Design of novel metal hydroxide bio-nanocomposite (CBCS@LDH) for the scavenging of ciprofloxacin (CPN) drug from its aqueous solution: Kinetic, isotherm, thermodynamic and reusability studies

Abstract

Contamination in water by the pharmaceuticals is a multiracial social health concern. Therefore, a greener approach towards environmental remediation is a necessity. The present study is intended in synthesizing novel metal hydroxide bio-nanocomposite using the co-precipitation method involving carbonized black cumin seeds and salts of copper sulphate, sodium carbonate, aluminium hydroxide and manganese sulphate forming a layer double hydroxide (CBCS@LDH) to absorb the antibiotic drug ciprofloxacin (CPN). The synthesized CBCS@LDH was characterized using FT-IR, XRD, FE-SEM, HR-TEM and EDX. The interaction of CPN with metal hydroxides bio-nanocomposite showed an equilibrium time of 120 ​min favored at pH 6.0. The uptake process followed the pseudo-second order kinetic model and best fitting values into Langmuir isotherm model inferred about the favorable monolayer adsorption of the CPN with qmax 526.31 ​mg ​g-1. The positive value of ΔH° indicated that the adsorption of CPN over CBCS@LDH was endothermic in nature having high value (53.61 ​kJ ​mol−1) thereby further suggesting the chemisorption mechanism. The positive value of ΔS° revealed the randomness at the solid-liquid interface and the negative values of ΔG° suggested that the adsorption of CPN on CBCS@LDH is spontaneous. The CPN showed efficacious reusability up to seven cycles employing 0.1 ​M (aq) ethanol. The adsorptive mechanism involved electrostatic interactions along with hydrogen bonding.

Keywords

• Ciprofloxacin (CPN)
• Carbonized black cumin seeds@layered double hydroxide (CBCS@LDH)
• Maximum adsorptive capacity
• Langmuir
• Mechanism