Adsorption of Lead Ions from Aqueous Solutions Using Gamma Irradiated Minerals

Julián Cruz-Olivares,Carlos Eduardo Barrera-Díaz,César Pérez-Alonso,María Del Carmen Chaparro-Mercado,Fernando Ureña-Núñez,Gonzalo Martínez-Barrera

doi:10.1155/2016/8782469

Abstract

For the first time, an irradiated mineral was used as a novel modified adsorbent for lead removal of aqueous solutions. The effects of gamma radiation doses and temperature on the lead adsorption capacity of an unknown mineral were evaluated. The results show that, in the chemisorption process, the highest adsorption capacity (9.91 mg/g) and the maximum percentage of lead removal (99.1%) were reached at 40°C when using an irradiated mineral at 150 kGy. The improvement on the lead adsorption speed was the most important feature of the irradiated mineral. The experimental results were successfully correlated with the pseudo second-order kinetic model. For all results, the average absolute relative deviations (AARD) were less than 13.20%, and the correlation factor (r2) was higher than 0.998. Moreover, the average values of the thermodynamic parameters (ΔG0=-10612 J/mol, ΔH0=-12360 J/mol, and ΔS0=171 J/mol K) suggest the feasibility of the proposed process, in terms of the endothermic and irreversible chemisorption results; moreover, ion exchange was evaluated through the EDS results. The X-ray diffraction analysis showed that the unknown irradiated mineral is mainly composed of quartz (SiO2), calcite (CaCO3), and calcium magnesium silicate (Ca0.15Mg0.85) Mg (SiO6).

Highlights

Despite the strict regulations on environmental issues imposed in many countries [1, 2], today, it is still possible to find some heavy metal ions in the wastewater because of industrial processes
Aqueous solutions with 100 mg/L lead concentration were prepared by dissolving dried salt (159.8 mg) of lead nitrate [Pb(NO3)2] in distilled water (1 L)
The average absolute relative deviations (AARD) were lower than 13.20%, and the correlation factor (r2) was higher than 0.998

Summary

Introduction

Despite the strict regulations on environmental issues imposed in many countries [1, 2], today, it is still possible to find some heavy metal ions in the wastewater because of industrial processes. Aquatic animals and plants and the human health is at risk [3,4,5]. Lead is one of the most dangerous metals for the human health, especially for children because their growing bodies can absorb a higher quantity than adults [6,7,8]. At low concentrations of lead ions in the blood, some not dangerous diseases such as anemia, diarrhea, and headaches are observed, but, at a higher concentration (>10 μg/L), the liver, kidney, and neurological and reproductive systems can be severely affected [11, 12]

Methods

Results

Conclusion