The Ph Dependent Thermal Stability of the Organic Tracers 1,5-NDS and 2-NSA

Abstract

The pH dependence of the thermal stability of 1,5-naphthalene disulfonate and 2-naphthalene sulfonate have been investigated. The experiments were conducted using batch autoclave reactors. Two experimental temperatures were investigated (200?, 300?). The pH ranged from 3 to 9.85 and two ionic strengths were used (0.001 M, 0.05 M). The duration of each experiment was 40 hours.
The results show that:
1) 1,5-NDS is not stable at 300°C, pH 3, 4, 9 and 9.85, I = 0.001M, 0.05M;
2) 1,5-NDS is stable at 200°C, pH 4, I=0.001 M;
3) the low thermal stability of 1,5-NDS can be explained by two mechanisms: steric hindrance and kinetics;
4) 2-NSA is stable at 200°C pH 3, 4, 9 and 9.85, I = 0.001M, 0.05M;
5) the stability of 2-NSA at 300°C is independent of ionic strength;
6) 2-NSA is thermally stable at 300°C and pH 9.85, I = 0.05 M;
Further experiments are underway to confirm and expand our knowledge