V
Volume
WHO
World Health Organization
XRD
X-ray diffraction
λ
The applied X-ray wavelength
θ
The angle between the incident beam and the scattering plane(s)
1 Introduction
Contamination of air, water, and soil by heavy metals is a pressing global issue that
poses huge threats to the environment and public health, due to long- and short-term
toxicological effects [1–3]. Cadmium (Cd) is a heavy metal that is commonly found
in zinc/lead mining waste, alkaline batteries, electroplating products, PVC stabilizers, semiconductors, and solar cells [4, 5]. The release of Cd-containing pollutants
from solid waste into the environment causes serious contamination [2, 6, 7]. Cadmium accumulates in food chains and is easily absorbed by the human body, where it
exerts toxic effects on health and results in a great number of acute and chronic
diseases (including kidney failure, skeletal deformation, and lung cancer) [6]. In an
attempt to eliminate Cd pollution in solid waste and from combustion processes,
many techniques (such as solidification/stabilization by cement or sorption by
minerals) have been developed [4, 8–12]. However, most of them have many
inconvenient drawbacks, such as their low treatment efficiency, consumption of
large amounts of raw materials, and formation of undesired products [10, 13, 14].
Recently, a technology inspired by ceramic sintering processes has proved to be
effective and reliable for the stabilization of heavy metals (including Ni, Zn, Cu, and
Pb) [15–19]. The interactions of metal-containing waste with a series of inexpensive
and easily attainable ceramic matrices have been explored, and various stable
ceramic (crystalline) products with high acid resistance have been formed. This
novel technique has suggested a possible method for the stabilization of
Cd-containing waste. In addition, studies have demonstrated that cadmium oxide
(CdO) can thermally react with certain metal oxides (such as Al 2 O 3 , SiO 2 , and
Fe 2 O 3 ) or Al/Si-rich materials (e.g., kaolinite and mullite) [20–25]. With thermal
treatment, a number of robust crystalline products with particular crystal structures
can be harvested. Thermally treating CdO with these ceramic matrices suggests
further possible and feasible techniques for Cd incorporation. However, the
processing parameters and mechanisms of Cd incorporation should be determined
by thorough investigation.
This chapter addresses the sources and toxicity of Cd, methods of Cd detoxification, and techniques to evaluate the Cd stabilization effects. The feasibility of using
various Al/Fe/Si-based ceramic matrices to detoxify Cd in wastes via a sintering
process is investigated. The detoxification and stabilization of Cd can be achieved by
transforming it into crystalline products. The influences of operational parameters
(i.e., sintering temperature and the molar ratios of reactants) are considered in detail.
7 Advances in Cadmium Detoxification/Stabilization by Sintering with Ceramic. . .
301
Volume
WHO
World Health Organization
XRD
X-ray diffraction
λ
The applied X-ray wavelength
θ
The angle between the incident beam and the scattering plane(s)
1 Introduction
Contamination of air, water, and soil by heavy metals is a pressing global issue that
poses huge threats to the environment and public health, due to long- and short-term
toxicological effects [1–3]. Cadmium (Cd) is a heavy metal that is commonly found
in zinc/lead mining waste, alkaline batteries, electroplating products, PVC stabilizers, semiconductors, and solar cells [4, 5]. The release of Cd-containing pollutants
from solid waste into the environment causes serious contamination [2, 6, 7]. Cadmium accumulates in food chains and is easily absorbed by the human body, where it
exerts toxic effects on health and results in a great number of acute and chronic
diseases (including kidney failure, skeletal deformation, and lung cancer) [6]. In an
attempt to eliminate Cd pollution in solid waste and from combustion processes,
many techniques (such as solidification/stabilization by cement or sorption by
minerals) have been developed [4, 8–12]. However, most of them have many
inconvenient drawbacks, such as their low treatment efficiency, consumption of
large amounts of raw materials, and formation of undesired products [10, 13, 14].
Recently, a technology inspired by ceramic sintering processes has proved to be
effective and reliable for the stabilization of heavy metals (including Ni, Zn, Cu, and
Pb) [15–19]. The interactions of metal-containing waste with a series of inexpensive
and easily attainable ceramic matrices have been explored, and various stable
ceramic (crystalline) products with high acid resistance have been formed. This
novel technique has suggested a possible method for the stabilization of
Cd-containing waste. In addition, studies have demonstrated that cadmium oxide
(CdO) can thermally react with certain metal oxides (such as Al 2 O 3 , SiO 2 , and
Fe 2 O 3 ) or Al/Si-rich materials (e.g., kaolinite and mullite) [20–25]. With thermal
treatment, a number of robust crystalline products with particular crystal structures
can be harvested. Thermally treating CdO with these ceramic matrices suggests
further possible and feasible techniques for Cd incorporation. However, the
processing parameters and mechanisms of Cd incorporation should be determined
by thorough investigation.
This chapter addresses the sources and toxicity of Cd, methods of Cd detoxification, and techniques to evaluate the Cd stabilization effects. The feasibility of using
various Al/Fe/Si-based ceramic matrices to detoxify Cd in wastes via a sintering
process is investigated. The detoxification and stabilization of Cd can be achieved by
transforming it into crystalline products. The influences of operational parameters
(i.e., sintering temperature and the molar ratios of reactants) are considered in detail.
7 Advances in Cadmium Detoxification/Stabilization by Sintering with Ceramic. . .
301