Correction to 'Organic matter removal from mother liquor of gas field wastewater by electro-Fenton process with the addition of H2O2: effect of initial pH'.

[This corrects the article DOI: 10.1098/rsos.191304.].

Organic matter removal from mother liquor of gas field wastewater by electro-Fenton process with the addition of H2O2: effect of initial pH.

The electro-Fenton (EF) process was applied to treat mother liquor of gas field wastewater (ML-GFW). The Fe-Fe electrodes were used and H2O2 was added to the EF system. Effect of initial pH on chemical oxygen demand (COD) removal efficiency, specific electrical energy consumption (SEEC), specific electrode plate consumption (SEPC) and organic matter removal mechanism was investigated. The results showed that COD removal efficiency reached the maximum (71.9%) at initial pH of 3 after reaction for 3 h. Besides, considering with the SEEC and SEPC, pH of 3 was also the best choice, at which SEEC was 4.7 kW h kgCOD -1, SEPC was 0.82 kgFe kgCOD -1. Organic matter removal was achieved by two ways: oxidation and flocculation, and oxidation played a major role. With the analysis of GC-MS, the possible degradation pathways of the representative contaminants in the ML-GFW were given.

[Analysis of XPS in the Removal of Cr(â ¥) from Groundwater with rGO-nZâ ¥].

Iron nanoparticles are widely used in heavy metal ions removal from water, but because of the characteristics of easily aggregation and transference in the groundwater, remediation effect was reduced. GO with a negative charge containing oxygen-containing functional groups on the surfaces of graphene, are widely used for the removal of heavy metal ions from water, but it has little on remediating hexavalent chromium (Cr2O2-7, CrO2-4) with negatively charged electrons. Therefore, rGO-nZⅥ was synthesized via liquid phase reduction method to overcome the aggregation and transference of FeO, changing the negative charged Cr2O2-7 or CrO2-4 to positive charged Cr3+. The material behavior characteristics of Cr(Ⅵ) removal were discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to test the prepared rGO-nZⅥ. Results indicated that nZⅥ was successfully loaded on the surface of GO, and the shape of the particles was approximate ball and the granular diameter ranged from 20 to 100 nm. Removal efficiency of Cr(Ⅵ) (40 mg·L-1) from water was nearly 100% within 24 h using rGO-nZⅥ. X-ray photoelectron spectroscopy (XPS) analyses using the XPSPEAK41 program indicated that FeO firstly reduced negatively charged Cr(Ⅵ) to positively charged Cr(Ⅲ) by providing electron, then the chromium in the solution can be removed as chromium hydroxide (Cr(OH)3) by a hydrolysis precipitation process. As the reaction progress, materials charges were changing, which benefited adsorpting Cr(Ⅵ). After 24 h reaction, the residual nZⅥ loading on rGO-nZⅥ remained, which showed the potential of sequentially remediating contamination. The results showed important theoretical value and practicability.

[Secreted expression of porcine interferon-gamma gene in Pichia pastoris].

The porcine interferon-gamma (PoIFN-gamma) gene, in which the sequence encoding signal peptide was replaced by that of the alpha-factor of Saccharomyces cerevisiae, was cloned into Pichia pastoris expression vector pPIC9K. The recombinant plasmid pPIC9K-alpha-PoIFN-gamma was then transformed into Pichia pastoris GS115 cells by electroporation and stable multicopy recombinant Pichia pastoris strains were selected by G418 resistance. Two recombinants of multiple inserts were obtained. SDS-PAGE and Western blot assays of culture broth from a methanol-induced expression strain demonstrated that recombinant PoIFN-gamma, 17kD and 23kD proteins, were secreted into the culture medium. Target proteins, 60% of total proteins, were obtained in the culture medium at the concentration of 108 mg/L. This is the first secreted expression of porcine interferon-gamma gene in Pichia pastoris.