| 1. |
- Karlkvist, Tommy, et al.
(författare)
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Flotation selectivity of novel alkyl dicarboxylate reagents for calcite-fluorite separation
- 2016
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Ingår i: Tenside, Surfactants, Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 53:6, s. 516-523
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Tidskriftsartikel (refereegranskat)abstract
- A series of amino acid-based surfactants with a fixed alkyl chain length and with two carboxyl groups separated by a spacer of one, two or three carbon atoms have been synthesized and evaluated as potential collectors for flotation of calcite and fluorite. A monocarboxylate amino acid-based surfactant having the same length of the hydrocarbon tail was also included for comparison in the study. Experiments using a Hallimond flotation tube showed that although the flotation reagents solely differ in terms of spacer, their efficacy in terms of flotation recovery varied very much. Whereas on calcite at pH 10.5 only the monocarboxylate collector gave a high yield, on fluorite at the same pH both the monocarboxylate and the dicarboxylate collectors with one carbon between the carboxyl groups gave good results. On calcite at the natural pH the monocarboxylate collector was most efficient but the dicarboxylate collectors with a two and a three-carbon spacer also gave a reasonable recovery. On fluorite at the natural pH the dicarboxylate collectors with a two- and a three-carbon spacer were most efficient. The zeta-potential and the flotation recovery of the mineral particles as a function of added collector were assessed and the adsorption was also monitored by diffuse reflectance infra-red spectroscopy. Taken together, the results showed that small changes in the head group region of the collector can radically affect flotation recovery. This type of knowledge is important to understand flotation selectivity in a mixture of similar minerals.
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| 2. |
- Ranieri, Davide, et al.
(författare)
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On the Influence of Intersurfactant H-Bonds on Foam Stability : A Study with Technical Grade Surfactants
- 2018
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Ingår i: Tenside Surfactants Detergents. - : CARL HANSER VERLAG. - 0932-3414 .- 2195-8564. ; 55:1, s. 6-16
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Tidskriftsartikel (refereegranskat)abstract
- From the literature on the foam stability of various surfactants with C-12 alkyl chains but different head groups a clear picture emerges: Foams are more stable when hydrogen bonds can form between the head groups, i.e. when the polar head group has a hydrogen bond donor and a proton acceptor. These observations suggest that hydrogen bonds between neighbouring molecules at the surface enhance foam stability. To support this hypothesis, we carried out a systematic foaming study of two types of technical grade surfactants, one of them being capable of forming H-bonds and the other one not. As was the case for the pure surfactants we found again that more stable foams are formed when the head group is capable of forming intersurfactant H-bonds: These results will certainly affect the future design of surfactants.
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| 3. |
- Raykundaliya, Nirav, et al.
(författare)
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The effect on Solution Properties of Replacing a Hydrogen Atom with a Methyl Group in a Surfactant
- 2015
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Ingår i: Tenside, Surfactants, Detergents. - : Walter de Gruyter GmbH. - 0932-3414 .- 2195-8564. ; 52:5, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- Two surfactants, namely, dodecanoylglycinate and dodecanoylsarcosinate, differing only in a methyl group vs. a hydrogen atom on the amide nitrogen, have been studied with respect to solution behavior and adsorption at the air-water, oil-water and calcium carbonate-water interfaces. It was found that the ability of the glycinate surfactant of forming intermolecular hydrogen bonds via the amide group leads to tighter molecular packing, which greatly influenced the behavior at interfaces. Based on this molecular observation, potential applications were considered and emulsification, foaming and wetting tests were carried out. It could be concluded from this work that a minor change in the structure of a surfactant molecule can be very significant for technological systems and processes.
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