Synthesis and inhibition behavior of acid stimuli-responsive Ca-Na2MoO4-HNTs nanocomposite

Halloysite nanotubes (HNTs) are the natural clay mineral with a tubular structure, which can be used as the nanocontainer for loading corrosion inhibitor . In this work, Na 2 MoO 4 was loaded into HNTs (defined as “Na 2 MoO 4 -HNTs”) through vacuum negative pressure method. In order to control the release rate of Na 2 MoO 4 from Na 2 MoO 4 -HNTs, the insoluble CaMoO 4 complex was introduced at the end of tubes through the interaction between Na 2 MoO 4 and Ca 2+ to obtain Ca-Na 2 MoO 4 -HNTs. The surface morphology was investigated by transmission electron microscope (TEM), and the release behavior was determined by UV–vis spectrophotometer . The inhibition behavior of Ca-Na 2 MoO 4 -HNTs for Q235 steel in 3.5% NaCl solution was investigated by electrochemical impedance spectrum techniques. The results show that Ca-Na 2 MoO 4 -HNTs owns insoluble CaMoO 4 complex capping the end of HNTs, and the total loading capacity of Na 2 MoO 4 is about 14.6%. Moreover, the tunable release of Na 2 MoO 4 can be achieved by controlling the strength of the CaMoO 4 complex stoppers at the end of HNTs, and the release time of Na 2 MoO 4 can be prolonged to more than 600 min. Importantly, the release rate of Na 2 MoO 4 will increase sharply in acid solution, owing to the decomposition of CaMoO 4 complex. In addition, Q235 steel in 3.5% NaCl solution + 1.0 g/L Ca-Na 2 MoO 4 -HNTs exhibits higher inhibition efficiency (60.62% at 24 h) than Q235 steel in 3.5% NaCl solution.