Adsorption Isotherms and Kinetics of Lead and Cadmium Ions: Comparative Studies Using Modified Melon (Citrullus colocynthis) Husk

Francis James Ogbozige ,M Toko

doi:10.5829/ijee.2020.11.02.10

Francis James Ogbozige , M Toko

Open Access

https://doi.org/10.5829/ijee.2020.11.02.10

Copy DOI

Abstract

Growth in population has caused a corresponding increase in agricultural production which consequently led to an increase in agricultural wastes or byproducts. This is sometimes difficult to manage and may pose a menace to the society if not properly disposed. Hence, this research investigated the efficacy of utilizing agricultural byproduct (melon husk) in removing Pb2+ and Cd2+ from wastewaters so as to prevent their deleterious impact on ecosystem and public health. This was achieved by treating tannery effluents with melon husks modified with H3PO4, NaOH and CH4N2O. Results showed that, the Freundlich and Langmuir adsorption capacities on the modified melon husks ranged from 0.1403 – 1.551 mg/g and 0.1499 – 0.6013 mg/g, respectively. Also, the R2 values for Pseudo 1st and 2nd order rate constants ranged from 0.0272 – 0.2391 and 0.9112 – 0.9958, respectively. Hence, it was concluded that the modified melon husks followed Freundlich isotherm model as well as Pseudo-2nd order kinetics and could be effectively used to remove Pb2+ and Cd2+ from wastewater.

Highlights

The impact of heavy metals in wastewaters or effluents has long been identified by various researchers
The adsorption capacity and intensity (n) of the various adsorbent used were determined by plotting log qt against log ce for the various adsorbent applied
The rate constant (k1) of Pseudo-1st order kinetics for Pb2+ adsorbed by melon husk modified with phosphoric acid (H3PO4) is 0.0128 min-1

Summary

Introduction

The impact of heavy metals in wastewaters or effluents has long been identified by various researchers. Several conventional techniques of removing heavy metals from effluents have been developed in order to reduce or avoid its impacts. Citrullus colocynthis (Figure 1a) is highly demanding in West-African countries (developing countries) especially Nigeria since the seeds (Figure 1b) are used in preparing a special delicacy known as “egusi soup” after threshing. This encourage commercial cultivation of Citrullus colocynthis in the mentioned countries. It is important to investigate the efficacy of using the modified form of this abundant byproduct of Citrullus colocynthis, in adsorbing Pb2+ and Cd2+ in tannery effluents, which have been reported to have high concentrations of the said metals [3]

Methods

Results

Conclusion