Degradation of phenolic compounds in water by non-thermal plasma treatment

A stainless-steel hollow needle type anode was used in the reactor to treat industrial wastewater by gas-liquid phase non-thermal plasma by corona discharge. The results showed that the short electrode gap, 1 cm, has a higher plasma energy density which improves the removal of the phenolic derivatives, reaching 100% after about 60 min. The H₂O₂ concentration was higher in the discharge system when the content of oxygen was increased. The efficiency of the phenol removal by chemical oxygen demand was only 10 – 31% after 60 minutes. The identifie dinterme diates were catechol, hydroquinone,1,4-benzoquinone, 2-nitrophenol,1,2-benzenedicarboxylic acid, diphenylmethanone, 2-methyl-hydroquinone, 2-methyl-1,4-bezoquinone, and trace amounts of organic

Toxicity of tetramethylammonium hydroxide to aquatic organisms and its synergistic action with potassium iodide

The aquatic ecotoxicity of chemicals involved in the manufacturing process of thin film transistor liquid crystal displays was assessed with a battery of four selected acute toxicity bioassays. We focused on tetramethylammonium hydroxide (TMAH, CAS No. 75-59-2), a widely utilized etchant. The toxicity of TMAH was low when tested in the 72 h-algal growth inhibition test (Pseudokirchneriellia subcapitata, EC50 = 360 mg L−1) and the Microtox® test (Vibrio fischeri, IC50 = 6.4 g L−1). In contrast, the 24 h-microcrustacean immobilization and the 96 h-fish mortality tests showed relatively higher toxicity (Daphnia magna, EC50 = 32 mg L−1 and Oryzias latipes, LC50 = 154 mg L−1). Isobologram and mixture toxicity index analyses revealed apparent synergism of the mixture of TMAH and potassium iodide when examined with the D. magna immobilization test. The synergistic action was unique to iodide over other halide salts i.e. fluoride, chloride and bromide. Quaternary ammonium ions with longer alkyl chains such as tetraethylammonium and tetrabutylammonium were more toxic than TMAH in the D. magna immobilization test

Removal of Chromium from Water Environment by Forward Osmosis System

Forward osmosis (FO) technology has been applied for removal of chromium (Cr) from water environment. Comparison of the removal efficiency of Cr(VI) and Cr(III) was investigated by changing several operational conditions. The pH of feed solution plays an important role in rejection of Cr. The Cr(VI) rejection was increased with increasing pH, while Cr(III) rejection was stable. It also demonstrated that the rejection of Cr was higher when the membrane active layer faces the feed solution compared to the rejection when the membrane active layer faces the draw solution

Solvent Extraction of Scandium and Yttrium Using Carboxylic Acid

Separation of scandium (Sc) from yttrium (Y) in aqueous chloride media by solvent extraction using Versatic acid 10 was investigated. Conventional slope analysis method revealed the extraction equilibrium formulation of the metals. Sc is more strongly extracted than Y by Versatic acid 10, and the separation factor of the metals is quite high at 1.93 × 104. Complete stripping of Sc from the loaded organic solution of Versatic acid 10 was achieved by 3M HCl solution. Then Versatic acid 10 was applied to solvent impregnated resin (SIR), separation of Sc was progressed via Langmuir adsorption model

Development of λ-MnO2 Adsorbent for Lithium Recovery from Salt Lake Brine

Lithium is widely used in industry products such as pottery or glass additives, glass flux for continuous casting of steel, grease, medicine, battery. In particular, since lithium ion batteries, which are secondary batteries, have high energy density and high voltage, recent applications have expanded as batteries for electronic devices such as laptop computers, as automotive batteries for electric vehicles or hybrid vehicles. Therefore, demand for lithium is rapidly increasing. However, in the recovery of lithium from a salt lake, brine containing many impurities such as sulfate and magnesium ions are not effectively utilized because solar evaporation cannot be used. We developed the λ-MnO2 adsorbent in order to selectively recover lithium from such brine. In this study, we investigated the adsorption characteristics such as adsorption capacity, adsorption rate and selectivity of lithium by batch mixing and column test using simulated brine. The adsorbent prepared by hydrometallurgical process had higher adsorption capacity and rate of lithium than the adsorbent prepared by pyrometallurgical process