*2.2. Synthesis and Modification of m-LDH*

Zn-Ti LDH was synthesized by the co-precipitation method. TiCl<sup>4</sup> (0.44 mL), Zn(NO3)2·6H2O (4.76 g) and urea (6.0 g) were dissolved in deionized water, the mixture

was stirring at 95 ◦C for 48 h under nitrogen atmosphere. After preparation, the obtained insoluble (i.e., Zn-Ti LDHs) was washed by deionized water and ethanol, eventually dried at 80 ◦C in vacuum 24 h. The SA modification of Zn-Ti LDH was used by ion-exchange method. SA (0.2 M) and Zn-Ti LDH (0.5 g) were added into the deionized water. The solution controlled at pH = 10 to 11 by drop 0.1 M aqueous NaOH and stirring at 80 ◦C for 24 h under nitrogen atmosphere. The produced m-LDH was washed by deionized water and ethanol several times, then dried at 50 ◦C in vacuum 24 h.
