Novel Sample Pretreatment to Determine Iron Counts in Sour Glycol Streams by Spectrophotometer

2021 ◽  
Author(s):  
Mohamed Mahmoud ◽  
Ahmed Alsalman ◽  
Hassan Almalki
Keyword(s):  
Inductively Coupled Plasma ◽  
Oil And Gas ◽  
Iron Concentration ◽  
Sample Pretreatment ◽  
Standard Addition ◽  
Test Method ◽  
Icp Oes ◽  
Important Indicator ◽  
Main Challenge ◽  
Amine Additives

Abstract Determination of Iron Content in Triethylene glycol (TEG) samples is a very important indicator in measuring the system corrosion rate in oil and gas facilities. This study employed the application of an alternative/easy and reliable test method, which involved the use of a spectrophotometer for quantification of Iron concentration in tri ethylene glycol samples, that are used in sour gas dehydration units, rather than the sophisticated technique of Inductively Coupled Plasma Optical Emission Spectroscopy, ICP-OES. The main challenge was how to eliminate/minimize the significant interference from the carryover condensate hydrocarbons, BTEX, H2S and amine additives, which cause either precipitation with spectrophotometer reagents or turbid samples. The sample pretreatment process included: 1 - Sample digestion with dilution to eliminate the dissolved acid gases and the dissolved BTEX from the sample in acidic medium; 2 - pH adjustment from 9 – 10.5 to eliminate the amine additives interference with spectrophotometer reagents and 3 – Application of standard addition technique with certified reference material for iron with dilution, to reach the spectrophotometer detection limit and give intense color with more UV absorbance. The method was validated against ICP-OES and the results variance were within 10% acceptance criteria.

Continuing Assessment of the 5-Day Sodium Carbonate-Ammonium Nitrate Extraction Assay as an Indicator Test for Silicon Fertilizers

2015 ◽  
Vol 98 (4) ◽  
pp. 890-895 ◽  
Author(s):  
Wendy Zellner ◽  
Russell L Friedrich ◽  
Sujin Kim ◽  
Douglas Sturtz ◽  
Jonathan Frantz ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Sodium Carbonate ◽  
Inductively Coupled Plasma ◽  
Colorimetric Assay ◽  
Optical Emission ◽  
Test Method ◽  
Icp Oes ◽  
Molybdenum Blue ◽  
Inductively Coupled ◽  
Bof Slag

Abstract The 5-day sodium carbonate-ammonium nitrate extraction assay (5-day method) has been recognized by the American Association of Plant Food Control Officials as a validated test method to identify fertilizers or beneficial substances that provide plant-available silicon (Si). The test method used the molybdenum blue colorimetric assay to quantify percentage Si; however, laboratories may use inductively coupled plasma optical emission spectroscopy (ICP-OES) for elemental analysis. To examine the use of either colorimetric or ICP-OES methods for Si determination, the 5-day method was performed on the following Si-containing compounds; wollastonite, sand, biochar, and a basic oven furnace (BOF) slag. Grow-out studies using Zinnia elegans were also performed using varying rates of the wollastonite, biochar, and BOF slag. Our results show using the 5-day method, wollastonite had the highest extracted amounts of silicic acid (H4SiO4) at 4% followed by biochar (2%), BOF slag (1%), and sand (0%). Extraction values calculated using either the molybdenum blue colorimetric assay or ICP-OES for detection of the H4SiO4 had a significant correlation, supporting the application of either detection method for this type of analysis. However, when extracted values were compared to amounts of Si taken up by the plants, the 5-day method overestimated both wollastonite and biochar. While this method is a valid indicator test for determining a soluble Si source, other plant species and methods should be perused to potentially provide more quantitative analyses for plant-available Si content of all materials.

Sign in / Sign up

Export Citation Format

Share Document