Modelling and optimization of gold mine tailings based geopolymer by using response surface method and its application in Pb2+ removal

Abstract

Besides that today's technology provides lots of developments and benefits, it also causes environmental pollution problems. Preventing environmental pollution and cleaning of pollutants are very important issues in terms of life. The first aim of this study is the synthesis and characterization of a geopolymer, which has a porous structure, from Bergama gold mine tailings. In this way, it is desired to eliminate the negative environmental effects caused by the gold mine waste. For this purpose, geopolymer samples were synthesized in accordance with the experimental program which was designed by Design Expert Trial 7 and optimum geopolymer sample was determined by Central Composite Inscribed (CCI) design method. The second aim of this study is to use the synthesized geopolymer sample in the adsorption of Lead (Pb2+). For this reason, various adsorption studies (pH, temperature, concentration, etc.), isotherm and kinetic studies have been done. X-ray fluorescence spectrometer (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscope-Energy-dispersive X-ray (SEM-EDX) and Brunauer-Emmett-Teller (BET) analyses were carried out for the raw materials and geopolymer characterization during the studies. ICP-OES device was used in adsorption studies. The experimental results showed that Pb2+ removal by gold mine tailings based geopolymers was best fitted to Langmuir isotherm model (R-2 = 0.999) and pseudo second order kinetic models (R-2 = 0.993). (C) 2019 Elsevier Ltd. All rights reserved.