Zheng Jiashen

Corrosion inhibition mechanism of carbon steel by sodium N,N‐diethyl dithiocarbamate in hydrochloric acid solution

The effect of sodium N,N‐diethyl dithiocarbamate (SDEDTC) on the corrosion of carbon steel in 0.5mol/L hydrochloric acid (HCl) solution was studied using weight loss, potentiodynamic polarisation curves and impedance measurement methods. Experimental results revealed that SDEDTC acted as an inhibitor in acid environments. Moreover, the compound was a mixed‐type inhibitor, acting predominantly as a cathodic inhibitor. Inhibition efficiency increased with increasing SDEDTC concentration at different temperatures. The corrosion inhibition mechanism of SDEDTC for carbon steel in HCl solution was also investigated by impedance techniques.

Inhibition of the corrosion of carbon steel in hydrochloric acid solution by bisquaternary ammonium salt

The effectiveness of bisquaternary ammonium salt N,N′‐Bis(dodecyldimethyl)‐3‐oxa‐1,5‐ pentanediammonium dichloride used as corrosion inhibitor for carbon steel in 1.0 M HCl was investigated by weight loss and electrochemical techniques. Surfaces were characterised by scanning electron microscopy. The performance of the bisquaternary ammonium salt was also compared with that of urotropine, a commercial corrosion inhibitor for acid media in industry practice. The results showed good inhibiting action of the inhibitor. The inhibition efficiency increases with the inhibitor concentration but is temperature–independent. N,N′‐Bis(dodecyldimethyl)‐3‐oxa‐1,5‐pentanediammonium dichloride acts mainly as a mixed‐type inhibitor. The inhibition of this bisquaternary ammonium compound was assumed to occur via adsorption of the inhibitor molecule on the metal surface without affecting the corrosion mechanisms. The adsorption of the inhibitor on the metal surface in HCl solution was found to obey Frumkins isotherm.

Technical note a study on the mixing characteristics of a packed flotation column

Abstract Based on the study of the flotation of phosphate, a packed column was designed for flotation of low grade phosphate and was expected to have high P2O5 recovery. Both the axially-dispersed plug flow model and the tanks in series model have been tested to simulate the flow pattern in the column. Comparison of model prediction and experimental data showed that the tanks in series model is better than the axially-dispersed plug flow model to describe the flow pattern in the collection region of the column. Simultaneously, experimental work has also described the cleaning process through adding wash water in the froth region of the column. Flotation experiments have been conducted, and high recovery is obtained as expected.

The corrosion behavior of 70/30 copper-zinc alloy under the biofilm of sulfate-reducing bacteria

A laboratory study was carried out on the effect of the biofilm of sulfate-reducing bacteria (SRB), which plays an important role in corrosion of 70/30 copper-zinc alloy in culture media under anaerobic condition. The API medium was used to culture the SRB in Zhongyuan oilfield. Potential/time measurement showed that the presence of SRB makes the corrosion potential more active with SRB growth metabolite. Electrochemical impedance spectroscopy (EIS) was used to analyse the electrode process of 70/30 Cu-Zn alloy with SRB biofilm. Scanning electron microscopy (SEM) examinations revealed the formation of biofilm and corrosion products during exposure to SRB-containing culture medium. X-ray diffraction and EDS were used to analyse the corrosion products. The results show that the variation of activity of the SRB biofilm changes with SRB growth by the linear polarization resistance (Rp) and the EIS in culture medium inoculated SRB. Korrosionsverhalten einer 70/30 Kupfer-Zink-Legierung unter dem Biofilm sulfatreduzierender Bakterien Eine Laborstudie wurde zum Einfluss des Biofilms sulfatreduzierender Bakterien (SRB) durchgefuhrt, die bei der Korrosion der 70/30 Kupfer-Zink-Legierung in Kulturmedien unter anaeroben Bedingungen eine grose Rolle spielen. Das API Medium wurde verwendet, um die SRB im Zhongyuan Olfeld zu zuchten. Potential-Zeit-Messungen zeigten, dass die Anwesenheit von SRB das Korrosionspotential durch das Wachstum von SRB-Stoffwechselprodukten aktiver machte. Um den Elektrodenprozess der 70/30 Cu-Zn-Legierung mit SRB-Biofilm zu analysieren, wurde die elektrochemische Impedanzspektroskopie (EIS) eingesetzt. Rasterelektronenmikroskopische Untersuchungen zeigten die Bildung von Biofilm und Korrosionsprodukten wahrend der Auslagerung in SRB-enthaltenem Kulturmedium. Rontgenbeugung und EDS wurden eingesetzt, um die Korrosionsprodukte zu analysieren. Die Ergebnisse bezuglich linearem Polarisationswiderstand (Rp) und EIS in mit SRB geimpftem Kulturmedium zeigten, dass die Aktivitat des SRB-Biofilms sich mit dem Wachstum der SRB andert.

The inhibition effects of a new heterocyclic bisquaternary ammonium salt in simulated oilfield water

A kind of novel heterocyclic bisquaternary ammonium salt (MBQA) was successfully synthesised with metronidazole as matrix and dichloroethyl ether as the link agent. Weight loss measurement, potentiodynamic polarisation curves, electrochemical impedance spectroscopy and atomic force microscopy were used to evaluate the corrosion inhibiting performance of MBQA in simulated oilfield water. Experimental data revealed that MBQA acted as an inhibitor in the acidic environment and, furthermore, the compound was a mixed‐type inhibitor. It was found that inhibition efficiency increased with an increase in MBQA concentration at different temperatures. The process of inhibition was attributed to the formation of an adsorbed film on the metal surface, which protected the metal against corrosive agents.