Removal of phenylalanine from water with calcined CuZnAl-CO3 layered double hydroxides

Cu–Zn–Al–CO3 layered double hydroxide (LDH), with a Cu to Zn mole ratio of 5:1 and a (Cu+Zn) to Al mole ratio of nearly 2, was prepared and its calcined product (CLDH) was obtained. Batch sorption studies were conducted to investigate removal of phenylalanine from water with CLDH. The results show that CLDH can be used as an effective adsorbent and its sorption capacity is higher than that of Mg–Al–CO3–LDH. The maximum adsorption was observed at pH 6.7. A maximum adsorption capacity is 37.25 mg/g. The adsorption processes follow the Lagergren's first order kinetic model. The adsorption data are fitted well with the Langmuir isotherm equation. The thermodynamic parameters were calculated, and the negative ΔΘ and positive ΔΘ indicate that the adsorption processes are spontaneous endothermic in nature. The mechanism of adsorption also suggests that the benzoate molecules are tilted, forming an angle with the hydroxyl layers.