Adsorption and desorption studies of &amp;lt;i&amp;gt;Delonix regia&amp;lt;/i&amp;gt; pods and leaves: removal and recovery of Ni(II) and Cu(II) ions from aqueous solution

Bolanle M Babalola,Ekemena O Oseghe,Olayide S Lawal,Adegoke O Babalola,Cecilia O Akintayo,Lukman S Akinola,Sunday F Abimbade,Olushola S Ayanda

doi:10.5194/dwes-13-15-2020

Adsorption and desorption studies of &lt;i&gt;Delonix regia&lt;/i&gt; pods and leaves: removal and recovery of Ni(II) and Cu(II) ions from aqueous solution

Bolanle M Babalola, Ekemena O Oseghe + Show 6 more

Open Access

https://doi.org/10.5194/dwes-13-15-2020

Copy DOI

Abstract

Abstract. In this study, the adsorption of Ni(II) and Cu(II) ions from aqueous solutions by powdered Delonix regia pods and leaves was investigated using batch adsorption techniques. The effects of operating conditions such as pH, contact time, adsorbent dosage, metal ion concentration and the presence of sodium ions interfering with the sorption process were investigated. The results obtained showed that equilibrium sorption was attained within 30 min of interaction, and an increase in the initial concentration of the adsorbate, pH and adsorbent dosage led to an increase in the amount of Ni(II) and Cu(II) ions adsorbed. The adsorption process followed the pseudo-second-order kinetic model for all metal ions' sorption. The equilibrium data fitted well with both the Langmuir and Freundlich isotherms; the monolayer adsorption capacity (Q0 mg g−1) of the Delonix regia pods and leaves was 5.88 and 5.77 mg g−1 for Ni(II) ions respectively and 9.12 and 9.01 mg g−1 for Cu(II) ions respectively. The efficiency of the powdered pods and leaves of Delonix regia with respect to the removal of Ni(II) and Cu(II) ions was greater than 80 %, except for the sorption of Ni(II) ions onto the leaves. The desorption study revealed that the percentage of metal ions recovered from the pods was higher than that recovered from the leaves at various nitric acid concentrations. This study proves that Delonix regia biomass, an agricultural waste product (“agro-waste”), could be used to remove Ni(II) and Cu(II) ions from aqueous solution.

Highlights

Their persistent nature, non-biodegradability, toxicity and ability to bioaccumulate in the environment have made heavy metals priority pollutants (Hamza et al, 2013)
The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs of the Delonix regia pods and leaves (Fig. 1) indicated the spongy nature of Delonix regia, with the porous structures being potentially beneficial for the uptake of Ni(II) and Cu(II) ions from aqueous solution
The results obtained from this study show that Delonix regia biomass competes favourably with other agricultural waste that has been used in previous studies and, could be useful for removing Ni(II) and Cu(II) ions from aqueous solution

Summary

Introduction

Their persistent nature, non-biodegradability, toxicity and ability to bioaccumulate in the environment have made heavy metals priority pollutants (Hamza et al, 2013). Various health effects are caused by anthropogenic pollutants, which are mainly comprised of heavy metals such as mercury, nickel, lead, cadmium copper, zinc and cobalt, in water (Hamza et al, 2013; Singh et al, 2011). Copper is known to play a vital role in metabolism in animals, its excessive intake can result in serious health problems (Paulino et al, 2006). The permissible limit of copper in drinking water and wastewater is 0.5 and 2.5 mg L−1 respectively (Zhou et al, 2018; Kumar et al, 2019). Reactive free oxygen species that damage lipids, proteins and DNA are released when cop-

Objectives

Results

Conclusion