Reusable high performance of calcined Mg/Al hydrotalcite for the removal of Navy Blue and Yellow F3G dyes

Water pollution with dye chemicals from apparel industries is a serious problem in the world. Since most of dyes are potentially have toxic and carcinogenic effects on human, it is important to remove them before they are discharged to the environment. Among many methods available for dyes removal in water, adsorption is the easiest and economically feasible that has no major obstacle for practical applications. In the present study, we tested calcined Mg/Al hydrotalcite (Mg/Al CHT) prepared by co-precipitation technique as an adsorbent for the removal of Navy Blue (NB) and Yellow F3G (YF3G) dyes. Mg/Al CHT was characterized by using a Fourier transform infrared (FTIR) spectrometer, an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The results showed that Mg/Al CHT was highly effective as an adsorbent for the removal of NB and YF3G under mild-acidic condition (pH 4) with removal capacities (b) according to Langmuir isotherm model were 7.97 × 10–4 and 5.80 × 10–4 mol·g−1, respectively. Kinetics study showed that the adsorption of NB and YF3D on Mg/Al CHT followed pseudo-second order with rate constant (kp2) 11.57 × 103 and 11.75 × 103 g·mol−1·min−1, respectively. The spent adsorbent can be easily regenerated by simply calcining it at 450 °C for 3 h. Adsorption test on the mixture of NB and YF3G showed that the adsorption capacity of Mg/Al CHT was eightfold higher than that of Mg/Al HT and the value was maintained with repeated use. © 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd