Surface modification of alumina nanofibres for the selective adsorption of alachlor and imazaquin herbicides

Abstract

The effective removal of pollutants using a thermally and chemically stable substrate that has controllable absorption properties is a goal of water treatment. In this study, the surfaces of thin alumina (γ-Al(2)O(3)) nanofibres were modified by the grafting either of two organosilane agents, 3-chloro-propyl-triethoxysilane (CPTES) and octyl-triethoxysilane (OTES). These modified materials were then trialed as absorbents for the removal of two herbicides, alachlor and imazaquin from water. The formation of organic groups during the functionalisation process established super hydrophobic sites on the surfaces of the nanofibres. This super hydrophobic group is a kind of protruding adsorption site which facilitates the intimate contact with the pollutants. OTES grafted substrate were shown to be more selective for alachlor while imazaquin selectivity is shown by the CPTES grafted substrate. Kinetics studies revealed that imazaquin was rapidly adsorbed on CPTES-modified surfaces. However, the adsorption of alachlor by OTES grafted surface was achieved more slowly.

Nanofiber-Based Materials for Persistent Organic Pollutants in Water Remediation by Adsorption

“…The higher performance of organosilane-grafted clays and alumina nanofibers suggests that there is competition between adsorption via hydrophobic interactions and via electrostatic interactions as the most efficient mechanism for Alachlor uptake [28,29]. Indeed, organosilane grafting provides the adsorbent with a hydrophobic surface more amenable to pesticides [28]. Each adsorbent reported in this study for the adsorption of Alachlor differs in both structure and composition.…”

“…Nanofiber adsorbents made of alumina with surface-grafted organosilanes showed the second best performance with 58% removal for a specific surface area of 252 m 2 /g ( Table 2, N1). The higher performance of organosilane-grafted clays and alumina nanofibers suggests that there is competition between adsorption via hydrophobic interactions and via electrostatic interactions as the most efficient mechanism for Alachlor uptake [28,29]. Indeed, organosilane grafting provides the adsorbent with a hydrophobic surface more amenable to pesticides [28].…”

“…Concerning the adsorbent pore size, not enough data were found in the literature to enable a study of a preferential pore diameter for a specific pollutant among the ones considered in this section. In the case of Alachlor adsorption, organosilane-grafted beideillite clay and alumina nanofibers were reported to have a pore diameter of 6.44 nm and 11.4 nm, respectively, and showed an efficiency of 80% and 58% (Table 2, N1, N5) [28,29]. These results may suggest that an 11.4 nm wide pore channel does not offer enough promiscuity for the adsorption of Alachlor molecules, combined with a possible decrease in the efficiency of silane grafting along the adsorbent pore walls, thus impeding adsorption via hydrophobic interactions.…”

“…Regarding adsorbent surface chemistry, a total hydrophobic surface is preferable to show affinity for adsorption-in the case of surface grafting of hydrophobic groups, adsorption may be impeded along the pore walls [28]. Compared to hydrophobic interactions, electrostatic interactions and foremost electron interactions were shown to be more efficient adsorption mechanisms [41,113].…”

Influence of concentration modifier on the structure and functional properties of aluminum oxyhydroxide modified

“…It is known that the scope of the nanoparticles is determined by their properties, so the preparation of nanoparticles with new properties is the actual direction of science and technology. Giving new properties of aluminum oxyhydroxides can be due to its modification [8,9]. Due to the very small size of the material surface modification can not be accomplished, however, the volume in the modification process of direct synthesis of the material can be realized.…”