Multi-analytical assessment of iron and steel slag characteristics to estimate the removal of metalloids from contaminated water

Abstract

A multi-analytical approach was used to develop a mathematical regression model to calculate the residual concentration of borate ions in water present at high initial content, as a function of the main physicochemical, mineralogical and electrokinetic characteristics after adsorption on five different types of iron and steel slag. The analytical techniques applied and slag properties obtained in this work were: X-ray Fluorescence for the identification of the main chemical compounds, X-ray Diffraction to determine crystalline phases, physical adsorption of nitrogen for the quantification of textural properties and zeta-potential for electrokinetic measurements of slag particles. Adsorption tests were carried out using the bottle-point technique and a highly concentrated borate solution (700 mg B/L) at pH 10, with a slag dose of 10 g/L. An excellent correlation between the residual concentration of boron and three independent variables (content of magnesium oxide, zeta potential and specific surface area) was established for the five types of slag tested in this work. This shows that the methodology based on a multi-analytical approach is a very strong and useful tool to estimate the performance of iron and steel slag as adsorbent of metalloids.

Keywords:

• Adsorption
• crystal structure
• model
• morphology
• zeta potential.

Acknowledgments

B. M. Mercado-Borrayo gratefully acknowledges the financial support through the PhD Scholarship from “Coordinación de Estudios de Posgrado,” Universidad Nacional Autónoma de México (CEP, UNAM). The authors also acknowledge the financial support from DGAPA, UNAM (IT114511) to carry out this research project. The authors would like to thank Manuel Aguilar Franco (Instituto de Física, Universidad Nacional Autónoma de México) for the X-Ray Diffraction facilities.