Performance And Mechanism Of Copper Removal From Wastewater By Calcined Colloidal Pyrite

Colloidal pyrite, was collected from Xinqiao deposits in Tongling, Anhui. Thestructural evolution, magnetic susceptibility and arsenic content of colloidal pyritewere studied. The colloidal pyrite was heat-treated under N2atmosphere andcharaterized with X-ray powder diffraction (XRD), field emission scanning electronmicroscope (FE-SEM), magnetic susceptibility meter, and atomic fluorescencespectroscopy (AFS). Batch experiment was investigated on the physicochemicalfactors of Cu2+removal from aqueous using calcined colloidal pyrite (CCPy) underinert atmosphere, and the factors included calcined temperature, initial solution pH,initial Cu2+concentration, sorption time, sorption temperature and foreign ions.Besides, laboratory column tests were conducted to study and assess the potential ofcalcined colloidal pyrite (CCPy) as a low cost sorbent material to remove andrecover copper (Cu) from aqueous solutions. The X Ray Fluorescence (XRF), X-raydiffraction (XRD), field emission scanning electron microscopy (FE-SEM) image,X-ray photoelectron spectroscopy (XPS) and High Resolution TransmissionElectron Microscopy (HR—TEM) were used to characterize CCPy after sorption ofCu2+. The results indicated that:(1) phase transition behaviours of colloidal pyritehave occurred as it was firstly transformed into magnetite and monoclinic pyrrhotite,then hexagonal pyrrhotite, finally quartet pyrrhotite as well as the troilite whencalcined under inert atmosphere.(2) colloidal pyrite calcined at500-550°C was bestfor Cu2+removal. Increasing pH was propitious to the copper removal. The metalsorption yields also increased with the increasing initial concentration and contacttime, and reached to equilibrium at24h; the endothermic and spontaneous Cu2+sorption process on CCPy fitted the second-order quation well, which could be welldescribed by the Langmuir isotherm.(3) The throughput volume was up to1672bedvolumes (BV). The Cu2+sorption capacity of CCPy in the column test until thebreakthrough occurred was up to84mg Cu/g CCPy. The Cu content in the sorbentwas up to20%in the sorption equilibrium zone in the column; it also showed thatthe dissolution-precipitation was the main mechanism for Cu2+sorption on CCPy.