Name: PAULO ANDRÉ PRATA DECOTÉ
Publication date: 08/07/2022
Advisor:
Name |
Role |
|---|---|
| MARIA DE FATIMA PEREIRA DOS SANTOS | Advisor * |
| MARISTELA DE ARAUJO VICENTE | Co-advisor * |
Examining board:
| Name |
Role |
|---|---|
| MARIA DE FATIMA PEREIRA DOS SANTOS | Advisor * |
| MARISTELA DE ARAUJO VICENTE | Co advisor * |
Summary: In this work, a methodology was proposed for the cátions determination (Li+, Na+, NH4+, K+, Mg2+, Ca2+, Sr2+ e Ba2+) and for the determination of short-chain organic acids (formic, acetic and propanoic acid) by ion chromatography in oil samples after extraction process following the ASTM D6470. Fifteen oil samples were used,
characterized in terms of density, API grade, Total Acid Number (TAN), salinity and water content. ASTM D6470 method was implemented modified 3-way flask for insertion of a Pt100 termoresistor for temperature control and a copper capillary for
smooth airflow. Ion chromatography was evaluated of eluent composition, matrix effect, resolution, linearity, accuracy, repeatability, intermediate precision limit of detection (LOD) and limit of quantification (LOQ). In the cations analysis in petroleum, sodium (Na+) was identified in all samples at concentrations from 0.5 to 4853 mg kg-1, calcium (Ca2+) in most samples from 2 to 880 mg kg-1, and magnesium (Mg2+) from 0.8 to 69 mg kg-1 of oil. In lower concentrations, lithium (Li+) (5 to 10 mg kg-1), ammonium (NH4+) (1 to 10 mg kg-1), potassium (K+) (0.7 to 31 mg kg-1) and strontium (Sr2+) (1 to 25 mg kg-1). In the samples studied, the concentration of barium (Ba2+) was below the limit of quantification (1.09 mg kg-1). For organic acids in petroleum, formic acid was
determined in 14 of the 15 oils studied in the range of 0.80 to 25 mg kg-1. Acetic acid was determined from 15 oil samples in the range of 2 to 560 mg kg-1. Propanoic acid was found in nine of the fifteen oils (1 to 3 mg kg-1). It was observed that the oils that presented higher concentrations of acids (above 12 mg kg-1 for formic acid and acetic
acid) also contained higher contents of water (1.03% to 7.26% m/m), which contribute the hypothesis that these acids are removed in oil dehydration processes. Therefore, using the proposed methodology, this work evidenced the possibility ion chromatography applying-in the speciation and quantification of the cations types, as
well as the short-chain organic acids present in petroleum, which can possible the study of several effects, such as corrosive processes, fouling in distillation, poisoning of catalysts and influence on the determination of physicochemical characteristics of petroleum, such as the Total Acid Number.
