PubMed · 15626142
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Daniel G Federman, Robert S Kirsner. Inglorious "old glory".. https://pubmed.ncbi.nlm.nih.gov/15626142/
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The transfer mechanism of an amphoteric rhodamine, sulforhodamine 101 (SR101), across the polarized water/1,2-dichloroethane (DCE) interface was investigated using cyclic voltammetry, differential voltfluorometry and potential-modulated fluorescence (PMF) spectroscopy. The voltammetric response for the ion transfer of SR101 monoanion from water to DCE was observed as the diffusion-controlled transfer process. An unusual voltammetric response was found at 0.15 V more negative than the formal transfer potential of SR101(-) (deltaW(O)phi degrees') in the cyclic voltammogram and voltfluorogram. The frequency dependence of the PMF responses confirmed the presence of the adsorption processes at negative potentials. In addition, a further transient adsorption step was uncovered at deltaW(O)phi degrees'. The interfacial mechanism of SR101 is discussed by comparing the results obtained from each technique.
In order to have energy and cost effective separation of dyes, a combination of advanced oxidation process (AOP) using Fenton's reagent and nanofiltration (NF) is proposed. Three combinations of AOP and NF are studied using a synthetic solution of eosin dye. Scheme-1 is AOP followed by NF. Scheme-2 is NF followed by AOP. And Scheme-3 is two-step NF. The concentration of eosin dye studied in the first step of each of the schemes is in the range of 70-200mg/l. The operating transmembrane pressures for NF steps are 552, 689 and 828kPa. The crossflow velocities are 0.46, 0.69 and 0.91m/s. The schemes are compared for permeate flux, permeate concentration and duration of operation. In Scheme-1, AOP is conducted for 30min, and then subjected to NF, whereas in Scheme-2, the time needed for AOP is more than 3h to achieve the concentration level of the dye below 1mg/l. Thus, it is found that Scheme-1 is superior to Scheme-2 due to lesser time requirement. However, Scheme-3 involving no AOP, is also suitable for dye separation as the final eosin concentration in the permeate falls below 1mg/l. Scheme-1 is found suitable for dye concentration of 70mg/l and the most appropriate composition of Fenton's reagent is 1665mg/l of H(2)O(2) and 347.5mg/l of FeSO(4)x7H(2)O. Suitable NF operating conditions in step 2 of Scheme-1 is transmembrane pressure of 689kPa and crossflow velocity of 0.91m/s. In Scheme-3, the suitable operating conditions for NF in both the steps are 828kPa transmembrane pressure and 0.91m/s crossflow velocity. Scheme-2 is found to be unsuitable.
OBJECTIVE: The aim of this study was to determine if there is a significant correlation between the in vivo presence of periapical radiolucency and ex vivo apical dye penetration on the same human teeth. STUDY DESIGN: Eighty-four endodontically filled teeth that were scheduled for extraction were classified into 2 groups according to the presence or absence of a periapical radiolucency and further divided into 2 subgroups according to the quality of the root canal filling. After extraction, the apical filling was evaluated by a dye penetration method. RESULTS: The dye extraction evaluation showed no correlation between apical dye penetration and the presence of a periapical radiolucency (not significant), but a statistically significant correlation with the quality of the root canal filling (P = .03). CONCLUSION: The results of the dye penetration study were correlated to the quality of the root canal filling but had no predictive value for the development of periapical radiolucency.