorinated Phenols

Generation of superoxide ion (O₂^•–) was carried out in four ionic liquids (ILs) having the same anion, bis­(trifluoromethylsulfonyl)­imide [N­(Tf)₂]⁻, and different cations, N-hexylpyridinium [HPy]⁺, N-methoxyethyl-N-methylmorpholinium [MO1,1O2]⁺, N-ethyl-N,N-dimethyl-2-methoxyethylammonium [N112,1O2]⁺, and triethylsulfonium [S222]⁺. Cyclic voltammetry (CV) and chronoamperometry (CA) electrochemical techniques were used in this investigation. It was found that O₂^•– is not stable in the [HPy]⁺-based IL. On the other hand, CV showed that the electrochemically generated O₂^•– is stable in [MO1,1O2]⁺-, [N112,1O2]⁺-, and [S222]⁺-based ILs for the time duration of the experiment. The long-term stability of the generated O₂^•– was then investigated by dissolving potassium superoxide (KO₂) in dimethyl sulfoxide (DMSO) in the presence of the corresponding IL. It was found that ILs containing [MO1,1O2]⁺ and [N112,1O2]⁺ offer a promising long-term stability of O₂^•– for various reactions to be used for several applications. However, it was found that after 2 h, about 92.5% of the generated O₂^•– in [S222]⁺ based IL was consumed. The diffusion coefficient and solubility of O₂ in the studied ILs were then determined using CV and CA techniques simultaneously. It was found that diffusion coefficients and CA steady-state currents increase with temperature increases, while the solubility of O₂ decreased. To our best knowledge, this is the first time that morpholinium and sulfoniumbased ILs were utilized as media for chemical and electrochemical generation of O₂^•–. Additionally, the chemically generated O₂^•–, by dissolving KO₂, was then used for the destruction of 2,4-dichlorophenol (DCP) in [MO1,1O2]­[N­(Tf)₂] under ambient conditions. The destruction percentage was higher than 98%. This work represents a novel application of the chemically generated O₂^•– for the destruction of toxic chlorinated phenols in ILs media

Evaluating the Performance of Deep Eutectic Solvents for Use in Extractive Denitrification of Liquid Fuels by the Conductor-like Screening Model for Real Solvents

A total of 94 deep eutectic solvents (DESs) based on different combinations of salt cation, anion, hydrogen-bond donor (HBD) and salt:HBD molar ratio are screened via the conductor-like screening model for real solvents for potential use in the extractive denitrification of diesel. Five nonbasic and six basic nitrogen compounds were included in this study. The activity coefficient at infinite dilution, γ^∞, of each nitrogen compound in the DESs was predicted; and the values are used to screen the DESs on the basis of selectivity, capacity, and performance index at infinite dilution (<i>S</i>^<i>∞</i>, <i>C</i>^<i>∞</i>, and PI). The extraction of nitrogen compounds using DES is driven by hydrogen-bonding interaction. It was found that nonbasic compounds report higher <i>S</i>^<i>∞</i> and <i>C</i>^<i>∞</i> than basic compounds. Ammonium-based DESs give higher <i>S</i>^<i>∞</i> but phosphonium-based DESs report higher <i>C</i>^<i>∞</i>. DESs combined with Cl^– anion give higher <i>S</i>^<i>∞</i>, but those with Br^– anion report higher <i>C</i>^<i>∞</i>. DESs with alcohol- and amide-based HBDs give higher <i>S</i>^<i>∞</i> but HBDs with carboxylic acid group report high <i>C</i>^<i>∞</i>. Molar ratio has little effect toward <i>S</i>^<i>∞</i> and <i>C</i>^<i>∞</i>. DESs with high values of <i>S</i>^<i>∞</i> generally have high PI

Numbering of DESs, their individual constituents and aqueous solutions.

<p>Numbering of DESs, their individual constituents and aqueous solutions.</p

Structures of the salt and HBDs.

<p>Structures of the salt and HBDs.</p

Antioxidant capacity of the DESs by ORAC method.

<p>Antioxidant capacity of the DESs by ORAC method.</p