Adsorption kinetics and thermodynamics of sodium butyl xanthate onto bornite in flotation

In this paper,the effect of sodium butyl xanthate(NaBX)adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic.The flotation results demonstrated that the recovery was the highest when pH was 9 in NaBX solution(4×10^?5 mol/L).The adsorption kinetics showed the reaction of NaBX on the bornite conformed to the second order kinetic equation;it belonged to the multimolecular layer adsorption of Freundlich model;the maximum adsorption rate constant was 0.30 g/(10^?6 mol·min),and the equilibrium adsorption capacity was 2.70×10^?6 mol/g.Thermodynamic calculation results indicated that the adsorption process was spontaneous chemisorption,and the adsorption products of NaBX on bornite surface were cupric butyl xanthate,ferric butyl xanthate and dixanthogen,which were confirmed by infrared spectrum measurements.

Preparation of Waste Coffee-grounds Carbon and Study on Phenol Adsorption Ability

The waste coffee-grounds carbon(WCGC)was prepared with H_(3)PO_(4)treated using waste coffee-grounds as precursor.Its adsorption ability was studied using phenol as test molecule.The influence of H_(3)PO_(4)treated,calcined temperature,the initial phenol concentration,the doge of carbon and original pH values on phenol adsorption ability were investigated.Characterization of WCGC was performed by N_(2)adsorption isotherms,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),and X-ray diffraction(XRD)techniques.First,the second order and Weber-Morris model reaction rate models were used to estimate the WCGC adsorption ability.The results show that the produced WCGC(700℃,2 h)has been graphitized and the layered structure increased BET surface to 435.98 m^(2)/g and adsorption phenol ability.The initial phenol concentration is 50 mg/L,the amount of WCGC(700℃,2 h)is 0.2 g,and the phenol adsorption rate is 97%after 270 min and no intermediate product formation.The adsorption kinetics of the selected WCGC is best fitted by the Weber-Morris model.

Linear Viscoelasticity of ABA-type Vitrimer Based on Dioxaborolane Metathesis

In this study,we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct.The vitrimer samples thus prepared exhibit linear viscoelasticity dependent on the length of A moiety as well as the content of the crosslinks.When the average number of A monomers per end moiety m=1.1,the crosslinker can only extend the chain but not crosslink the chain.When m becomes 2.8 or higher,introducing a crosslinker first leads to the gelation,whereas excess in crosslinker molecules leads opening of the crosslinking sites and accordingly reentry into the sol regime.Surprisingly,a further increase in the length of the A moieties increases the relaxation time much weaker than the exponential increase seen for the physically crosslinked ABAtype ionomers.We attribute this difference to the distinct relaxation mechanisms:the relaxation of the vitrimer samples is based on relatively independent exchange reactions,which contrasts with the ABA-type ionomers that relax through the collective hopping of connected ionic groups from one ion aggregate to another.