Characterization Analysis of Mudstone and Study of Its Pb (II) Adsorption Characteristics in Polluted Water Bodies

Zhang, Baoqiang; Zhao, Bo; Xia, Longfei; Sun, Yingying; Chen, Tianqing; Shi, Hailan

doi:https://doi.org/10.1155/2024/2510050

Journal of Chemistry

On this page

Abstract Introduction Materials and Methods Results and Discussion Conclusions Data Availability Conflicts of Interest Acknowledgments References Copyright Related Articles

Special Issue

Analysis and Remediation of Pollutants in Water and Soil

View this Special Issue

Research Article | Open Access

Volume 2024 | Article ID 2510050 | https://doi.org/10.1155/2024/2510050

Characterization Analysis of Mudstone and Study of Its Pb (II) Adsorption Characteristics in Polluted Water Bodies

Baoqiang Zhang,^1,2,3,4,5Bo Zhao,^1,2,3,4,5Longfei Xia,^1,2,3,4,5Yingying Sun,^1,2,3,4,5Tianqing Chen,^1,2,3,4,5and Hailan Shi^1,2,3,4,5

Academic Editor: Abhilash

Received03 May 2022

Revised31 Jul 2023

Accepted07 Mar 2024

Published25 Mar 2024

Abstract

In order to explore a medium material for the efficient treatment of Pb(II) pollutants in groundwater, in this paper, mudstone is selected as the medium material, and the morphological structure of the mudstone is characterizes via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analyses to study the feasibility of the mudstone adsorbing Pb(II) ions. Then, static adsorption experiments are carried out to investigate the removal effect of mudstone on Pb(II) in aqueous solutions under different conditions and to determine the optimal adsorption conditions. Finally, the results are fitted and analyzed using a thermodynamic model to explore the adsorption mechanism of the mudstone. The main results of this study are as follows. The main mineral composition of the mudstone used in the experiments includes CaCO₃, SiO₂, CaAl₂O₄·10H₂O, and CaFe₄O₇. The specific surface area of the mudstone is as high as 23.027 m²·g⁻¹, the pore size is 9.145 nm, and its surface structure is rough, with pores and fissures developed. The pore space and adsorption capacity of the mudstone were enhanced. When 1 g·L⁻¹ of mudstone was added, the pH value of the solution was 6, the reaction time was 60 min, and the initial concentration of Pb(II) was 30 mg·L⁻¹. The removal efficiency of Pb reached 84.5%, and the adsorption amount was 25.352 mg·g⁻¹. For the removal of Pb(II) from the aqueous solution by the mudstone under different concentrations of Pb(II), the reaction was in accordance with the Langmuir adsorption isotherm model, and the maximum adsorption amount reached 54.975 mg·g⁻¹. The relationship between the removal of Pb(II) and the reaction time was in accordance with the pseudo-second-order rate model. The results of this study suggest that mudstone can be used for the removal of Pb(II) from aqueous media.

1. Introduction

Water is an indispensable natural resource in human life and is an integral part of the ecological and environmental system [1]. Currently, due to the rapid development of agriculture and industry, the excessive use of chemical fertilizers and pesticides in the agricultural field has caused serious pollution of water bodies with Pb(II) ions [2, 3]. Pb(II) ions in water bodies are difficult to degrade, and they have a high toxicity. Long-term consumption of water with a high lead content is likely to cause cancer. The lead pollution cycle is long, and it is easily bioaccumulated. Through its gradual accumulation in the food chain, it causes serious harm to the human living environment, biosphere, and human health [4–7]. Therefore, the purification of polluted water bodies has become a research hotspot in the field of environmental science, and it is of great significance to apply clay mineral materials to the study of the adsorption of heavy metals in water bodies [8, 9]. There are two treatment methods for water bodies polluted by Pb(II) ions: one is to reduce the bioavailability of the Pb(II) ions in the water body, and the other is to directly remove the Pb(II) ions from the water body [10, 11]. Therefore, some efficient water treatment technologies, for example, physical adsorption, electrochemical adsorption, ion exchange, chemical precipitation, and a series of other treatment methods and technologies, are used in the treatment of Pb(II) in water bodies [12].

In the method of absorbing Pb(II), the choice of the adsorbent is extremely important. Clay minerals have a super-self-purification capacity in the restoration of water bodies polluted by Pb(II) ions [13]. The common clay minerals used to restore water bodies heavily polluted by Pb(II) ions include montmorillonite, attapulgite, zeolite, kaolinite, sepiolite, vermiculite, and illite [14–17]. As a mineral material with abundant reserves and a low price, mudstone is a composite clay mineral material composed of layered porous silicate-rich minerals. Mudstone is mainly composed of minerals such as illite, kaolinite, montmorillonite, quartz, feldspar, mica, epidote, chlorite, ferromanganese oxide, and organic matter [18]. There are certain differences in the mineral components contained in different regions [19]. Mudstone has a strong viscoelasticity, is easily weathered into fine particles, is easy to crush, easy to mine, cheap, and easy to obtain. In addition, as a composite clay mineral material, mudstone is a good soil-forming parent material, and its basic characteristics determine that it will not generate secondary pollution when used as an adsorbent. In addition, the restoration cost of this method is low, it is simple and easy to operate, and it has broad application prospects.

In this study, the adsorption method was used to remove the Pb(II) in a water body. The aim was to develop an environmentally friendly adsorption material with a high adsorption efficiency, good performance, and no secondary pollution. Therefore, in this study, through the characterization analysis of mudstone, the possibility of its adsorption of the heavy metal Pb(II) was explored, and the adsorption effect of the mudstone on Pb(II) in a water body under different influencing factors was investigated so as to provide a theoretical scientific basis and technical support for the efficient use of mudstone material.

2. Materials and Methods

2.1. Materials

The mudstone used in this study was collected from Yaoqu Village, Yaoqu Town, Yaozhou District, Tongchuan City, Shaanxi Province, and the chemical agent used was purchased from the Aladdin Reagent Co., Ltd. (Shanghai, China).

2.2. Preparation of Mudstone Material

First, the mudstone protolith collected was air dried, and the air-dried clay mineral material mudstone was refined. Then, the refined mudstone was cleaned with deionized water for three times to remove the impurities in the sample. The washed sample was air dried again and sieved through a 100-mesh screen to make the mudstone material required for the experiment. The prepared mudstone material was placed in a plastic bag and stored under dry conditions for later use. The basic physical and chemical properties of the mudstone material are presented in Table 1. The Pb content of the mudstone was far lower than the soil pollution risk screening value, and it did not carry the target heavy metal when adsorbing the Pb(II) in the polluted water body.

2.3. Characterization of Mudstone

The surface morphology and elements composition of the mudstone were analyzed using X-ray diffractometers (America -FEI-Quanta FEG 250 and Japan-Rigaku-Smart Lab 9KW models), and the specific surface area and pore size of the mudstone were determined using an America - Mack -ASAP 2020HD8.

2.4. Adsorption Experiment

A batch experiment was conducted to study the adsorption effect of the mudstone on Pb(II) in 100 mL of water contaminated with Pb(II) at a concentration of 30 mg·L⁻¹, Experiment 1: Different amounts of mudstone (0.25 g·L⁻¹, 0.5 g·L⁻¹, 0.75 g·L⁻¹, 1 g·L⁻¹, 1.25 g·L⁻¹, and 1.5 g·L⁻¹) were added to the contaminated water under constant temperature shaking. Experiment 2: The best adsorption amount of mudstone from experiment 1 was added to the polluted water, the pH of the solution was adjusted (2, 3, 4, 5, 6, 7, and 8), and the reaction time was 120 min. Adsorption experiments were conducted to determine the best pH value for heavy metal adsorption by the mudstone. Experiment 3: The best adsorption amount of mudstone from experiment 1 was added, and the pH was adjusted to the ideal value obtained from experiment 2. Then, experiments on Pb(II) adsorption by the mudstone were conducted to study the effect of the adsorption reaction time on the adsorption effect by collecting samples at different times (5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min); Experiment 4: Under the optimal conditions determined in Experiment 1, Experiment 2, and Experiment 3, mudstone was add to solutions with various initial Pb(II) concentration (10, 20, 30, 40, 50, and 60 mg·L⁻¹) to observe the Pb(II) adsorption effect of the mudstone under different initial concentrations. The supernatant of the adsorbed mixture was filtered, and the Pb(II) concentrations of the filtrate was determined via multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). To ensure the accuracy of the experiments, each experiment was repeated three times.

The removal rate and adsorption amount are important indicators of the performance of adsorbent materials. The adsorption amount and removal rate (R) of lead by the mudstone were calculated as follows:where is the unit adsorption capacity of the composite clay mineral material for Pb (II) after adsorption equilibrium (mg·L⁻¹); is the initial concentration of Pb(II) (mg·L⁻¹); is the concentration of Pb(II) in the adsorption equilibrium state (mg·L⁻¹); V is the volume of the sewage solution poured into the conical bottle initially (mL); m is the amount of mudstone used (g) [20].

3. Results and Discussion

3.1. Characterization Analysis of Mudstone

The scanning electron microscopy (SEM) morphology results for the mudstone are shown in Figures 1(a)–1(d). Figures 1(a)–1(d) present SEM photos of the mudstone collected from the Tongchuan area, Shaanxi, under magnifications of 5000x, 10000x, 20000x, and 50000x, respectively. It can be seen from Figure 1 that the surface structure of the mudstone is rough and consists of aggregates of irregular flakes; the particles are connected by irregular surface-to-surface and surface-to-edge contacts; and the pore channels of the mudstone are unobstructed. This scattered structure helps in the generation of pores, interstices, voids, cracks, fissures, and the connections between them. The pores, interstices, voids, cracks, and fissures are mostly formed via stacking of the irregular mineral particles contained in the mudstone, so there is a certain difference in the pore size and pore wall thickness. The size of the space between the pores also varies, which not only increases the free adsorption group of the mudstone but also helps the mudstone to form a pore channel structure. There are pores and fissure structures of different sizes distributed on the surfaces of the mudstone particles, which are aggregated in a disorderly manner. The well-developed pores and rough pore walls on the mudstone surface and the good connection between the pores enhance the effective space and adsorption capacity of the mudstone pore channels and improve the physical adsorption and chemisorption capacity of the mudstone.

Phase analysis of the mudstone material was carried out. The X-ray diffraction (XRD) results for the mudstone are shown in Figure 2. The results show that the minerals contained in mudstone mainly include CaCO₃, SiO₂, CaAl₂O₄•10H₂O, and CaFe₄O₇. This is because clay minerals are the main rock forming minerals in mudstone, and the clay minerals are mainly aluminum-silicate minerals. Therefore, the Si and Al contents of the mudstone are large. In addition, the shapes and positions of all of the main diffraction peaks of the mudstone are prominent, the XRD diffraction peaks of the crystals are sharp and symmetrical, and the crystal structure is complete. The strong binding capacity of the silicate minerals contained in the mudstone for Pb (II) can be used to improve the adsorption capacity of the mudstone for the heavy metal Pb (II) to a large extent.

Figure 3 shows the nitrogen adsorption curve of the mudstone. Based on analysis of the nitrogen adsorption curve, the adsorption isotherm belongs to the second category of the Brunauer-Emmett-Teller (BET) classification, with a small slope and slow rise in the first half and a sharp rise in the second half. As the relative pressure increases, capillary condensation occurs simultaneously with multilayer adsorption. When , the curve intersects with the ordinate (representing the adsorption volume) at a nonzero value, the intercepts are not equal, so there are micropores and the micropore volumes are not equal. The average specific surface area obtained using methods such as the BET method is 23.027 m²·g⁻¹, and the average pore size is 9.145 nm.

3.2. Adsorption of Pb(II) Ions in Batch Systems

The Pb(II) adsorption performance of the mudstone is not only related to its surface structure but is also influenced by external factors. Mudstone was used as the adsorption material to investigate the effects of the pH, amount of mudstone addition, reaction time, and initial Pb(II) concentration of solution on the heavy metal ion adsorption performance of the mudstone.

3.2.1. Effect of Mudstone Dosage on Absorption Effect

The results of the effect of the mudstone dosage on the removal of Pb(II) are shown in Figure 4. This is mainly due to the fact that the Pb(II) concentration of the solution was fixed, and the removal efficiency of Pb(II) increased gradually as the amount of mudstone increased, which caused the mudstone to reach adsorption equilibrium. The removal efficiency increased linearly as the amount of mudstone added increased from 0.25 g·L⁻¹ to 1 g·L⁻¹. The Pb(II) removal efficiency of the mudstone was as high as 85% when the amount of mudstone was 1 g·L⁻¹, and it had reached the equilibrium at this time. Although the Pb(II) adsorption efficiency of the mudstone exhibited a tendency toward equilibrium with increasing mudstone dosage, when the addition of mudstone was small, the specific surface area and the number of adsorption sites on the mudstone were limited, and the adsorption sites were fully utilized, thus reaching adsorption saturation quickly and resulting in a high adsorption amount. However, the limited number of adsorption sites was not sufficient to adsorb a large amount of the Pb(II) in the solution, so the removal efficiency was low [21]. As the addition of mudstone gradually increased, the specific surface area and the number of adsorption sites and functional groups of the mudstone also increased, which caused the Pb(II) content of the solution to decrease. However, this led to an excess of adsorption sites on the surface of the mudstone, and the phenomenon of unsaturated utilization of the adsorption sites occurred. Based on the analysis of the results presented in Figure 5, the optimum amount of mudstone addition was 1 g·L⁻¹ for Pb(II) adsorption by mudstone.

3.2.2. Effect of Solution pH on the Adsorption Effect

According to the above effect of the amount of mudstone addition on the Pb(II) adsorption effect of the mudstone, the amount of mudstone was set as 1 g·L⁻¹ in the experiment conducted to determine the effect of the solution pH on the adsorption effect. The removal efficiencies were all very low at pH < 3, and the removal efficiencies were significantly higher at pH = 3∼6. At pH = 6∼8, the curve leveled off and the removal efficiency stabilized near the maximum value, and the removal efficiency was above 85%. Therefore, mudstone is most suitable for Pb(II) removal under weakly acidic or neutral conditions. At pH 6-7, Pb(II) may combine with OH⁻ to produce Pb(OH)⁺ and Pb(OH)₂ complexes via precipitation, which reduces the unfavorable contact with the oxidized surface [22]. For pH 6-7, the increase in the removal of Pb(II) by the mudstone was the result of the combined effect of physical adsorption and a chemical precipitation reaction; the adsorption amount reached the maximum value, and the adsorption effect gradually stabilized [23]. The mudstone contained Fe and Al oxides with variable charges, and as the pH increased, the variable negative charge in the solution increased, causing the gravitational force on the Pb(II) increase and the electrostatic adsorption of Pb(II) increase. The pH of the solution not only affects the magnitude of the electricity charge on the surface of the clay mineral material and the activity of the adsorption sites, but also the form of the metal ions present in the solution, thus affecting its adsorption properties [24]. Therefore, pH = 6 was determined to be the optimum pH value for Pb(II) adsorption on mudstone.

3.2.3. Effect of Reaction Time on the Adsorption Effect

Based on the effects of the amount of mudstone addition and the pH of the solution on the adsorption effect, the optimum amount of mudstone addition and solution pH were set as 1 g·L⁻¹ and pH = 6, respectively, in the next set of adsorption experiments. As shown in Figure 6, the adsorption rate of Pb(II) by mudstone was fast, the Pb(II) concentration of the solution decreased rapidly, and the removal efficiency increased. The Pb(II) removal efficiency of the mudstone was nearly 75% in 0–20 min, and the adsorption capacity was nearly 23 mg·g⁻¹. At 60 min, the Pb(II) removal efficiency of the mudstone reached 89%, its Pb(II) adsorption capacity reached 26.7 mg·g⁻¹, and both the removal efficiency and adsorption capacity reached the maximum values. During the reaction, the removal efficiency and adsorption amount did not change significantly as the reaction time increased, and they reached an equilibrium state, indicating that the adsorption of Pb(II) by the mudstone was characterized by rapid adsorption and dynamic equilibrium, which is generally stable and will not be resolved [25]. In summary, in the experiment on the static adsorption of Pb(II) by mudstone, the adsorption time was set to 60 min. The rapid adsorption characteristics enable the mudstone to give full play to the adsorption performance in a short reaction time, which provides a new idea for solving the problem of the emergency treatment of water bodies polluted by heavy metal.

3.2.4. Effect of Pb(II) Ion Content on the Adsorption Effect

The experiments on the effect of different Pb(II) ion contents on the adsorption of Pb(II) were carried out using a mudstone addition of 1 g·L⁻¹, a solution pH of 6, and a reaction time of 90 min. Figure 7 shows the adsorption capacity and removal rate of the mudstone for different Pb(II) contents. It can be seen from Figure 7 that the Pb(II) adsorption capacity of the mudstone increased continuously as the Pb(II) ion content increased, while the removal efficiency exhibited a decreasing trend. On the one hand, the active sites and exchangeable ions on the surface of a certain mass of mudstone material are limited, and when the ionic strength increases to a certain degree, the adsorption sites and functional groups on the surface of the mudstone are reduced. On the other hand, the active sites and exchangeable ions on the surface of a certain mass of mudstone material are limited, and when the ionic strength increases to a certain level, the adsorption sites and functional groups on the surface of mudstone are fully utilized, and the material reaches adsorption saturation, resulting in the excess Pb(II) not being adsorbed, thus reducing the Pb(II) removal rate [26–28]. In addition, the Pb(II) removal efficiency of the mudstone was greater than 80% when the Pb(II) ion content was less than 30 mg·L⁻¹, and it gradually decreased when the Pb(II) ion content was between 30 mg·L⁻¹ and 50 mg·L⁻¹, but remained above 75%. Therefore, under the double consideration of the removal rate and adsorption capacity, the mudstone was more effective in removing Pb(II) ions from the solution with a lower Pb(II) ion content, but it also had some value in treating the solution with a high Pb(II) ion content [29, 30].

3.3. Adsorption Isotherm and Adsorption Kinetic Model Analysis

3.3.1. Analysis of the Adsorption Isotherm Model

The adsorption isotherm is the equilibrium state of the adsorption reaction when the reaction proceeds sufficiently at a specific temperature. When the adsorption reaction reaches equilibrium, there is a certain relationship between the ion concentration of the solution and the adsorption capacity of the adsorbent, and this dependence curve is the adsorption isotherm. It is possible to understand the trend of the isotherm under each parameter and to determine the strength of the adsorption performance. The equilibrium time is the time when the adsorption reaction reaches equilibrium, and the adsorption capacity corresponding to this time is the amount of equilibrium adsorption. The experimental results for the Pb(II) adsorption by mudstone from a solution were fitted using the following two models [31].(1)Langmuir adsorption isotherm model The adsorption model proposed by Langmuir in 1916 based on the theory of molecular motion is a commonly used equation for adsorption isotherms and has been widely used in the field of adsorption [32]. It is based on the assumption that the adsorption process is a dynamic process and that the desorption rate is the same as the adsorption rate when the adsorption reaction reaches equilibrium [33, 34]. It is applicable to adsorbents with a uniform volume distribution and when the adsorption reaction occurs between single molecular layers. The expression of its adsorption model equation is as follows [35]: Where b is the adsorption equilibrium constant; q_e is the adsorption amount at adsorption equilibrium (mg·g⁻¹); q_m is the theoretical saturation adsorption amount (mg·g⁻¹); and c_e is the equilibrium concentration of the liquid phase after adsorption equilibrium (mg·L⁻¹).(2)Freundlich adsorption isotherm model The Freundlich adsorption isotherm assumes that the adsorption process is a nonhomogeneous process, i.e., the adsorption sites on the surface of the adsorbent are irregular and are not independent of each other, but there may be a synergistic effect between the adsorption sites, and it belongs to an empirical equation that is applicable to multicomponent layer adsorption and surface adsorption under nonideal conditions [36]. The Freundlich adsorption isotherm can be used to express different systems of bilayers and reversible adsorption processes by fitting the following equation to the adsorption model [35]: Where k and n are the adsorption constants; q_e is the adsorption amount at adsorption equilibrium (mg·g⁻¹); and c_e is the equilibrium concentration of the liquid phase at adsorption reaction equilibrium (mg·L⁻¹).

Based on the results presented in Figures 8 and 9 and Table 2, both adsorption isotherm models can represent the adsorption process of the heavy metal Pb(II) by mudstone, but the correlation coefficient of the Langmuir isotherm model is higher(0.991), and it has a higher degree of linearity. This indicates that the Langmuir isotherm model is more suitable for the adsorption process of the heavy metal Pb(II) by mudstone. The correlation coefficient of the Freundlich adsorption isotherm model is 0.958 (i.e., >0.95), which indicates that the adsorption of the heavy metal Pb(II) by the mudstone occurred in a unimolecular layer structure, while the correlation coefficient of the Freundlich adsorption isotherm model is 0.958> (i.e., >0.95), which indicates that there is also a multimolecular layer reaction in the adsorption of the heavy metal Pb(II) by the mudstone [37]. The maximum adsorption capacity fitted using the Langmuir isotherm model was 54.975 mg·g⁻¹. The empirical constant derived from the Freundlich adsorption isotherm model is n = 1.771, 1 < 1.771 < 10, indicating that the adsorption reaction easily proceeds and that the reaction is difficult when n < 0.5 [38]. In summary, it can be concluded that the adsorption of the heavy metal Pb(II) by the mudstone is a relatively complex process, and single-molecular-layer adsorption and multimolecular-layer adsorption coexist and jointly affect the adsorption of the heavy metal Pb(II) by the mudstone.

3.3.2. Adsorption Kinetic Analysis

Adsorption kinetics is the study of the rate, time, and mechanism of adsorption and other characteristics of the reaction. The concentration of the adsorbent and the adsorbent mass can affect the rate of the adsorption reaction, and they are also closely related to the contact time. Usually, the analysis of adsorption kinetics is performed using the pseudo-primary kinetic model and the pseudo-secondary kinetic equation to fit the adsorption process of the studied ions and to predict the equilibrium adsorption capacity [39]. The expressions of the fitted equations are presented shown.

First-order equation [40]:

Secondary equation [41]:

In (4) and (5), is the pseudo-first-order adsorption equilibrium rate constant (min⁻¹), is the pseudo-second-order adsorption equilibrium rate constant (mg·(g min)⁻¹); is the equilibrium adsorption of lead by the mudstone at adsorption equilibrium (mg·g⁻¹); and is the adsorption of the heavy metal Pb(II) by the mudstone at time t (mg·g⁻¹).

Based on the results presented in Figures 10 and 11 and Table 3, we conclude that the adsorption reaction between the mudstone and the heavy metal Pb(II) has a relatively high degree of fitting for both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, but the value of the pseudo-second-order kinetic model is larger than that of the pseudo-first-order kinetic model, so the pseudo-second-order kinetic model is more consistent with the adsorption process of the heavy metal Pb(II) in a water body on mudstone. The theoretical adsorption capacity of 29.155 mg·g⁻¹ obtained from the fitted results is comparable to the adsorption capacity of 26.658 mg·g⁻¹ obtained from the experiments presented in the previous section, which further indicates that the pseudo-second-order kinetic model is more consistent with the adsorption of Pb(II) by the mudstone.

4. Conclusions

In this study, a mudstone composed of clay mineral material with abundant reserves in China was used as the research object, and the effects of the influencing factors, such as the amount of mudstone addition, solution pH, reaction time, and initial Pb(II) concentration of the solution, on the adsorption of Pb(II) from water bodies by a composite clay mineral material (mudstone) were investigated through static adsorption experiments. The main conclusions of this study are as follows.

The mechanism of using mudstone as a remediation material for lead-contaminated water was analyzed. The main clay minerals contained in the mudstone were CaCO₃, SiO₂, CaAl₂O₄·10H₂O, and CaFe₄O₇, among which the silicate minerals were dominant. Its surface structure was rough, and pores and fissures were developed. The clay minerals were abundant, and the cation exchange capacity, specific surface area, large pore size, and rich content of clay minerals indicate that using this mudstone to remediate lead-contaminated water using the adsorption mechanism is feasible. Regarding the factors affecting the adsorption of the Pb(II) in the solution by mudstone, the best Pb(II) adsorption effect of the mudstone in the static adsorption experiments was achieved when the amount of mudstone addition was 1 g·L⁻¹ and the pH was 6. The best Pb(II) adsorption effect of the mudstone was achieved under these conditions, and the removal efficiency can reached 85.5%. Regarding the adsorption reaction time, the Pb(II) removal efficiency of the mudstone was close to 75% at 30 min, and the Pb(II) adsorption capacity and removal rate of the mudstone were close to the highest value at 60 min, with a removal efficiency of close to 88.8%. After 60 min, the adsorption capacity and removal rate did not change significantly as the reaction time increased, and they tended to become stable. The initial Pb(II) concentration of the solution also affected the adsorption of Pb(II) by the mudstone. The higher the initial concentration was, the higher the adsorption capacity was, and the lower the removal efficiency was. The data obtained from the adsorption experiments on the adsorption of the heavy metal Pb(II) by the mudstone were linearly fitted, and it was concluded that the Langmuir isotherm model was more suitable for describing the adsorption of the heavy metal Pb(II) by the mudstone. In addition, the fitting results indicate that the adsorption of the heavy metal Pb(II) by the mudstone occurred in a single molecular layer structure; while the correlation coefficient of the Freundlich isotherm model was 0.958 (i,e.,> 0.95). This also indicates that the adsorption process of the heavy metal Pb(II) by the mudstone also involved a reaction in multimolecular layers. The R² value of the pseudo-secondary kinetic model is larger than that of the pseudo-first-order kinetic model, so the pseudo-secondary kinetic model is more consistent with the adsorption of the heavy metal Pb(II) by the mudstone. This also indicates that the adsorption of the heavy metal Pb(II) by the mudstone was dominated by chemisorption.

Data Availability

No data were used to support this study.

Conflicts of Interest

The authors declare that there are no conflicts of interest.

Acknowledgments

This project was funded by the internal scientific research project of Shaanxi Provincial Land Engineering and Construction Group and the Shaanxi Provincial Innovation Capacity Support Programme (funding numbers: DJNY2021-18 and 2021PT-053).

References

Y. Zhang, Research on Combined Adsorption Technology of Cadmium Ions in Sewage, Henan Normal University, Xinxiang, China, 2015.
C. Wang, Pollution Characteristics of Heavy Metal Contaminated Sediment in Xiawan Port and its Solidification and Stabilization Technology, Hunan University, Changsha, China, 2013.
S. X. Zhang, “Current status and evaluation of heavy metal pollution in water environment,” China Science and Technology Information, vol. 11, no. 13, pp. 32–36, 2009.
View at: Google Scholar
J. G. Xu, L. Wang, H. Y. Xiao, M. Gao, and J. Li, “Current status of heavy metal pollution in my country’s water environment and progress in detection technology,” Journal of Environmental Sciences, vol. 29, no. 5, pp. 104–108, 2010.
View at: Google Scholar
Y. N. Geng, “Research progress on heavy metal pollution in rivers,” Chinese Agricultural Science Bulletin, vol. 28, no. 11, pp. 262–265, 2012.
View at: Google Scholar
S. M. Wang, Y. H. Ma, Z. Liu, F. Han, J. P. Ma, and Q. Li, “Research progress on the characteristics of heavy metal pollution in urban precipitation,” South-to-North Water Transfers and Water Science & Technology, vol. 13, no. 2, pp. 279–283, 2015.
View at: Google Scholar
H. T. Huang, Y. P. Liang, C. C. Wei, H. Lin, and G. L. Mo, “Current status of water heavy metal pollution and its treatment technology,” Light Industry Science and Technology, vol. 25, no. 5, pp. 99-100, 2009.
View at: Google Scholar
P. X. Wu and Z. W. Liao, “Research progress of clay mineral strata,” Journal of Nature, vol. 22, no. 1, pp. 25–32, 2000.
View at: Google Scholar
J. R. Fu, A. J. Zhou, Y. Liu, Y. N. Wu, F. T. Li, and X. J. Wang, “Research progress of urban sewage reclamation technology in China,” Industrial water treatment, vol. 41, no. 1, pp. 18–24+37, 2021.
View at: Google Scholar
Y. Q. Yu and J. M. Cheng, “The 19th meeting of soil environment professional committee of Chinese soil society and the 2nd workshop on soil pollution prevention, control and remediation technology in shandong Province,” Workshop on Agricultural Soil Pollution and Remediation, 2017.
View at: Google Scholar
W. H. Zou, Study on the Adsorption of Copper and lead Ions by Manganese Oxide Modified Filter Materials, Hunan University, Changsha, China, 2006.
I. Ali, A. A. Basheer, X. Y. Mbianda et al., “Graphene based adsorbents for remediation of noxious pollutants from wastewater,” Environment International, vol. 127, pp. 160–180, 2019.
View at: Publisher Site | Google Scholar
G. Dobra, S. Garcia-Granda, A. Negre et al., “Silver adsorption on the low temperature activated AluminaGrades. I. Adsorption capacity and kinetics,” Revista de Chimie, vol. 73, no. 2, pp. 17–32, 2022.
View at: Publisher Site | Google Scholar
Y. Huang and N. Y. Gao, “Comparative study of fluoride removal performance of modified quartz sand and zeolite filter media,” Environmental Sanitation Engineering, vol. 3, pp. 128–131, 2003.
View at: Google Scholar
Y. Xu, X. F. Liang, L. Peng, Q. R. Zeng, and Y. M. Xu, “Research progress on the passivation remediation of heavy metal contaminated clay minerals in farmland soil,” Shandong Agricultural Sciences, vol. 49, no. 2, pp. 156–162+167, 2017.
View at: Google Scholar
G. J. Song, L. L. Yin, J. R. Wang, L. Wang, and C. H. Sun, “Advances in bentonite modification and its application in wastewater treatment,” Journal of Qingdao University Engineering&Technology Edition, vol. 4, pp. 35–39, 2004.
View at: Google Scholar
D. Xu, X. L. Tan, C. L. Chen, and X. K. Wang, “Removal of Pb(II) from aqueous solution by oxidized multiwalled carbon nanotubes,” Journal of Hazardous Materials, vol. 154, no. 1-3, pp. 407–416, 2008.
View at: Publisher Site | Google Scholar
R. Xiao, Study on the Passivation and Remediation Effect of Purple Mudstone on Cadmium Pollution of gray-brown Alluvial Paddy Soil, Sichuan Agricultural University, Ya'an, China, 2016.
J. B. Zhao, X. B. He, and T. J. Shao, “Material composition and microstructure of purple soils and purple mudstones in Chongqing area,” Acta Pedologica Sinica, vol. 49, no. 2, pp. 212–219, 2012.
View at: Google Scholar
W. X. Liu, J. L. Li, J. L. Wang, X. B. Chen, and X. Y. Meng, “Adsorption characteristics of modified paulownia leaf adsorbent for lead and cadmium in water,” Journal of Agro-Environment Science, vol. 33, no. 6, pp. 1226–1232, 2014.
View at: Google Scholar
K. Jayaram, I. Y. L. N. Murthy, H. Lalhruaitluanga, and M. N. V. Prasad, “Biosorption of lead from aqueous solution by seed powder of Strychnos potatorum L,” Colloids and Surfaces B: Biointerfaces, vol. 71, no. 2, pp. 248–254, 2009.
View at: Publisher Site | Google Scholar
W. Q. Ding, H. Li, X. L. Yang, and J. Y. Liao, “The effect of heavy metal adsorption on the surface charge properties of purple soil,” Journal of Agro-Environment Science, vol. 3, pp. 711–715, 2006.
View at: Google Scholar
K. Q. Li, Y. J. Wang, M. R. Yang, Z. Q. Zhu, and Z. Zheng, “Adsorption kinetics and mechanism of Pb(II) on polyamine functionalized mesoporous carbon,” Environmental Sciences, vol. 35, no. 8, pp. 3198–3205, 2014.
View at: Google Scholar
T. Zhang, L. C. Zheng, H. J. Yu et al., “Solution pH affects single, sequential and binary systems of sulfamethoxazole and cadmium adsorption by self-assembled cellulose: promotion or inhibition?” Journal of Hazardous Materials, vol. 402, Article ID 124084, 2021.
View at: Publisher Site | Google Scholar
J. Zhu, P. Wang, L. W. Luo, T. Y. Wang, and Y. Zhang, “Research status and progress of heavy metal ion adsorption by diatomaceous earth,” Journal of Central South University of Forestry and Technology, vol. 31, no. 7, pp. 183–189, 2011.
View at: Google Scholar
W. Liu, T. Wang, A. G. Borthwick et al., “Adsorption of Pb2+, Cd2+, Cu2+ and Cr3+ onto titanate nanotubes: competition and effect of inorganic ions,” Science of the Total Environment, vol. 456-457, pp. 171–180, 2013.
View at: Publisher Site | Google Scholar
D. P. Sounthararajah, P. Loganathan, J. Kandasamy, and S. Vigneswaran, “Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns,” Journal of Hazardous Materials, vol. 287, pp. 306–316, 2015.
View at: Publisher Site | Google Scholar
L. N. Nemeş and L. Bulgariu, “Optimization of process parameters for heavy metals biosorption onto mustard waste biomass,” Open Chemistry, vol. 14, no. 1, pp. 175–187, 2016.
View at: Publisher Site | Google Scholar
J. Y. Zhao, Study on the Adsorption Performance and Adsorption Mechanism of Honeycomb Stone for Heavy Metal Ions, Anhui Jianzhu University, Hefei, China, 2016.
T. R. Yu, G. L. Ji, and C. P. Ding, Electrochemistry of Variable Charge Soils, China Science press, Beijing, China, 1996.
Y. Wang, Preparation of Multi-Level Structures of Iron-Based Compounds and Their Application in the Field of Water Treatment and Lithium Power, Qingdao University of Science & Technoology, Shandong, China, 2014.
F. Gao, Screening of media Materials for the Treatment of Uranium Contaminants in Groundwater by PRB and its Effectiveness, East China University of Technology, Fuzhou, China, 2015.
M. J. Wu, Study on Adsorption Characteristics of High-Rank Apropelic Coal in Ankang Area, China University of Geosciences, Wuhan, China, 2012.
D. P. Wu, Coal Containing Methane Fluid-Solid Coupling Mathematical Model and its Application, Chongqing University, Chongqing, China, 2014.
U. Kumar and M. Bandyopadhyay, “Sorption of cadmium from aqueous solution using pretreated rice husk,” Bioresource Technology, vol. 97, no. 1, pp. 104–109, 2006.
View at: Publisher Site | Google Scholar
C. Shi, Study on the Removal of Rhodamine B from Water by Low Temperature Plasma with Activated Carbon Fiber, Hefei University of Technology, Hefei, China, 2013.
D. L. Guerra, C. Airoldi, V. P. Lemos, and R. S. Angélica, “Adsorptive, thermodynamic and kinetic performances of Al/Ti and Al/Zr-pillared clays from the Brazilian Amazon region for zinc cation removal,” Journal of Hazardous Materials, vol. 155, no. 1-2, pp. 230–242, 2008.
View at: Publisher Site | Google Scholar
Z. Wang, F. C. Yi, and Y. Feng, “Analysis of the adsorption behavior and mechanism of uranium on wood fiber,” Atomic Energy Science and Technology, vol. 49, no. 2, pp. 263–272, 2015.
View at: Google Scholar
M. K. Aroua, S. P. P. Leong, L. Y. Teo, C. Y. Yin, and W. M. A. W. Daud, “Real-time determination of kinetics of adsorption of lead(II) onto palm shell-based activated carbon using ion selective electrode,” Bioresource Technology, vol. 99, no. 13, pp. 5786–5792, 2008.
View at: Publisher Site | Google Scholar
S. Lagergren, “About the theory of so-called adsorption of soluble substances,” Kungl- Svenska Vetenskapsakademiens Handlingar, vol. 24, no. 4, pp. 1–39, 1898.
View at: Google Scholar
Y. S. Ho, “Review of second-order models for adsorption systems,” ChemInform, vol. 37, no. 48, pp. 681–689, 2006.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2024 Baoqiang Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

123

Downloads

84

Citations