Ultrasound-assisted method was used to synthesize magnetic Ca/Al layered double hydroxides,and decoloration efficiency of reactive brilliant red X-3B simulated dye wastewater was studied.The effect of adsorbent dosage,adsorption time,and initial pH was investigated on the decolorization efficiency of reactive brilliant red X-3B dye wastewater,and the Box-Behnken response surface methodology(RSM)was used to optimize the adsorption conditions.The experimental results show that when the adsorbent dosage is 7.6 g/L,the adsorption time is 32.3 min and the initial pH is 6.9,the theoretical maximum decolorization rate of the reactive brilliant red X-3B is 94.2%.Owing to the magnetic characteristics of the material,after adsorption,magnetic Ca/Al layered double hydroxides can be quickly recovered from the suspension in an externed magnetic field.Meanwhile,the adsorption property of regenerated magnetic Ca/Al layered double hydroxides was studied.After 3 adsorption-desorption cycles the matenial still had a good decoloration efficiency,indicating that the magnetic Ca/Al hydrotalcite is a potential new type of dye adsorbent.