Synthesis and characterization of PPy@NiO nano-particles and their use as adsorbent for the removal of Sr(II) from aqueous solutions

In this work, PPy@NiO nanoparticles were synthesized and characterized by XRD, ATR-FTIR, SEM and TEM methods. Synthesized nanoparticles were used for the adsorption of Sr2+ ions from aqueous solutions. The factors influencing Sr2+ adsorption, such as adsorbent dosage, pH and initial concentration, were optimized using the central composite design (CCD) of response surface methodology (RSM). The experimental and model predicted values of response (removal %) were in good agreement and ANOVA study suggested that the developed second-order polynomial model is highly significant. The F and P values revealed that this regression is statistically significant. The response optimization plot showed that 98% Sr2+ removal can be achieved by keeping the metal concentration, pH and dose, 34.6 mg/L, 11.0 and 0.9 g/L respectively. The kinetic studies revealed that the adsorption of Sr2+ ions on PPy@NiO nanoparticles was rather rapid and Sr2+ adsorption followed pseudo -second-order model. The maximum adsorption capacity of adsorbent was determined to be 258 mg/g. In this study RI, values for Sr2+ adsorption on PPy@NiO nanoparticles were less than 1 and greater than 0 for selected Sr2+ concentrations, which indicate the favourable adsorption of Sr2+ on nanoparticles. Thermodynamic parameters suggested that Sr2+ adsorption is spontaneous and endothermic in nature. Present study suggested that PPy@NiO nanoparticles can be efficiently used for the adsorption of Sr2+ ions, (C) 2016 Elsevier B.V. All rights reserved.