Removal of Cd(II), Cu(II), and Pb(II) by adsorption onto natural clay: a kinetic and thermodynamic study

Abstract

IntroductionNatural water resources are becoming increasingly scarce. Thus, the state of the environment has become one of humanity's major concerns because of its degradation. This degradation is mainly due to industrial development which generates effluents discharged into the receiving environment without any treatment in most cases. These releases consist of toxic chemical elements and compounds, including heavy metals, which pose a serious threat to our environment and impair water quality. Currently, they are of great concern because of their toxicity to ecosystems and their harmful effects on human health. Cadmium, copper, and lead are considered to be dangerous micropollutants [1], the toxicity caused by these metals is considered to be high even to the state of traces [2]. Many cleaning methods and techniques have been developed in recent years to remove heavy metals from polluted waters. These techniques include chemical precipitation processes, flocculation, filtration, ion exchange, membrane processes, and adsorption [3][4][5][6][7][8]. The most used and studied method is adsorption method, due to its ease of use and the high availability and abundance of natural adsorbents [9][10][11][12]. Activated carbons are among the most widely used materials due to their high adsorption capacity [13], but they have numerous disadvantages, including high cost, intraparticle resistance in the adsorption process, low mechanical strength, and difficulty to regenerate. [14].Natural clay minerals have recently received considerable attention as alternative materials that are less expensive, nontoxic, and abundant and that have multifunctional properties depending on the type of clay [15]. The main advantages of using these materials are due to their different characteristics, low cost, and abundant availability.The aim of this study is the valorization of a Moroccan natural clay as an adsorbent for the removal of cadmium, copper, and lead from synthetic aqueous solutions. The adsorbent was characterized using the X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) methods. To better understand the nature

Modification of silica nanoparticles by 2,4-dihydroxybenzaldehyde and 5-bromosalicylaldehyde as new nanocomposites for efficient removal and preconcentration of Cu(ii) and Cd(ii) ions from water, blood, and fish muscles

“…A comparison study was made between the adsorption capacity of the synthesized nanocomposites and that of other adsorbents such as biochar, FAUtype zeolite, thio-functionalized layered double hydroxide, sulfhydryl functionalized hydrogel, and silica/dibenzoylmethane composite as shown in Table 6. [28][29][30][31][32][38][39][40][41] Clearly, the N 1 and N 2 nanocomposites outperformed the majority of adsorbents because they possess a high adsorption capacity. number in the case of Cu(II) and Cd(II) ions, respectively.…”

Formulation of Novel Composite (Activated Nanoclay/Hydrocolloid of Nostoc sphaericum) and Its Application in the Removal of Heavy Metals from Wastewater

“…The pseudo first-order model showed values of R 2 > 0.944, and the pseudo second-order model reported R 2 > 0.980 ( Table 4 ). The fact that the fit of the pseudo first-order model is slightly lower could be attributed to the limitations of the boundary layers that control the physical adsorption processes [ 21 , 22 ]. Therefore, the adsorption of metals would be subject to chemisorption processes, which allows a better description of the pseudo second-order model [ 16 , 23 ].…”

“…On the other hand, the use of inert materials with a high affinity for heavy metals in aqueous solution are widely used in wastewater treatment, with clays standing out among them, due to their high adsorption and ion exchange capacity, low permeability, swelling capacity, chemical, and physical stability and high surface area [ 18 , 19 , 20 ]. This allows ionic and covalent bonds to be established between the metal cations and the surface functional groups of the clays [ 21 , 22 ].…”

Kinetic and thermodynamic study on adsorption of cadmium from aqueous solutions using natural clay

“…Recently clay minerals have received considerable attention as alternative adsorbent materials that are less expensive, abundant and have multifunctional properties depending on the type of clay (17). The main advantages of using these materials are due to their different characteristics, abundant availability, and low cost (18). This work aims to enhance Moroccan natural clay's value in the retention of cadmium ions from synthetic aqueous solutions.…”

“…The loss on ignition (LoI) equal to 5.77% by mass. It is due to the decomposition of carbonates and dehydroxylation of clay minerals (18,22).…”