1. Introduction
Toxic heavy metals discharged of industrial wastewater are considered as a serious environmental problem since they exhibit a significant health threat to aquatic communities. Several methods have been used to clean up the environment from these kinds of contaminants, but most of them are costly and far away from their optimum performance. Great efforts have been exerted to test natural low cost adsorbents for metal ion removal [1], [2], [3], [4], [5] and [6]. For instance, plants were used in the wastewater treatment [7]. During the last two decades, there has been a growing interest in the use of water hyacinth plant in treating polluted effluents as an effective phytoremediation tool [8], [9], [10], [11] and [12]. This plant is aquatic and growing abundantly in Egypt as well as in tropical and sub-tropical regions of the world. It can remove both organic as well as inorganic pollution [13]. Further, its dried form has the ability to mediate heavy metals effectively without consuming water from the surrounding environment [14]. It is effectively applied as bio-sorbent for the removal of Cd (II) and Pb (II) from aqueous solution [15]. The mechanism by which the plant interacts with metal oxides (organo–metallic interaction) is described by molecular modeling and verified experimentally by Fourier transform infrared spectroscopy [13] and [16]. Both FTIR and modeling have demonstrated that the water hyacinth plant is cellulose like material [17]. Later on, examination indicated that the water hyacinth is composed of cellulose, lignin and some metal oxides [18]. Although dielectric spectroscopy has been applied successfully to investigate pollution for many kinds of plants [19], [20], [21], [22] and [23], its application to water hyacinth plant has been limited [24] and [25]. Therefore, studying the dynamic molecular behavior by means of dielectric spectroscopy may give us meaningful information about the plant–metallic interaction mechanism. Dielectric spectroscopy over a wide range of frequency at room temperature was applied to the dried plant before and after subjecting to different microwave heating powers for different times. Further, the dielectric modulus spectra M″ (ω) were fitted by a special computer program using the three-term Havriliak–Negami (HN) model [26] in order to define the possible relaxation processes taking place in the plant and also to investigate how these processes are affected by pollutants (heavy metals and metal oxides), concentrations and types.
1. บทนำToxic heavy metals discharged of industrial wastewater are considered as a serious environmental problem since they exhibit a significant health threat to aquatic communities. Several methods have been used to clean up the environment from these kinds of contaminants, but most of them are costly and far away from their optimum performance. Great efforts have been exerted to test natural low cost adsorbents for metal ion removal [1], [2], [3], [4], [5] and [6]. For instance, plants were used in the wastewater treatment [7]. During the last two decades, there has been a growing interest in the use of water hyacinth plant in treating polluted effluents as an effective phytoremediation tool [8], [9], [10], [11] and [12]. This plant is aquatic and growing abundantly in Egypt as well as in tropical and sub-tropical regions of the world. It can remove both organic as well as inorganic pollution [13]. Further, its dried form has the ability to mediate heavy metals effectively without consuming water from the surrounding environment [14]. It is effectively applied as bio-sorbent for the removal of Cd (II) and Pb (II) from aqueous solution [15]. The mechanism by which the plant interacts with metal oxides (organo–metallic interaction) is described by molecular modeling and verified experimentally by Fourier transform infrared spectroscopy [13] and [16]. Both FTIR and modeling have demonstrated that the water hyacinth plant is cellulose like material [17]. Later on, examination indicated that the water hyacinth is composed of cellulose, lignin and some metal oxides [18]. Although dielectric spectroscopy has been applied successfully to investigate pollution for many kinds of plants [19], [20], [21], [22] and [23], its application to water hyacinth plant has been limited [24] and [25]. Therefore, studying the dynamic molecular behavior by means of dielectric spectroscopy may give us meaningful information about the plant–metallic interaction mechanism. Dielectric spectroscopy over a wide range of frequency at room temperature was applied to the dried plant before and after subjecting to different microwave heating powers for different times. Further, the dielectric modulus spectra M″ (ω) were fitted by a special computer program using the three-term Havriliak–Negami (HN) model [26] in order to define the possible relaxation processes taking place in the plant and also to investigate how these processes are affected by pollutants (heavy metals and metal oxides), concentrations and types.
การแปล กรุณารอสักครู่..