Seban Lee

Sonochemical Oxidation of Arsenite in Aqueous Phase

The objective of this research is to assess critically the experimental rate data for sonochemical oxidation of arsenite [As(III)] at different frequencies and powers in the aqueous phase. The oxidative conversion of As(III) into arsenate [As(V)] was >90% in the range of 283 to 450 kHz. With a power density of 69 W L-1, the oxidation of As(III) for 40 min at 283 kHz showed a second-order rate constant of 7.1×102 M-1 s-1, whereas it was 3.8×103 M-1 s-1 at 450 kHz. As calculated by the calorimetric method, the power transferred into samples was in the range of 7–34.5 W with the two frequencies of 283 or 450 kHz. Approximately 100% oxidation efficiency was obtained with a frequency of 450 kHz and 34.5 W. As the pretreatment process, oxidation by sonication has potential applications to groundwater contaminated with both As(III) and As(V).

Arsenite Oxidation and Treatment by Ultrasound/Iron in Aqueous Solutions

The oxidation and treatment of arsenite [As(III)] with ultrasound (US) and Fe(II) was investigated in aqueous solutions. The oxidation of As(III) into As(V), over 99.1%, was obtained by US450kHz. The kinetics of As(III) oxidation were interpreted using the modified pseudo-first-order kinetic model. The half life of As(III) was approximately 3.47 ×10-2 s for the US450kHz/Fe(II)0.4mg/L reaction and depended on the iron concentration. The arsenic removal capacity of complexed and coprecipitated FeAsO4(s) was estimated to be 16.12 mg per g of iron oxide. It is concluded that the sonochemical treatment of As(III) solution in the presence of Fe(II) is a simple and viable technique for the oxidation of As(III) into arsenate [As(V)] and the treatment of total arsenic.

Sonochemical oxidation of cyanide using potassium peroxydisulfate as an oxidizing agent

In this study, the sonochemical oxidation of cyanide in the presence of peroxydisulfate (PDS) ions has been investigated. As a result of experiments, sulfate anion radicals (SO4-) and hydroxide radicals (OH) produced by PDS ions in acoustic cavitation could readily oxidize and even mineralize cyanide in an aqueous environment. When the frequency of ultrasound and PDS ions were applied at 450 kHz and 60 mgL-1, the efficiencies of mineralization for free cyanide (CN-) and thiocyanate (SCN-) were 99.3 and 99%, respectively. The kinetics of total organic carbon (TOC) reduction for CN- and SCN- oxidation were interpreted using the modified pseudo-first-order kinetic model. In this study, carbonate and nitrate were found to be by-products of CN- oxidation while sulfate, carbonate and nitrate were by-products of SCN- oxidation.

A Study of Kinetics and Adsorption Characteristics for Removal of Arsenate by Using Coal Mine Drainage Sludge in Aqueous Phase

Abstract In this research, equilibrium of adsorption and kinetics of As(V) removal were investigated. The coal mine drainage sludge(CMDS) was used as adsorbent. To find out the physical and chemical properties of CMDS, XRD (X-ray diffraction), XRF (X-ray fluorescence spectrometer) analysis were carried out. The CMDS was consist of 70% of goethite and 30% of calcite. From the results, an adsorption mechanism of As(V) with CMDS was dominated by iron oxides. Langmuir adsorption isotherm model was fitted well more than Freundlich isotherm adsorption model. Adsorption capacities of CMDS 1 was not different with CMDS 2 on aspect of amounts of arsenic adsorbed. The maximum adsorption amount of two CMDS were respectively 40.816, 39.682 mg/g. However, the kinetic of two CMDS was different. The kinetic was followed pseudo second order model than pseudo first order model. Concentrations of arsenic in all segments of the polymer in CMDS 2 does not have a constant value, but the rate was greater than the value of CMDS 1. Therefore, CMDS 2, which is containing polymer, is more effective for adsorbent to remove As(V).

Degradation Properties of Ibuprofen Using Photocatalytic Process

【In this study, Ibuprofen (IBP) degradation by the photo catalytic process was investigated under various parameters, such as UV intensity, optimum dosage of

Arsenite Oxidation by Ultrasound Combined with Ultraviolet in Aqueous Solution

TiO_2

Addition of Sonochemical Reactor to the Solar Photocatalytic Compound Parabolic Concentrators System

, alkalinity, temperature and pH of bulk solution. The pseudo-first order degradation rate constants were in the order of

Catalytic assistance of ultrasound for manganese removal by waste oyster shells

10^{-1}

3Pb4-11 酸化剤(ペルオキソ二硫酸カリウム)を用いたソノケミカル反応によるシアン化物イオンの酸化(ポスターセッション)

to

2Pb4-11 水溶液中での超音波と紫外線併用によるヒ素の酸化(ポスターセッション)

10^{-4}min^{-1}