Immobilization of salicylic acid on Ni-Zn layered hydroxide salts

Ni-Zn Layered hydroxide salt (Ni-Zn LHS) has been synthesized from equimolar Ni(NO3)2 and Zn(NO3)2 by co-precipitation method using NaOH. The formation of layered assembly is confirmed in X-ray diffractogram, i.e. by the appearance of peaks at 2θ: 9.60°, 19.40°, 33.48°, and 59.76° which corresponds to diffraction plane (001), (003), (020), and (040), respectively. The synthesized Ni-Zn LHSs possessed the point of zero charge (pHpzc) at pH 8 and nitrate as the interlamellar ion. The incorporation of salicylic acid into LHS can extend the property of LHS as a reductive adsorbent in the application of metal recovery. The immobilization of salicylic acid on the Ni-Zn-LHS was successfully done and indicated the strong pH-dependent property. The immobilization of salicylic acid on Ni-Zn LHSs was optimum at pH 7 and followed better the Langmuir than Freundlich isotherm models with immobilization capacity 64.93 mg/g. After the immobilization of salicylic acid, the basal spacing of Ni-Zn LHSs did not enlarge indicating that the immobilized salicylic acid was on the outer layer without entering the interlayer and this immobilized salicylic acid was stable at medium pH range 3 to 9. © 2020 Trans Tech Publications Ltd, Switzerland.