Abstract

Farveh Raoufi, Hossein Aghaee and Majid Monajjemi* 

DOI : http://dx.doi.org/10.13005/ojc/320412

In this study, adsorbent was synthesized by covalently anchoring N-(3-nitro-benzylidene)-N-trimethoxysilylpropyl-ethane-1, 2-diamine onto multi-walled carbon nanotubes (NBATSPED-MWCNTs). This novel material was characterized by different techniques such as XRD, SEMand FT-IR.Subsequently, itwasusedfortheultrasound-assisted removalofAura mine O(AO) and Crystal violet (CV) from aqueous solutions was investigated. The dependency of removal percentages to variables such as pH, initial dyes concentration,adsorbent dosage, sonication time on the removal percentages ofAO and CV were simultaneously investigated by central composite design (CCD) under response surface methodology (RSM). It was shown that the adsorption of AO and CV follows the pseudo-second-order rate equation, while the Langmuir model explains equilibrium data. Isotherms had also been used to obtain the thermodynamic parameters such as free energy (ΔG^°), enthalpy (ΔH^°) and entropy (ΔS^°) of adsorption. The negative value of ΔG^° indicates the feasibility and spontaneity of the adsorption process. The positive ΔH^° suggests the endothermic nature of the adsorption. The positive values of ΔS₀ reflect the affinity of multi-walled carbon nanotubes functionalized towards CV and AO. A small amount of the adsorbent was able to remove more than 99.20% of both dyes rapidly with high adsorption capacity in binary-component system (69.36 mgg^-1 and 120.65mg g^-1for AO and CV respectively).

multi-walled carbon nanotubes; Response surface methodology; Ultrasound-assisted dye removal; Crystal Violet; Aura mine O

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