Biosorption of Co2+ Ions from Aqueous Solution by K2HPO4-Pretreated Duckweed Lemna gibba

Jessica Lizeth Reyes-Ledezma,Liliana Morales-Barrera,Eliseo Cristiani-Urbina

doi:10.3390/pr8121532

Abstract

The wastewater of the many industries that use divalent cobalt (Co2+)-containing compounds has elevated levels of this metal. Thus, novel technology is needed to efficiently remove Co2+ ions from aqueous solutions. Biosorption is a low-cost technique capable of removing heavy metals from contaminated water. This study aims to evaluate the performance of KH2PO4-pretreated Lemna gibba (PLEM) as a biosorbent of Co2+ in aqueous solutions tested under different conditions of pH, particle size, and initial Co2+ concentration. Kinetic, equilibrium, and thermodynamic studies were conducted. The capacity of biosorption increased with a greater initial Co2+ concentration and was optimal at pH 7.0 and with small-sized biosorbent particles (0.3–0.8 mm). The pseudo-second-order sorption model best describes the experimental data on Co2+ biosorption kinetics. The Sips and Redlich-Peterson isotherm models best predict the biosorption capacity at equilibrium. According to the thermodynamic study, biosorption of Co2+ was endothermic and spontaneous. The effect of pH on the biosorption/desorption of Co2+ suggests that electrostatic attraction is the main biosorption mechanism. SEM-EDX verified the presence of Co2+ on the surface of the pretreated-saturated biosorbent and the absence of the metal after desorption.

Highlights

IntroductionUrbanization, and industrial development have increased the pollution of the planet and altered ecosystems
Excessive population growth, urbanization, and industrial development have increased the pollution of the planet and altered ecosystems
The level of pH is one of the physicochemical factors that most influence the biosorption of heavy metals [25]

Summary

Introduction

Urbanization, and industrial development have increased the pollution of the planet and altered ecosystems. The main source of water pollution is the discharge of industrial wastewater with diverse toxic substances, among which heavy metals are of particular concern [1]. Cobalt is a heavy metal found in the Earth’s crust, being a natural component of volcanic emissions, as well as surface and subterranean water. It is released into the environment through anthropogenic activities: Burning fossil fuels, applying fertilizers, mining, electroplating, manufacturing batteries, and producing commodities with industrial processes involving cobalt-containing compounds, among others. It can give rise to skin irritation and problems in bone development, as well as respiratory, cardiac, thyroid, liver, and gastric disorders [4,5]

Objectives

Methods

Results

Conclusion