Effect of Organized Assemblies. Part 4. Formulation of Highly Concentrated Coal−Water Slurry Using a Natural Surfactant

Abstract

Coal-water slurry has received considerable research nowadays due to its ability in substituting energy sources. The present work reports the formulation of highly concentrated coal-water slurry using a natural occurring surface active compound, saponin, extracted from the fruits of plant Sapindous laurifolia. The isolation of saponin from the plant and its surface activity has been discussed. The rhelogical characteristics of coal-water slurry have been investigated as a function of coal loading, ash content of coal, pH, temperature, and amount of saponin. The viscosity of the slurry and zeta potential are substantially decreased with concomitant shift of the isoelectric point of coal on adsorption of saponin to it. In the presence of 0.8% of saponin, coal-water slurry containing 64% weight fraction of coal could be achieved. The slurry is stable for a period of as long as 1 month in contrast to 4-5 h in the case of bare coal-water slurry. The results confirm the use of saponin as a suitable additive for coal-water slurry similar to the commercially available additive such as sodium dodecyl sulfate. Basing on the effect of pH on the zeta potential and viscosity of slurry, a suitable mechanism for saponin-coal interaction and orientation of saponin at the coal-water interface has been proposed.

Organization of amphiphiles. Part XI: Physico-chemical aspects of mixed micellization involving normal conventional surfactant and a non-ionic gemini surfactant

“…TritonX-100 even though a non-ionic one, shows a negative potential possibly due to the large number of oxygen atoms of the oxyethylene groups. Literature survey also reveals the similarities of the microenvironment of anionic surfactants and polyoxyethylated non-ionic surfactants [29,[64][65][66]. While probing the micelles of a series of polyoxyethylated non-ionic surfactants [64] and anionic surfactant SDS through the measurements of pK of a number of aldimines we have observed the similarities in the environment provided by these two categories of surfactants.…”

“…The absence of minimum in the surface tension-concentration curve of all the surfactants confirmed the high purity [>99%] of these surfactants [26][27][28]. CPC (hexadecyl-trimethyl-pyridinium chloride) and pyrene (Aldrich, USA) were used after purification [29]. Triple distilled water (conductance = 1 Â 10 À6 mho) was used throughout the experiments and were used within 7 days of its preparation.…”

“…The zeta potential of CTAB alone increases with increase of its concentration to a maximum value beyond which zeta potential decreases with further increase CTAB concentration. The formation of micelles limits the monomeric concentration of CTAB in the bulk [29] leading thereby to a maximum zeta potential value. The decease of zeta potential at higher concentration is due to the large size of the micelle and removal of the fraction of the charge as a result of aggregation.…”

Tunable biomimetic systems based on a novel amphiphilic pyrimidinophane and a helper nonionic surfactant

“…Such anionic-like behavior is sometime observed for nonionic surfactants with the large number of oxygen atoms in its skeleton in alkali solutions. It could be explained by the adsorption of OH-anions near the polyoxyethylene (PEO) mantle of the surfactant [33][34][35]. Thus, 1 and TX-100 aggregates have significantly different zeta-potentials.…”

Micropartioning and solubilization enhancement of 1,2-bis(bis(4-chlorophenyl) methyl)diselane in mixed micelles of binary and ternary cationic–nonionic surfactant mixtures

“…The value of cationic surfactant is positive as well as increases with increase of its concentration to a maximum value beyond which becomes approximately constant with further increase in surfactant concentration. The formation of micelles limits the monomeric concentration of surfactant in the bulk [44] leading thereby to a maximum value. The constancy of at higher surfactant concentration is due to the large size of the micelle and removal of the fraction of the charge as a result of aggregation.…”