Abstract
In this study, mesoporous silica nanoparticles (MSNs) were synthesised using the Stober method and functionalised with cysteine (MSN-Cys) for removal of Methylene Blue (MB) from aqueous solution using the batch method. The adsorbent nanoparticles were characterised by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIR, BET, and TGA. Several influential factors on the adsorption of MB onto the surface of MSN-Cys particles were investigated, including pH, initial concentration, and contact time. The adsorption capacity of MB from aqueous solution increased from circa 70 mg/g MSN-Cys in acidic media to circa 140 mg/g MSN-Cys in basic media. Adsorption isotherms and kinetic models of adsorption were used to clarify the adsorption process. The measured adsorption isotherm was fitted with a Freundlich model for all solutions, and the kinetic model was determined to be pseudo-second-order.
Highlights
Dyes are widely used in many industries, as food additives, colorings, printing, plastics, and leathers [1, 2]
mesoporous silica nanoparticles (MSNs) were synthesised by addition of TEOS in an aqueous solution of CTAB in the presence of ammonium hydroxide, with n-hexane as a pore-expanding agent. e template was extracted by the ion exchange method using HCl in methanol to allow reaction within the pores
GPTS was conveniently bonded to the surface of MSNs. e thiol group in cysteine can react with an epoxy group on the surface of MSNs in basic medium, producing MSNs that contained amine and carboxyl groups attached to a single carbon atom (Figure 1)
Summary
Dyes are widely used in many industries, as food additives, colorings, printing, plastics, and leathers [1, 2]. Dyes are chemically stable and difficult to decompose biologically, especially when they are present in water [3,4,5,6,7]. Biological, and chemical methods have been used to remediate organic dyes from wastewater, such as photodegradation, microwave catalysis, biodegradation [10], coagulation-flocculation [10], oxidation or ozonation [11, 12], membrane separation [13], and adsorption. Adsorption has been widely applied to porous materials such as activated carbons [15, 16], metal-organic frameworks (MOF) [17, 18], and mesoporous silica [19, 20]
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