Original calcium alginate beads with porous structure and high adsorption surface are proposed. The beads were synthesized using sodium alginate in the presence of sodium dodecyl sulfate as foaming agent, NaCl as porogen agent and CaCl 2 as cross-linker. They were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and Brunauer-Emmett-Teller method. The adsorption capacity of beads was tested with methylene blue (MB). The data show that the adsorption efficiency increases with the amount of beads, decreases with pollutant concentration, and is maximal at pH = 9. The adsorption is fast in the first 3 hours, and slows down thereafter. The kinetic results show that the adsorption of MB on alginate porous beads obeys the Langmuir model. A scheme of MB adsorption taking into account the ionic interactions with calcium alginate beads has been proposed.
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.
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