Preparation and Characterization of Silane Coupling Agent Modified Halloysite for Cr(VI) Removal

Abstract

Natural halloysite nanotubes (HNTs) were modified with a silane coupling agent, N-β-aminoethyl-γ-aminopropyl trimethoxysilane (KH-792), to form a new adsorbent for Cr(VI) removal. The as-prepared product was characterized by FTIR spectroscopy, TGA, TEM, and specific surface analysis. The results showed that KH-792 was successfully grafted onto the halloysite surface. Modified HNTs exhibited a rapid adsorption rate for Cr(VI) and approached 95% of the maximum adsorption capacity within 5 min. The effects of initial Cr(VI) concentration, temperature, pH, and ionic strength on the adsorption capacity were investigated in batch experiments. The results showed that low temperature was favorable to improve adsorption efficiency, and the adsorption capacity decreased significantly with the increase of pH and ionic strength. The optimum pH was found to be 3À5. The main adsorption mechanism was considered to be electrostatic interaction between protonated amino groups on the adsorbent surface and negatively charged Cr(VI). The results above confirmed that modified HNTs had the potential to be utilized as a low-cost and relatively effective adsorbent for Cr(VI) removal.

Polypyrrole-coated halloysite nanotube clay nanocomposite: Synthesis, characterization and Cr(VI) adsorption behaviour

“…Conventional methods used for the removal of Cr(VI) from aqueous solution are chemical precipitation, ion-exchange, membrane filtration, electrochemical process and adsorption (Faust and Aly, 1997;Aliane et al, 2001;Wojcik et al, 2011;Kaya et al, 2013). However, all these methods, except adsorption, have certain disadvantages like high operating cost, requiring high energy and large amounts of reagents, and the generation of toxic sludge (Bishoni et al, 2004;Luo et al, 2011). Amongst these, adsorption has been proven to be one of the best alternative techniques due to its simplicity, low cost and robustness (Atia, 2008;Sarkar et al, 2010).…”

“…Zhou et al prepared polymeric Fe/Zr pillared montmorillonite (Fe/Zr-Mt) with different Fe/Zr molar ratios (4:1 and 1:1) for the removal of Cr(VI) with maximum equilibrium uptake of 22.35 mg/g (Zhou et al, 2010). Silane coupling agent modified halloysite was used for the removal of Cr(VI) by Luo et al (2011). They found a maximum adsorption capacity of 37.25 mg/g (Luo et al, 2011).…”

Funcionalização E Caracterização Do Argilomineral Haloisita Para Remediação Ambiental

“…Desse modo, várias pesquisas vêm sendo desenvolvidas com o objetivo de empregar adsorventes naturais, como por exemplo, os argilominerais [2]. O argilomineral composto por nanotubos de haloisita têm atraído grande interesse devido a sua estrutura tubular oca e alta área superficial.…”

Synthesization, Characterization, and in vitro Evaluation of Cytotoxicity of Biomaterials based on Halloysite Nanotubes

“…Halloysite nanotubes (HNTs) have been recently used due to their unique properties such as their hollow tubular structure, high surface area, surface characteristics, and high biocompatibility [1][2][3][4][5][6]. HNT tubules consist of a two layered aluminosilicate clay (Al2Si2O5(OH)4·2H2O) with an external diameter of 50-80 nm, lumen diameter of 10-15 nm, and length of 1000 nm [7].…”

“…The tubes have multilayer walls with positively charged Al-OH functional groups on the inner surface, and with negatively charged Si-OH functional groups on the outer surface [8]. These characteristics make HNTs a great absorbent for both cationic and anionic molecules [1][2][3][4][5]. Furthermore, their nanosized lumen enables entrapping a range of active agents such as macromolecules, and proteins [9].…”