Binary coalescence of water drops in organic liquids has several commercial applications that are related to the stabilization of emulsions. The stability of the emulsion is dependent on adsorption of the surfactant molecules at the water/organic interface. In this work, the adsorption of ionic surfactants at water/organic interfaces, both in the presence and absence of salt, and its effect on binary coalescence were studied. The ionic surfactants used were sodium dodecyl sulfate and cetrimide. The organic phase was constituted from either toluene or carbon tetrachloride. Adsorption was studied by measuring the interfacial tension. The presence of salt had a strong effect on the interfacial tension in the presence of these surfactants. In the absence of surfactant, salt had little effect on interfacial tension. The data were fitted using a surface equation of state that was developed from the Gibbs adsorption equation and the Langmuir isotherm. Binary coalescence of water drops in toluene was studied in a specially designed coalescence apparatus. Coalescence time did not have a single value but a stochastic distribution of coalescence time was observed in each case. The addition of salt had a significant effect on coalescence time. A stochastic model was used to characterize the distributions.
Due to the harmful effects of heavy metal ions such as lead, chromium, and others, an economic and eco-friendly removal process using green adsorbent is required to make water bodies safe. Rice husk is used as an adsorbent in continuous column mode for the removal of Pb(II) and Cr(VI) ions. The variations of column process parameters like influent metal concentration, bed height, the rate of flow, etc., are investigated to study the breakthrough behavior. The higher bed height but lower flow rate and influent concentration give the better result. The experimental data fitted well to that of the empirical models. The Thomas model and Yoon-Nelson model fit the experimental data well. GA-ANN-based hybrid network has been used for modeling purpose.
The study presents the removal of Cu(II) ions using bio‐adsorbents. The applicability of the continuous column process using hyacinth root, rice husk, blackberry leaves, and guava leaves is reported in this study. The effects of solution pH were studied in batch mode, and other different process parameters such as bed depth, rate of flow, influent solution concentration were investigated and optimized in the continuous mode. The breakthrough curves were obtained for various initial metal concentrations (10, 20, and 30 mg.L−1), flow rates (10, 30, and 40 ml.min−1), and bed height (4, 6, and 10 cm). The optimum operating conditions were 10 cm bed depth, 10 ml.min−1 flow rate, 10 mg.L−1 influent concentration, and pH 6. The breakthrough time was increased with increasing bed height and decreasing flow rate and influent concentration. The Freundlich isotherm model was in good agreement (R2 = .9247–.9987) with the batch experimental data whereas, the continuous experimental data fitted well in the Thomas model to illustrate the best performance of the fixed‐bed process. FTIR spectra and SEM images verify the sorption capacity of the adsorbents. The Cu(II) adsorption capacities of the adsorbents were compared, and the hyacinth root gives the best result compare to the others. Hence, the results proved the effectiveness of the adsorbents for the removal of Cu(II) ions.
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