Abstract
Pollution due to the presence of nickel is of great importance because of its toxic nature and non-biodegradability. Nickel is one of the most common heavy metals used in the industry. The purpose of the study is to investigate the efficiency of modified multi-walled carbon nanotubes (MWCNTs) on the adsorptive removal of nickel (II) from its aqueous environment and also to survey the applicability of the linear and nonlinear adsorption kinetic models on the process. The effects of process parameters including pH (4, 5, 7, and 10), MWCNT dosage (2.5, 5, 10, and 12 mg/L), initial nickel (II) ion concentration (25, 50, 100, and 125 mg/L) and contact time (5, 10, 25, and 40 min) on the removal efficiency of nickel using MWCNTs were studied, and their optimum conditions were also determined. Maximum nickel removal efficiency of 82% was observed at the optimum conditions of pH 10, MWCNT dosage of 10mg/L, initial nickel concentration of 100 mg/L and contact time of 10 min. The experimental data fitted best into the linear Ho (I) kinetic models than the other linear models. The rate-determining step of the process was found to be chemisorption. The correlation coefficient R2 values obtained for the linear and nonlinear models revealed that the nonlinear Ho adsorption kinetic provided a better explanation of the adsorption kinetic data of nickel removal by MWCNTs.
Highlights
Heavy metals are persistent in the environment and have led to many problems (Zhang et al 2010)
The aim of this study is to investigate the applicability of multi-walled carbon nanotubes on the removal of nickel(II) ions from its aqueous solution and to investigate the effects of different environmental factors such as pH, MWCNTs dosage, initial concentration of nickel, and time of treatment on the adsorption process
In order to determine the exact diameter of MWCNTs, some information about the morphology of absorbent surface was provided by means of a scanning electron microscopy, SEM (HITACHI Model S-3000H)
Summary
Heavy metals are persistent in the environment and have led to many problems (Zhang et al 2010). They enter into the aquatic ecosystems and can accumulate in tissues and organs of aquatic organisms which are being eventually introduced into the food chain (Agarwal et al 2016). Nickel is one of the most common heavy metals; it is applied in many industrial processes including steel manufacturing and electroplating
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