An innovative hybrid biosorbent composed of nano ZnO and marine macro algae Jania rubens embedded in an alginate/PVA matrix: insights into Pb2+ removal in water

Abstract

Nanoparticles of zinc oxide (ZnO) combined with a Jania rubens (JR) biosorbent have been embedded in a sodium alginate (SA)–polyvinyl alcohol (PVA) matrix. This hybrid biosorbent was characterized by FTIR, and the presence of functional groups involved in the adsorption of Pb²⁺ was revealed. SEM/EDX analyses have shown that the hybrid biosorbent exhibited porous microstructures which are decorated with ZnO nanoparticles (hydrodynamic size of 68 ± 2 nm). The removal of Pb²⁺ from aqueous medium was thoroughly investigated. The adsorption capacity has been measured at q_e = 39.1 mg g⁻¹ at pH = 5 and T = 303 K with the concentration of biosorbent and Pb²⁺ at 2.0 g L⁻¹ and 100 mg L⁻¹, respectively. The Freundlich and Langmuir isotherms have been used to model the adsorption process, from which the maximum adsorption capacity (q_m) of the hybrid biosorbent was calculated to be 111 mg g⁻¹. The adsorption kinetics are represented by a pseudo-second order model. In addition, the hybrid biosordent was regenerated and reused for four cycles for the removal of Pb²⁺.