A core-shell amidoxime electrospun nanofiber affinity membrane for rapid recovery Au (III) from water

An affinity membrane was prepared by coaxial electrospinning and amidoxime (AONFA), and it was applied to selectively recovery Au (III) from an aqueous solution. The static adsorption results showed that, when pH at 5, the maximum adsorption capacity of AONFA membrane for Au (III) was 509.3 mg·g^-1. AONFA membrane exhibit much higher affinity and selectivity towards Au (III) than other metal cations. The membrane could be regenerated effectively by mixture solution of thiourea and HCl, and the desorption ratio reached almost 100% after 4 hours desorption. The dead-end filtration results showed that, the membrane utilization efficiency and adsorption capacity can be improved by increasing the flow rate, while increasing the concentration shorted the breakthrough process and had little impact to adsorption capacity. We can flexibly adjust the flow rate and concentration according to the situation to obtain the maximum utilization efficiency of the membrane in filtration process. The dynamic adsorption capacity is higher than the static adsorption capacity. The adsorption mechanism for Au (III) is electrostatic adsorption and reduction. Thus, AONFA membrane filtration was demonstrated to be a promising method for continuous recover Au (III) from wastewater.     

A new facile electrochemical method for the synthesis of 4-(pyridine-2-ylthio)benzene-l,2-diols

Electrochemical oxidation of catechols (1a-1c) has been studied in the presence of 2-mercaptopyridine (3) as a nucleophile in water solution using cyclic voltammetry and controlled-potential coulometry. The results revealed that the quinones derived from catechols (1a-1c) participate in Michael addition reaction with 2-mercaptopyridine (3) and converted to the corresponding (pyridine-2-ylthio)benzene-l,2-diol derivatives (4a-4c), via an EC mechanistic pathway. The electrochemical synthesis of compounds 4a-4c has been successfully performed at a carbon rod electrode and in an undivided cell with good yields and high purity.