Abstract
The commercially available nanoscale zerovalent zinc (nZVZ) was used as an adsorbent for the removal of malachite green (MG) from aqueous solutions. This material was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The advanced experimental design tools were adopted to study the effect of process parameters (viz. initial pH, temperature, contact time and initial concentration) and to reduce number of trials and cost. Response surface methodology and rapidly developing artificial intelligence technologies, i.e., artificial neural network coupled with particle swarm optimization (ANN-PSO) and artificial neural network coupled with genetic algorithm (ANN-GA) were employed for predicting the optimum process variables and obtaining the maximum removal efficiency of MG. The results showed that the removal efficiency predicted by ANN-GA (94.12%) was compatible with the experimental value (90.72%). Furthermore, the Langmuir isotherm was found to be the best model to describe the adsorption of MG onto nZVZ, while the maximum adsorption capacity was calculated to be 1000.00 mg/g. The kinetics for adsorption of MG onto nZVZ was found to follow the pseudo-second-order kinetic model. Thermodynamic parameters (ΔG0, ΔH0 and ΔS0) were calculated from the Van’t Hoff plot of lnKc vs. 1/T in order to discuss the removal mechanism of MG.
Highlights
The discharge of dyes and pigments from various industries has generated large quantities of colored wastewater, which pose a potential threat to the environment [1,2,3,4]
The commercially available nanoscale zerovalent zinc (nZVZ) was characterized by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)
Comparison between the experimental and prediction values obtained by the Response surface methodology (RSM) and the Back propagation (BP)-Artificial neural networks (ANNs)
Summary
The discharge of dyes and pigments from various industries has generated large quantities of colored wastewater, which pose a potential threat to the environment [1,2,3,4]. (shown in Figure 1) is a cationic dye belonging to the triphenylmethane dye category, which is widely used for dyeing of textile, leather and paper, printing, and treating parasites, fungal and bacterial infections in fish and fish eggs [5]. This noxious dye can cause carcinogenic, mutagenic and teratogenic effects on humans and animals [6,7,8,9]. Thereby, the removal of MG from wastewater before being discharged into surface water bodies is indispensible and significant.
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