Organic acids and inorganic anions in Bayer liquors by ion chromatography after solid-phase extraction

A method for the simultaneous separation and determination of organic acids and inorganic anions in Bayer liquors was developed by gradient ion chromatography with suppressed conductivity detection. Formate, acetate, propionate, oxalate, succinate, glutarate, fluoride, chloride and sulfate were separated and determined in 33 min. The samples were pretreated with solid-phase extraction, which has high selectivity for removing a large number of metallic ions in the Bayer liquors, and filtered with a 0.45 μm filter membrane before being injected into the ion chromatographic system. The separation of six organic acids and three inorganic anions was achieved on an IonPac AS11-HC column with KOH as the eluent, and the detection was performed by a conductivity detection mode. No interference is found in the presence of fluorate, chlorate and sulphate when organic acids are determined. The calibration graphs of peak area for all the analytes are linear over a wide range. The relative standard derivation of the peak area of analytes is less than 2.14%. Under optimum conditions the detection ranges from 0.2 to 100.0 mg/L. The average recoveries of the added standards are between 94.3% and 102.8%.

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water. Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time. Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfactory linear range, limits of detection and good repeatability were obtained. The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.

Fe-based metallic glass as heterogeneous Fenton-like catalyst for azo dyes degradation:effect of inorganic anions

Metallic glasses(MGs) are promising heterogeneous catalysts in water remediation,due to their superior efficiency,selectivity,reusability and corrosion resistance.However,few works are focused on the influence of inorganic anions that are abundant in wastewater.Herein,four common inorganic anions were added in a heterogeneous Fenton-like system(Fe-MG/H_(2)O_(2)) to study inorganic anions' influence on MGs' catalytic performance during methylene blue(MB) degradation.Evidence demonstrated that chloride ions and dihydrogen phosphate ions had an adverse effect on the catalytic performance of Fe-MG,whereas Fe-MG/H_(2)O_(2) system sustained high efficiency in the presence of sulfate ions and nitrate ions during the Fenton-like process.By studying the structure,surface morphology,and evolution of active species,it was found that inorganic anions had a significant effect on the surface morphology of Fe-MG and the generation of active species.This work will provide essential references for MGs as heterogeneous catalysts in practical applications.

Research on Inorganic Anion Recognition of Calix[4]pyrroles and Dipyrrylmethanes by Capillary Zone Electrophoresis

Capillary electrophoresis （CE） can separate charged and neutral substances with high speed and efficiency. In this paper, utilizing meso-octamethylcalix[4]pyrrole, meso-tetraspirocyclohexylcalJx[4]pyrrole, bimethyl bi（2-pyrryl）- methane and 1,1-bi（2-pyrryl）cyclohexane as additives in capillary zone electrophoresis （CZE） electrolyte, their recognition ability to inorganic anions was discussed. The dipyrrylmethanes have better recognition ability than others. Their effects on separation of seven normal inorganic anions by CZE were studied.

Sonocatalytic activity of LuFeO_3 crystallites synthesized via a hydrothermal route

LuFeO3 crystallites of different sizes and morphologies were synthesized via a hydrothermal route. The sonocatalytic properties of the as-synthesized samples were investigated by degrading various organic dyes, including acid orange 7 （AOT）, rhodamine B （RhB）, methyl orange （MO）, and methylene blue （MB）, under ultrasonic irradiation, revealing that they exhibit excellent sonocatalytic activity toward the degradation of these dyes. Particularly, the synthesized bar-like particles with lengths of-3 μm and widths of-1μm have the highest sonocatalytic activity, and the degradation percentage of AO7 reaches 89% after 30 min of sonocatalysis. The effects of inorganic anions such as CI-, NO3-, SO42-, PO43-, and HCO3- on the sonocatalysis efficiency were investigated. Hydroxyl radicals （·OH） detected by fiuorimetry using terephthalic acid as a probe molecule were found to be produced over the ultrasonic-irradiated LuFeO3 particles. The addition of ethanol, which acts as a· OH scavenger, leads to quenching of ＂OH radicals and a simultaneous decrease in the dye degrada- tion. This suggests that ＂OH is the dominant active species responsible for the dye degradation.

Selection of magnetic anion exchange resins for the removal of dissolved organic and inorganic matters

Four magnetic anion exchange resins （MAERs） were used as adsorbents to purify drinking water. The effect of water quality （pH, temperature, ionic strength, etc.） on the performance of MAER for the removal of dissolved organic matter （DOM） was also investigated. Among the four studied MAERs, the strong base resin named NDMP- 1 with high water content and enhanced exchange capacity exhibited the highest removal rate of dissolved organic carbon （DOC） （48.9% removal rate） and UV-absorbing substances （82.4% removal rate） with a resin dose of 10 mL/L after 30 rain of contact time. The MAERs could also effectively remove inorganic matter such as sulfate, nitrate and fluoride. Because of the higher specific UV absorbance （SUVA） value, the DOM in the raw water was found to be removed more effectively than that in the clarified water by NDMP resin. The temperature showed a weak influence on the removal of DOC from 6 to 26℃, while a relatively strong one at 36℃. The removal of DOM by NDMP was also affected to some extent by the pH value. Moreover, increasing the sulfate concentration in the raw water could decrease the removal rates of DOC and UV-absorbing substances.