Adsorption of Metal Ions from Single and Binary Aqueous Systems on Bio-Nanocomposite, Alginate-Clay

Abstract

The aim of this work is to characterize and evaluate the retention of Cu2+ and Ni2+ from single and binary systems by alginate–−Moroccan clay bio−composite with the utilization of calcium chloride as a cross−linking agent, using the ionotropic gelation method. The bio−nanocomposite was characterized by using a variety of techniques (SEM, EDX, XRD, and pHPZC). The efficiency of the adsorbent was investigated under different experimental conditions by varying parameters such as pH, initial concentration, and contact time. To demonstrate the adsorption kinetics, various kinetic models were tried and assessed, including pseudo−first−order, pseudo−second−order, intraparticle diffusion, and Elovich models. The research results show that the adsorption process of Cu2+ and Ni2+ metal ions follows a pseudo−second−order kinetic model, and the corresponding rate constants were identified. To evaluate the parameters related to the adsorption process in both single and binary systems, different mathematical models of isotherms, such as Langmuir, Freundlich, Temkin, and Dubinin–−Radushkevich, were investigated. The correlation coefficients obtained showed that the most suitable isotherm for describing this adsorption process is the Langmuir model. The process is considered to be physical and endothermic, as suggested by the positive values of ΔH° and ΔS°, indicating increased randomness at the solid/liquid interface during Cu2+ and Ni2+ adsorption. Furthermore, the spontaneity of the process is confirmed by the negative values of ∆G°. The bio−nanocomposite beads demonstrated a maximum adsorption capacity of 370.37 mg/g for Ni2+ and 454.54 mg/g for Cu2+ in the single system. In the binary system, the maximum adsorption capacities were observed to be 357.14 mg/g for Ni2+ and 370.37 mg/g for Cu2+. There is significant evidence for the use of alginate–−Moroccan clay bio−nanocomposite as a cost−effective alternative adsorbent for the efficient removal of metal ions in single and binary systems.

Recent Progress on the Adsorption of Heavy Metal Ions Pb(II) and Cu(II) from Wastewater

“…There is also much research on Cu(II) adsorption nanocomposites. Aziam [ 6 ] prepared alginate–Moroccan clay bio composites. The results show that the adsorption processes of Cu 2+ and Ni 2+ metal ions conform to the quasi-second-order kinetic model, and the corresponding rate constants are determined.…”

“… SEM images of ( a ) alginate–Moroccan clay bio-nanocomposite microparticles (reproduced with permission from Ref. [ 6 ] from MDPI), ( b ) chitosan/poly(vinylalcohol)/ZnO beads (reproduced with permission from Ref. [ 128 ] from Elsevier), ( c ) magnetic chitosan/cellulose nanofiber-Fe(III) composite (reproduced with permission from Ref.…”

“…The wastewater from industrial production is the main source of heavy metal ions. During the past half-century, people realized that the accumulation of PPb levels of heavy metal ions can cause serious diseases in the human body and the amount of heavy metal is gradually enriched in the biological body along the food chain with irrigation, drinking water and other ways [ 4 , 5 , 6 ].…”

“…Figure12. SEM images of (a) alginate-Moroccan clay bio-nanocomposite microparticles (reproduced with permission from Ref [6]. from MDPI), (b) chitosan/poly(vinylalcohol)/ZnO beads (reproduced with permission from Ref [128].…”