Ecological synthesis of nickel–zinc–aluminium layered double hydroxides (Ni–Zn–Al LDH) in flow infrared radiated agitated tubular reactor (flow-IR-ATR).

The yield of obtaining layered double hydroxides (LDHs) remains a significant challenge that limits their practical use on a large scale. The use of flow processes is an innovative approach to solving the problem. This paper describes a method for obtaining LDH nanoparticles using an agitated tube reactor heated by infrared radiation (flow-IR-ATR). As a dedicated reactor for production of LDH nanoparticles, it is able to synthesise products at a flow rate of 1.8 dm3/h and a yield of 40 g/h. In the process, LDH NPs based on zinc–aluminium hydroxides (Zn–Al LDH) and LDH NPs modified with nickel hydroxide (Ni–Zn–Al LDH), with molar ratio of Ni to Zn 0.5, were obtained. Instrumental analyses (XRD, FTIR, SEM, DLS, BET, XPS) were used to characterise the LDH nanoparticles obtained, which showed crystallite sizes from 9 to 35 nm. The nickel-containing LDHs exhibited high photocatalytic activity. After 60 min, in the presence of UV radiation (365 nm), the photodegradation efficiency of quinoline yellow (dye concentration of 100 mg/dm3) was more than 99.9%. [ABSTRACT FROM AUTHOR]