INVESTIGATION OF ACQUISITION OF TRIPLE SULFURS FROM Pb(CH3COO)2-Na3AsO4-H2S-H2O SYSTEM BY HYDROCHEMICAL METHOD

Abstract

Acquisition conditions by hydrothermal method of triple sulfides from Pb(CH3COO)2-Na3AsO4-H2S-H2O system were investigated using X-ray phase (X-ray), Differential Thermal (DTA) and Scanning Electron Microscopy (SEM) analysis, TG analysis methods. It was determined that sediments were obtained containing Pb26+xAs12S44+x content in pH=1-6 range and Pb28-xAs12S46-x content (0,6 < x < 1,5) in pH=6-14 range. The durability limits of PbS, As2S5, As2S3, Pb(OH)2, and Na3AsO4 were determined, and pCb-pH (pCb- difference between initial and final concentrations of metal) diagram was formed. The results of the X-ray phase analysis methods indicate that when the precipitates having a Pb:As:S=1:2:4; 2:2:5 and 9:4:15 molar ratio (pH=1-6) are thermally processed in vacuum at 400 °C (~10-2 Pa) in a dual-zone regime, phases containing PbAs2S4, Pb2As2S5 and Pb9As4S15 are conveniently formed. All three compounds are composed of nanoparticles, and high adhesion between particles is observed. Depending on the pH, concentration, and temperature of the condition, a large number of different precipitates and layers are obtained in the Pb(CH3COO)2-Na3AsO4-H2S-H2O system. Based on TG analysis, the stoichiometric composition of PbAs2S4, Pb9As4S15, and Pb2As2S5 compounds was determined.

Keywords

• triple sulfur
• hydrochemical sedimentation
• semiconductor
• concentration
• phase
• micromorphology