Functionalization of the surface of ceramic membranes with 3-mercaptopropyl groups using the sol-gel method

Tailoring Nanoadsorbent Surfaces: Separation of Rare Earths and Late Transition Metals in Recycling of Magnet Materials

“…However, acid-treated SiO 2 with L3 ( SiO 2 _L3_acid ) and L5 ( SiO 2 _L5_acid ) showed improved adsorption by increasing their maximum capacities by twice for Co, Nd, Sm, and by almost five times in the case of Ni. According to the literature, sulfur- and amine-containing groups possess higher selectivity towards LTM, which can explain the higher adsorption capacities towards Ni and Co for most of these ligands [ 43 , 44 , 45 , 46 , 47 , 48 ].…”

Modification of Ceramic Membranes by Silica Nanoparticles with Thiourea Functions

“…Since porous materials with thiourea groups in the surface layer are proved to be perspective for the sorption of heavy metal ions from aqueous solutions, we made an attempt of introduction these groups in the structure of the functionalizing layer of planar ceramic membranes. However, the procedure for the surface layer deposition was similar to the functionalization of membranes with mercapto groups, as described in [21] for planar ceramic membranes and in [19,22] for tubular ones. We used the reaction of hydrolytic copolycondensation of TEOS (as a structure-forming agent) and ETUS (as a source of functional thiourea groups) to form polysiloxane active membrane layers.…”

“…Because of sufficient viscosity of the original sol, it was diluted with ethanol to facilitate the formation of a homogeneous polysiloxane layer on the membrane surface (Table 1). Such procedure of sol dilution with ethanol earlier are proved effective for the formation of uniform active layers with SH groups [19,21]. However, due to the hydrophobicity of the resulting samples with thiourea groups and their poor permeability to water, optimal for the functionalization of planar supports appeared to be nine times the dilution of the original TEOS/ETUS sol.…”

“…Before functionalization, the tubular membrane supports were activated as described in [19]. They were boiled in 0.1 N HCl for 5 h, washed with water (about 2 L) until neutral pH values, and dried in a muffle furnace at 320°C for 6 h. In order to functionalize tubular membrane supports, an excess of sol (about 15 mL) was put in contact with the inner surface of the ceramic membrane for the period of 5 min.…”

“…It appears that the flux through the membranes functionalized with sol nine times diluted with ethanol (TU2) is higher than that through the membrane functionalized with sol five times diluted with ethanol (TU1) (see Figure 6(b)). Such phenomenon may be explained by the formation of a more uniform surface layer in the case of more diluted sol (TU2), as it was observed for thiol-functionalized membranes in [19]. Therefore, nine times sol dilution was used in the further experiments.…”