Chitosan‐sodium lauryl ether sulfate particles and their use for adsorption of Cu(II) ions

Abstract

The synthesis of small particles through the interaction between chitosan (CS) and sodium lauryl ether sulfate (SLES) was studied. Depending on working condition, microparticles at atmospheric pressure and ultrafine particles at high pressure have been obtained. At atmospheric pressure, the microparticles were formed instantaneously when the CS solution was dripped into the SLES aqueous solution. To obtain ultrafine particles, the surfactant solution in contact with high pressure carbon dioxide was sprayed into chitosan solution. Fourier Transform Infrared Spectroscopy proves the interaction between the sulfate groups of SLES and the amino groups of CS. The Scanning Electron Microscopy reveals that the microparticles are quasi-spherical, but some of them can take the form of pellets depending on preparation conditions. The obtained microparticles were successfully used to uptake Cu(II) ions from aqueous solutions. The adsorption of Cu(II) depends on pH being maximum at pH 5 5.5. The kinetic experiments demonstrated that Cu(II) adsorption onto CS/SLES microparticles obeys the Langmuir model.

Co-assembly in chitosan–surfactant mixtures: thermodynamics, structures, interfacial properties and applications

“…In a first instance this causes a rather limited solubility of the mixtures which can be exploited for the preparation of capsules [75,76,80,81,102,104,[214][215][216]. These capsules were shown to be able to efficiently adsorb metal ions such as Cu(II) [76] as well as organic dyes [215,216] but they can also be employed as drug carrier systems [80,214]. For instance, chitosan-SDS complexes were shown to efficiently protect insulin in the gastric tract from digestive enzymes [214].…”

“…Accordingly, authors reported the formation of μm sized droplets by emulsification of the chitosan solution in decane before admixing [102]. Even smaller capsules (radius of 200-250 nm) were obtained by spraying a surfactant solution under high pressure (up to 5 MPa) into a chitosan solution [76]. The initial increase in wall thickness of the droplets δ follows a t 0.5 power law [102], i. e., is diffusion controlled.…”

“…Chitosan strongly interacts with sulfated surfactants, forming waterinsoluble and structured complexes over a wide range of concentrations and mixing ratios [67,69,76,101,102] (see Fig. 3).…”

“…An apparent diffusion coefficient D = 10 −13 − 10 −12 m 2 s −1 (corresponding to a hydrodynamic radius of 0.25-2.5 μm) for chitosan can be estimated from the relation δ t ð Þ ¼ ffiffiffiffiffiffiffiffi 2Dt p [102]. The capsules were shown to be stable over long periods of time [76] and they can be used for a controlled release of enzymes [102], for the separation of metal ions [76] or organic pollutants [103].…”

“…However, they can be exploited for the preparation of microcapsules [75,76,102]. When chitosan is dropwise added to the surfactant solution, or viceversa, a capsule of the size of the droplet is formed by local ionic cross-linking of the polymer chains by the surfactant micelles.…”