Characterization of the adsorption behavior of aqueous cadmium on nanozero-valent iron based on orthogonal experiment and surface complexation modeling

Polyvinylpyrrolidone K-30 (PVP) was introduced into the preparation of nanozero-valent iron (nZVI) and the traditional liquid-phase reduction was improved. The introduction of PVP simplified the traditional method. The nZVI prepared with this new approach showed excellent surface characters and high performance on the removal of cadmium. TEM results showed that the aggregates of nZVI can reach to several micrometers in length but less than 100 nm in diameter. The iron particles that were enclosed by a layer of oxide film that is less than 10 nm, demonstrated that the nZVI possesses a core-shell structure. BET results indicate that the specific surface area of the nZVI was 20.3159 m(2) g(-1). A three factor and three level orthogonal experiment was employed to find out the dominant factor that affects the removal rate of cadmium by nZVI. Based on the range values, the prominence order of each factor was: initial pH of the solution > initial concentration of cadmium > dosage of nZVI, the range was 96.453, 3.294 and 1.747, respectively. A simulation was performed under the same condition and a same conclusion was derived, this consistence confirmed the validity of the conclusion that pH is the most significant factor that affects the adsorption efficiency. (C) 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.