Stellerite-seeded facile synthesis of zeolite X with excellent aqueous Cd^(2+)and Ni^(2+)adsorption performance

Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investigated.The effects of p H,zeolite X dosage,contact time,and temperature on adsorption performance for Cd^(2+)and Ni^(2+)ions over were studied.The adsorption process was endothermic and spontaneous,and followed the pseudo-second-order kinetic and the Langmuir isotherm models.The maximum adsorption capacitiesfor Cd^(2+)and Ni^(2+)ions at 298 K were 173.553 and 75.897 mg.g-1,respectively.Ion exchange and precipitation were the principal mechanisms for the removal of Cd^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption.Ion exchange was the principal mechanisms for the removal of Ni^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption and precipitation.The zeolite X converted from stellerite zeolite has a low n(Si/Al),abundant hydroxyl groups,and high crystallinity and purity,imparting a good adsorption performance for Cd^(2+)and Ni^(2+)ions.This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd^(2+)and Ni^(2+)ions from aqueous solutions.

Immobilizing ultrafine bimetallic PtAg alloy onto uniform MnO_(2) microsphere as a highly active catalyst for CO oxidation

Herein,a facile glycol reduction route is successful employed to synthesize bimetallic Pt Ag alloys with homogeneous distribution of sizes and elements.Experimental studies reveal that the ultrafine Pt Ag alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO_(2)microsphere,which remarkably enhances the catalytic performances for CO oxidation.Importantly,quasi in-situ X-ray photoelectron spectroscopy(XPS)result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O_(2)molecules,and the oxygen vacancy sites could be replenished and excited by gas-phase O_(2).