Studies on CMC and thermodynamic function of anionic surfactants in DMA/long-chain alcohol systems using microcalorimetric method |
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Authors: | Honglin Zhang Zhe Kong Yongmei Yan Ganzuo Li Li Yu Zhen Li |
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Institution: | (1) College of Chemical Science, Qufu Normal University, Qufu, 273165, China;(2) Key Lab for Colloid and Interface Chemistry of Ministry of Education, Shandong University, Jinan, 250100, China |
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Abstract: | The critical micelle concentration (CMC) and the thermodynamic function of the anionic surfactant, sodium laurate (SLA) and
sodium dodecyl sulfate (SDS) in the N,N-dimethyl acetamide (DMA)/long-chain alcohol systems were studied using titration microcalorimetric method. The power-time
curves of SLA and SDS in the presence of a long-chain alcohol (n-heptanol, n-octanol, n-nonanol, n-decanol) in the DMA medium were determined. Then, from the curves, the critical micelle concentration (CMC) and the thermodynamic
standard formation functions (ΔH
ϑ
m, ΔG
ϑ
m and ΔS
ϑ
m) were obtained through thermodynamic theories. The relationships between temperature, alcohol’s carbon number, concentration
and thermodynamic properties were discussed. For SLA or SDS in a DMA solution, under the same concentration of alcohol, the
values of CMC, ΔH
ϑ
m and ΔS
ϑ
m increase, while the value of ΔG
ϑ
m decrease with the increase of temperature. Under the same condition of identical temperature and alcohol concentration, the
values of CMC, ΔH
ϑ
m, ΔG
ϑ
m and ΔS
ϑ
m decrease with the increase of the alcohol’s carbon number. In the presence of the same kind of alcohol, the values of CMC
and ΔG
ϑ
m increase, but the values of ΔH
ϑ
m and ΔS
ϑ
m decrease with the concentration increases in alcohol series at the same temperature.
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Translated from Acta Chimica Sinica, 2007, 65(10): 906–912 译自: 化学学报] |
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Keywords: | microcalorimetric method N N-dimethyl acetamide sodium laurate sodium dodecyl sulphate long-chain alcohol critical micelle concentrations (CMC) thermodynamic function |
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