Turbulence-assisted high throughput liquid-liquid extraction in microfluidics and Ni(OH)2 nanoparticles for electrochemical determination of glycol traces in natural gas condensate
Gabriela F. Giordano†,‡ Camila L. de Camargo, †,€ Luis C. S. Vieira,† Marcos A. d’Ávila,€ Bruno C. Couto,£ Rogério M. Carvalho,£ Angelo L. Gobbi,† and Renato S. Lima†,‡,*
† Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP 13083-970, Brasil.
£ Centro de Pesquisas e Desenvolvimento Leopoldo Américo Miguez de Mello, Petrobras, Rio de Janeiro, RJ 21941-598, Brasil.
‡ Instituto de Química, Universidade Estadual de Campinas, Campinas, SP 13083-970, Brasil.
€ Faculdade de Engenharia Mecânica, Universidade Estadual de Campinas, Campinas, SP 13083-860, Brasil.
ABSTRACT: While monoethylene glycol (MEG) is an efficient alternative to prevent the generation of hydrates into the natural gas (NG) processing pipes, this specie also generates undesirable effects such as pipe corrosion, catalyst poisoning, quality loss of the fuel, and environment contamination. Thus, MEG is removed from the system in final stages of the NG processing and regenerated for reuse making mandatory its monitoring in both regenerated samples and fuels like the NG condensate (NGC). We address herein a simple and fast method to determine MEG traces in NGC which was based on two stages, microfluidic liquid-liquid extraction (LLE) and electrochemical detection. High throughput (residence time of 0.05 s) and efficient LLEs were obtained in a single run by pumping the immiscible phases at harsh flow rates (up to 40 mL min−1) into a bulky chip (without interface) composed of bisphenol A-based epoxy resin, which was prototyped using a cleanroom-free and bondless approach. This unprecedented substrate in microfluidics showed resistance to elastic deformation and swelling in different organic media. The extraction was essential to allow the electrochemical determination of MEG, in which the aqueous acceptor phase from LLE was used as electrolytic sample. Nickel disk modified with Ni(OH)2 nanoparticles provided a sensitive quantification of MEG due to the high electrode surface area and catalytic activity of Ni(OH)2 for irreversible oxidation of MEG. This electrode further requires a simple surface modification. We believe the method reported in this manuscript is a powerful alternative to monitor MEG in NGC samples by the industry.
This article was published in Energy & Fuels (ACS, DOI: 10.1021/acs.energyfuels.8b00725). Such project has been conducted in Laboratório de Microfabricação (LMF, LNNano).