Novel microwave-assisted multiwall carbon nanotubes enhancing Cu (II) adsorption capacity in water

Abstract

Microwave induced multiwall carbon nanotubes (MWCNTs) synthesized use a tubular microwave chemical vapor deposition technique, using acetylene and hydrogen as the precursor gases, and ferrocene as the catalyst. The novel MWCNT samples tested for performances in terms of Cu (II) binding were synthesized and characterized using BET,HRTEM,FESEM analysis and using this sample adsorption of Cu (II) they were studied as a function of pH, initial Cu (II) concentration, MWCNTs dosage, agitation speed, and adsorption time. The effect of process parameters for the adsorption of Cu (II) such as pH, MWCNTs dosage, agitation speed, and adsorption time was optimized. The adsorption data followed both Freundlich and Langmuir isotherms. On the basis of the Langmuir model, qm was calculated to be 99 mg/g for microwave-synthesized MWCNTs. In order to investigate the dynamic behavior of MWCNTs as an adsorbent, the kinetic data were modelled using the pseudo-second-order and second-order. Different thermodynamic parameters, viz., ∆H°, ∆S° and ∆G° have also been evaluated and it has been found that the adsorption was feasible, spontaneous and endothermic in nature. The statistical analysis reveals that the optimum conditions for the highest removal (99.9%) of Cu (II) are at pH 5.5, MWCNTs dosage 0.1 g, contact time 35 min and agitation speed of 160 rpm. Our results prove that microwave-assisted MWCNTs can be used as an effective Cu (II) adsorbent due to the high adsorption capacity as well as the short adsorption time needed to achieve an equilibrium.