Preparation of amino functionalized imidazolium-modified silicas by different coupling agents for removal of 2,4-dinitrophenol from aqueous solutions

Abstract

Amino group exhibits alkaline properties. Amino functionalized imidazole-modified silicas would benefit the adsorption of phenolic compounds. Coupling agent between the silica and the imidazolium ring has an effect on adsorption performance. In this paper, two adsorbents were synthesized for the surface bonding of N-(3-aminopropyl)-imidazole onto silicas modified by 3-chloropropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane, respectively. Infrared spectra, elemental analysis, thermogravimetric analysis and N 2 adsorptiondesorption isotherms were used to characterize the two adsorbents, and their adsorption capacities of 2,4-dinitrophenol from aqueous solutions were investigated in detail. The experimental results indicated that amino group plays an important role in the enhancement of adsorption capacities of 2,4-dinitrophenol. The adsorbent with 3-mercaptopropyltrimethoxysilane as coupling agent exhibited lower adsorption capacity due to a weak electron-electron repulsion between the non-bonding electrons of sulfur atom and p electrons of benzene ring of 2,4-dinitrophenol. The adsorption kinetics fitted well with pseudo-second-order model. The two adsorbents could be regenerated and reused eight times at least by washing with HCl. The adsorption mechanism was also discussed.

Mono and co-immobilization of imidazolium ionic liquids on silica: effects of the substituted groups on the adsorption behavior of 2,4-dinitrophenol

“…All adsorption and desorption experiments were conducted using the same method in our previous reports. [47][48][49]…”

“…The Langmuir maximum adsorption capacity for the ve adsorbents followed the order: SilprAImCl > SilprDBImCl > SilprNImCl > SilprBImCl > SilprDAImCl. Compared with other adsorbents such as granular activated carbons impregnated with phosphoric acid (299.6 mg g À1 ), 17 UiO-66-NH 2 (29.6 mg g À1 ), 19 carbon nanospheres (32.9 mg g À1 ), 25 SilprImCl (33.3 mg g À1 ), SilprM 1 ImCl (33.9 mg g À1 ), SilprM 2 ImCl (35.9 mg g À1 ), SilprM 4 ImCl (37 mg g À1 ), SilprM 1 M 2 ImCl (35.3 mg g À1 ), 47 SilprP 3 NImBr (91.74 mg g À1 ) and SilprSP 3 NImBr (51.81 mg g À1 ), 49 the ve adsorbents in this study possessed a high 2,4-DNP adsorption capacity.…”

“…The reported adsorbents include carbons activated by KOH, HNO 3 H 3 PO 4 and ZnCl 2 , 17 olive wood biosorbents, 18 UiO-66-NH 2 , 19 glycidyl methacrylate graed cotton cellulose, 20 yellow bentonite, 21 XAD-4 resin, 22 activated carbon bers, 23 layered double hydroxides and their calcined products, 24 carbon nanospheres, 25 date seeds 26 and active carbon. 27 In recent years, ionic liquid-modied silicas (IL-silicas) as adsorbents have been widely used to remove Cu(II), Fe(III), Mn (II) and Ni(II), 28 Pb(II), [29][30][31] Cr(III,VI), [32][33][34] lanthanides and scandium ions, 35 oxymatrine, 36 bovine serum albumin, 37 racemic amino acids, 28 thiophenic sulfur compounds, 38 anionic dye, 39,40 dibenzothiophene 41 and phenolic compounds (4-chlorophenol, 42 polyphenols, 43 phenolic acids, 44 naphthols, 45 bisphenol A 46 and 2,4-DNP [47][48][49] ). To elucidate the relation between the structure of IL-silicas and their adsorption performance for phenolic compounds, a series of IL-silicas were designed by varying substituents, the functional groups of the imidazolium ring, counter ions and silane-coupling agents.…”

“…However, the adsorption ability of the adsorbent prepared using 3-mercaptopropyltrimethoxysilane as the coupling agent decreased signicantly. 49 In order to overcome the negative effects of coexisting anions on the adsorptive removals of naphthols, a silica adsorbent was prepared through the co-modication of 1-vinyl-3octadecylimidazolium cations and p-styrenesulphonate anions on silica via click chemistry reaction. 45 In addition, imidazole, phenyl and hexadecyl were further co-immobilized onto silica via silane coupling reaction or thiol-ene click chemistry for bisphenol A adsorption from high salt aqueous solutions.…”

Selective and Adjustable Removal of Phenolic Compounds from Water by Biquaternary Ammonium Polyacrylonitrile Fibers

“…Among these approaches, adsorption methods have aroused considerable interest owing to their simplicity, efficiency, and low cost . Till now, various adsorbents including silica gels, , metal–organic frameworks, and activated carbon , have been used to remove 2,4-DNP from an aqueous solution. However, some of these adsorbents have the disadvantages of high cost, a tedious preparation process, and unsatisfactory recyclability, which hinder their practical applications.…”