The application of polycarboxylic acid as a fluid loss additive for cement(i.e.,a substance specifically designed to lower the volume of filtrate that passes through the cement)can prolong the thickening time of cemen...The application of polycarboxylic acid as a fluid loss additive for cement(i.e.,a substance specifically designed to lower the volume of filtrate that passes through the cement)can prolong the thickening time of cement slurries.Given the lack of data about the effects of carboxylic acid monomers as possible components for the additives traditionally used for oil-well cement,in this study different cases are experimentally investigated considering different types of these substances,concentrations,temperatures,and magnesium ion contamination.The results demonstrate that itaconic acid has a strong retarding side effect,while maleic and acrylic acids have similar influences on the thickening time of the cement slurry.The rheological properties of the cement slurry tend to deteriorate when the carboxylic acid monomer content in the fluid loss additive is increased to 40%.If the temperature exceeds 80°C,there is a significant decrease in the related impact on the thickening duration.With an increase in the intrusion of magnesium ions to>0.5%,both the rheological properties of the cement slurry and the thickening time are affected in a negative way.展开更多
The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid. The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been stu...The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid. The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied. The presence of the species of tartaric acid in Polyacrylonitrile produced by using ceric ion/tartaric acid as niitiator has been confirmed by FT-IR analysis.展开更多
A study was conducted to find out the effect of citric acid on total monomeric anthocyanins and antioxidant activity of liquor made from unprocessed purple-leafed TRFK 306 Kenyan tea, brewed at various time/temperatur...A study was conducted to find out the effect of citric acid on total monomeric anthocyanins and antioxidant activity of liquor made from unprocessed purple-leafed TRFK 306 Kenyan tea, brewed at various time/temperature combinations. Most purple tea consumers usually brew the tea leaves then add some lemon juice before consuming it. Citric acid was used here to mimic the use of lemon juice. Documentation on the quality of such a brew is scanty and the effect of acid on its quality is equally scanty. The current study used brewing time/temperature combinations of 5, 10 and 15 minutes with 70°C and 92°C drinking water. Total monomeric anthocyanins were analysed using UV-1800 spectrophotometer (Shimadzu, Japan) while DDPH method was used to assay for antioxidant activity. Citric acid concentration of 0, 0.1% to 0.5% was used to check their effect on the brews with the highest total anthocyanins and antioxidant activity. The results showed that brewing temperature of 70°C had 9.5 mg/L to 27.7 mg/L, with 5 minutes brewing time being the highest. Temperature of 92°C had 37.5 mg/L to 92 mg/L with 5 minutes brewing time having the highest total monomeric anthocyanins. Antioxidant activity of 92°C brewing temperature ranged from 90.7% to 92.0%. Total monomeric anthocyanins increased with increased citric acid concentration up to 0.3% before it decreases while for antioxidant activity, it decreased with addition of citric acid. It was concluded that for maximum anthocyanins extraction, 5 minutes brewing time is the best while ten minutes brewing time could give optimum antioxidant activity.展开更多
文摘The application of polycarboxylic acid as a fluid loss additive for cement(i.e.,a substance specifically designed to lower the volume of filtrate that passes through the cement)can prolong the thickening time of cement slurries.Given the lack of data about the effects of carboxylic acid monomers as possible components for the additives traditionally used for oil-well cement,in this study different cases are experimentally investigated considering different types of these substances,concentrations,temperatures,and magnesium ion contamination.The results demonstrate that itaconic acid has a strong retarding side effect,while maleic and acrylic acids have similar influences on the thickening time of the cement slurry.The rheological properties of the cement slurry tend to deteriorate when the carboxylic acid monomer content in the fluid loss additive is increased to 40%.If the temperature exceeds 80°C,there is a significant decrease in the related impact on the thickening duration.With an increase in the intrusion of magnesium ions to>0.5%,both the rheological properties of the cement slurry and the thickening time are affected in a negative way.
文摘The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid. The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied. The presence of the species of tartaric acid in Polyacrylonitrile produced by using ceric ion/tartaric acid as niitiator has been confirmed by FT-IR analysis.
文摘A study was conducted to find out the effect of citric acid on total monomeric anthocyanins and antioxidant activity of liquor made from unprocessed purple-leafed TRFK 306 Kenyan tea, brewed at various time/temperature combinations. Most purple tea consumers usually brew the tea leaves then add some lemon juice before consuming it. Citric acid was used here to mimic the use of lemon juice. Documentation on the quality of such a brew is scanty and the effect of acid on its quality is equally scanty. The current study used brewing time/temperature combinations of 5, 10 and 15 minutes with 70°C and 92°C drinking water. Total monomeric anthocyanins were analysed using UV-1800 spectrophotometer (Shimadzu, Japan) while DDPH method was used to assay for antioxidant activity. Citric acid concentration of 0, 0.1% to 0.5% was used to check their effect on the brews with the highest total anthocyanins and antioxidant activity. The results showed that brewing temperature of 70°C had 9.5 mg/L to 27.7 mg/L, with 5 minutes brewing time being the highest. Temperature of 92°C had 37.5 mg/L to 92 mg/L with 5 minutes brewing time having the highest total monomeric anthocyanins. Antioxidant activity of 92°C brewing temperature ranged from 90.7% to 92.0%. Total monomeric anthocyanins increased with increased citric acid concentration up to 0.3% before it decreases while for antioxidant activity, it decreased with addition of citric acid. It was concluded that for maximum anthocyanins extraction, 5 minutes brewing time is the best while ten minutes brewing time could give optimum antioxidant activity.
