Cao Shun-an

Direct determination of bromide ions in sea water by ion chromatography using water as the mobile phase

Abstract A rapid and simple ion chromatographic (IC) method for the direct determination of bromide (Br − ) in sea water was developed. A small amount of sea water was injected into a specific IC system where zwitterionic surfactants immobilized on octadecylsilica (ODS) surfaces were used as the stationary phase and water was used as the mobile phase. The matrix ions, SO 2− 4 , Cl − , Na + , K + , Mg 2+ and Ca 2+ were initially eluted as ion pairs of Na + K + - SO 2− 4 , Na + K + -2 Cl − and Mg 2+ Ca 2+ -4 Cl − before the ion pair Mg 2+ Ca 2+ -4 Br − which contained the target ion (Br − ). The retention interval between Mg 2+ Ca 2+ -4 Br − and Mg 2+ Ca 2+ -4 Cl − (the last eluted matrix ion pair) was long enough for the base-line separation of Br − . Bromide ions in sea water could be determined within 4.3 min by using this IC system (a zwitterionic column, 4.6 × 250 mm; a water mobile phase, 1.0 ml/min; and 20 μl of sample injection).

On-line monitoring of trace amounts of copper(II) in steam condensate and boiler feed-water by flow injection analysis based on its catalytic effect on the oxidation of hydroquinone by hydrogen peroxide

A flow injection analysis (FIA) method for on-line monitoring of trace amounts of copper(II) in steam condensate and boiler feed-water is described. This method is based on the catalytic effect of copper(II) on the oxidation of hydroquinone by hydrogen peroxide, the quinone produced being detected using UV-absorption at 490 nm. The effects of pH, temperature, the concentrations of hydroquinone and hydrogen peroxide, and reaction time on the determination of the selectivity and the sensitivity of this method were investigated. An FIA-kinetic determination method with both high selectivity and sensitivity was obtained by the optimization of the detection conditions. Trace amounts of copper(II) in steam condensate and boiler feed-water in power stations were successfully analyzed on-line using this method.

The effect of sulfide on the corrosion behavior of carbon steel in natural waters

Purpose – To study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions.Design/methodology/approach – The mass‐loss method, electrochemical tests and surface analysis were used to study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions.Findings – General corrosion occurred when No. 20 carbon steel was immersed in both test solutions (concentrated sample with S2− added to 0.8 mg/L, and pure concentrated sample with no S2− added). The presence of S2− in test solutions accelerated the corrosion rate of No. 20 carbon steel.Practical implications – In order to prevent No. 20 carbon steel in water with S2− from corroding, S2− must be removed.Originality/value – It was found that the presence of S2− in test solutions accelerated the corrosion rate of No. 20 carbon steel in this paper. Therefore, when water containing sulfide ions is used as the source of make‐up water and...

A quantum chemistry calculation study on the inhibition efficiency of the para‐chlorobenzene nitriles on carbon steel in hydrochloric acid

The inhibition mechanism and the relationship between the inhibition efficiency of para‐chlorobenzene nitriles on carbon steel in hydrochloric acid, and their molecular structure, were studied by microscopy and quantum chemistry calculations. The inhibition of carbon steel was achieved by chemisorption of the para‐chlorobenzene nitriles onto the surface of the carbon steel. The greater was the σN (absolute value) and the less the ELUMO value, the greater was the inhibition efficiency.

A study of the influence of chloride ion concentration on the corrosion behavior of carbon steel in phosphate high‐temperature boiler water chemistries

Purpose – This paper sets out to study the corrosion of No. 20 carbon steel without film and with films of different qualities in high‐temperature boiler water with different Cl− concentrations.Design/methodology/approach – The static simulated experiment in high‐pressure autoclave and the surface analysis methods of EPMA and XRD were carried out to study the corrosion effect.Findings – Under the following conditions: T=360±3°C, pH = 9.40±0.10, cO2  0.2 mg/l. The film on specimens with integral films would not dissolve observably even until the CCl− concentration was as high as 0.8 mg/l. Films with corrosion pits would begin dissolving when the Cl− concentration reached 0.4 mg/l. The main constituents of the oxidative films in the gas and liquid phases both were Fe3O4.Practical implications – In order to prevent carbon steel from corroding in boiler water contain...

Effects of passivator on lifetime and electrical properties of insulating paper

This paper conducted thermal aging experiments under 120°C to study the effects of passivator on insulating paper (board). Experiment group (oil containing passivator and typical materials inside transformer) and control group (oil containing typical materials inside transformer but no passivator) were prepared for thermal aging experiments, and the degree of polymerization of insulating paper, furfural products in oil and the breakdown voltage, insulation resistance and dielectric dissipation factor of insulating board were tested, respectively. The results show that the furfural content in oil, the degree of polymerization of insulating paper and the breakdown voltage, insulation resistance and dielectric dissipation factor of insulating board of the experiment group were very similar to that of the control group under the same aging conditions, and passivator did not bring damage to the insulating paper (board).

Corrosion control of rusted carbon steel using hexametaphosphate and zinc sulfate in RO product water

Purpose – The purpose of this investigation was to study the effects of sodium hexametaphosphate and zinc sulfate on the corrosion control of rusted iron in reverse osmosis (RO) product water of seawater. Design/methodology/approach – The synergistic effects and inhibition effects of corrosion inhibitors on rusted carbon steel were studied using the weight-loss method, electrochemical tests and surface analysis techniques. Findings – The results indicated that sodium hexametaphosphate could partly suppress the corrosion of rusted steel, but zinc sulfate used alone had no inhibition effect. Hexametaphosphate and zinc sulfate showed a strong synergistic effect and the optimal ratio of two chemicals was 1:1. The inhibition efficiency appeared to increase with increasing inhibitor concentration and the ideal dosage of inhibitors was set at 20 mg/L, when chemical cost and inhibition efficiency were taken into account. Surface analysis results proved that this compound inhibitor could make the rust layer much m...