The synergistic adsorption of pyrene and copper onto Fe(III) functionalized mesoporous silica from aqueous solution

Co-toxicity and co-contamination remediation of polycyclic aromatic hydrocarbons and heavy metals: Research progress and future perspectives

The combined pollution of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) has attracted wide attention due to their high toxicity, mutagenicity, carcinogenicity and teratogenicity. A thorough understanding of the progress of the relevant studies about their co-toxicity and co-contamination remediation is of great importance to prevent environmental risk and develop new efficient remediation methods. This paper summarized the factors resulting in different co-toxic effects, the interaction mechanism influencing co-toxicity and the development of remediation technologies for the co-contamination. Also, the inadequacies of the previous studies related to the co-toxic effect and the remediation methods were pointed out, while the corresponding solutions were proposed. The specific type and concentration of PAHs and HMs, the specific type of their action object and environmental factors could affect their co-toxicity by influencing each other's transmembrane process, detoxification process and increasing reactive oxygen species (ROS) and some other mechanisms that need to be further studied. The specific action mechanisms of the concentration, environmental factors and the specific type of PAHs and HMs, their effect on each other's transmembrane processes, investigations at the cellular and molecular levels, non-targeted metabolomics analysis, as well as long-term ecological effects were proposed to be further explored in order to obtain more information about the co-toxicity. The combination of two or more methods, especially combining bioremediation with other methods, is a potential development field for the remediation of co-contamination. It can make full use of the advantages of each remediation method, to achieve an increase of remediation efficiency and a decrease of both remediation cost and ecological risk. This review intends to further improve the understanding on co-toxicity and provide references for the development and innovation of remediation technologies for the co-contamination of PAHs and HMs.

Investigation the existence and mechanism of Cu(II)-sulfamethoxazole co-pollution by road-deposited sediments in stormwater runoff

In recent years, the escalating attention on Pharmaceutical and Personal Care Products (PPCPs) and Heavy Metals in urban stormwater runoff highlights the critical role of Road-deposited sediments (RDS) as a significant carrier for pollutant occurrence and transport in runoff. However, existing research has overlooked the composite characteristics of PPCPs and Heavy Metals, hampering a holistic understanding of their transformation in diverse forms within runoff. This limitation impedes the exploration of their subsequent migration and conversion properties, thereby obstructing coordinated strategies for the control of co-pollution in runoff. This study focuses on the typical PPCP sulfamethoxazole (SMX) and heavy metal Cu(II) to analyze their occurrence characteristics in the Runoff-RDS system. Kinetics and isotherm studies reveal that RDS effectively accumulates SMX and Cu(II), with both exhibiting rapid association with RDS in the early stages of runoff. The accumulation of SMX and Cu(II) accounts for over 80 % and 70 % of the total accumulation within the first 240 min and 60 min, respectively. Moreover, as runoff pH values decrease, the initially synergistic effect between the co-pollutant transforms into an antagonistic effect. In the composite system, varying pH values from 2.0 to 6.0 lead to an increase in SMX accumulation from 4.01 mg/kg to 6.19 mg/kg and Cu(II) accumulation from 0.43 mg/g to 3.39 mg/g. Compared to the single system, the composite system capacity for SMX and Cu(II) increases by 0.04 mg/kg and 0.33 mg/g at pH 4.0. However, at pH 3.0, the composite system capacity for SMX and Cu(II) decreases by 0.21 mg/kg and 0.36 mg/g, respectively. Protonation/deprotonation of SMX under different pH conditions influences electrostatic repulsion/attraction between SMX and RDS. The mechanism of RDS accumulation of SMX involves Electron Donor-Acceptor (EDA) interaction, hydrogen bond interaction, and Lewis acid-base interaction. Cu(II) enrichment on RDS includes surface complexation reaction, electrostatic interaction, and surface precipitation. Complex formation enhances the accumulation of both SMX and Cu(II) on RDS in runoff. This study elucidates the co-occurrence characteristics and mechanisms of SMX and Cu(II) co-pollution in runoff systems. The findings contribute valuable insights to understanding the existence patterns and mechanisms of co-pollution, providing a reference for investigating the migration and fate of co-pollutant in runoff. Moreover, these insights could offer guidance for the development of effective strategies to mitigate co-pollution in rainwater.

Adsorption of Pyrene and Arsenite by Micro/Nano Carbon Black and Iron Oxide

Polycyclic aromatic hydrocarbons (PAHs) and arsenic (As) are common pollutants co-existing in the environment, causing potential hazards to the ecosystem and human health. How their behaviors are affected by micro/nano particles in the environment are still not very clear. Through a series of static adsorption experiments, this study investigated the adsorption of pyrene and arsenite (As (III)) using micro/nano carbon black and iron oxide under different conditions. The objectives were to determine the kinetics and isotherms of the adsorption of pyrene and As (III) using micro/nano carbon black and iron oxide and evaluate the impact of co-existing conditions on the adsorption. The microstructure of micro/nano carbon black (C 94.03%) is spherical-like, with a diameter of 100-200 nm. The micro/nano iron oxide (hematite) has irregular rod-shaped structures, mostly about 1 µm long and 100-200 nm wide. The results show that the micro/nano black carbon easily adsorbed the pyrene, with a pseudo-second-order rate constant of 0.016 mg/(g·h) and an adsorption capacity of 283.23 μg/g at 24 h. The micro/nano iron oxide easily adsorbed As (III), with a pseudo-second-order rate constant of 0.814 mg/(g·h) and an adsorption capacity of 3.45 mg/g at 24 h. The mechanisms of adsorption were mainly chemical reactions. Micro/nano carbon black hardly adsorbed As (III), but its adsorption capability for pyrene was reduced by the presence of As (III), and this effect increased with an increase in the As (III) concentration. The adsorbed pyrene on the micro/nano black carbon could hardly be desorbed. On the other hand, the micro/nano iron oxide could hardly adsorb the pyrene, but its adsorption capability for As (III) was increased by the presence of pyrene, and this effect increased with an increase in the pyrene concentration. The results of this study provide guidance for the risk management and remediation of the environment when there is combined pollution of PAHs and As.

Enhanced Cr (VI) reduction and removal by Fe/Mn oxide biochar composites under acidic simulated wastewater

Chromium (Cr (VI)) can cause severe damage to the ecosystem and humans because of its toxicity. In this paper, the adsorbed Fe/Mn ions Bacillus cereus ZNT-03, lotus seeds, and graphene oxide were co-cultured as the raw materials. Fe/Mn oxide biochar composite (FMBC) was prepared to treat Cr (VI) by one-step pyrolysis. FMBC has high-density micropores, and the average pore size is about 0.82 nm. Fe (II), Mn (II), and N-containing functional groups could serve as electron donors for Cr (VI) reduction. The removal of Cr (VI) is monolayer chemisorption and pH-dependent. The maximum adsorption capacity of FMBC is 21.25 mg g^-1. Cr (VI) is reduced and adsorbed on FMBC by physical adsorption, reduction, complexation, electrostatic attraction, and coprecipitation. The contribution ratio of the reduction mechanism to Cr (VI) is 72.25%. The packed column and regeneration experiments indicated that FMBC had excellent adsorption stability even after soaking in acidic simulated wastewater after 180 days (pH 1.5). These results indicate that FMBC can provide rapid reduction and efficient adsorption for Cr (VI), making it possible to apply in water treatment.

Research Progress on Adsorption and Separation of Petroleum Hydrocarbon Molecules by Porous Materials

Petroleum is an indispensable chemical product in industrial production and daily life. The hydrocarbon molecules in petroleum are important raw materials in the organic chemical industry. The hydrocarbons currently used in industry are usually obtained by fractional distillation of petroleum, which not only consumes more energy, but has poor separation selectivity for some hydrocarbons. Adsorption separation technology has many advantages such as energy saving and high efficiency. It can adsorb and separate hydrocarbon molecules in petroleum with low energy consumption and high selectivity under mild conditions. In this paper, the research progress of adsorption and separation of hydrocarbon molecules in petroleum is reviewed, and various new catalysts and the rules of adsorption and desorption are analyzed.

Effect of γ-Fe2O3 nanoparticles on the composition of montmorillonite and its sorption capacity for pyrene

Fe content and distribution on montmorillonite would probably enhance its sorption capacity for hydrophobic organic pollutants. Thus, Fe modified montmorillonites with different ratios of FeSO₄·7H₂O and Ca-montmorillonite were prepared. The results indicated that γ-Fe₂O₃ nanoparticles were not only generated at the montmorillonite surfaces, but that the γ-Fe₂O₃ also extended the edges of montmorillonite surfaces. The sorption capacities for pyrene were enhanced and even reached 834.79 μg g^-1 with increase in ferrous iron content, but were then suppressed due to aggregation of γ-Fe₂O₃ on montmorillonite surfaces. Furthermore, pyrene was directly observed on γ-Fe₂O₃-montmorillonite surfaces with a lattice spacing parameter of approximately 0.27 nm, indicating that a new phase that mainly contained pyrene was generated during the sorption process. Additionally, after regenerating the γ-Fe₂O₃-montmorillonite composites, they could be reused for at least 5 cycles. It is therefore proposed that the prepared γ-Fe₂O₃-montmorillonite could be exploited as a potential green composite for remediation of hydrophobic organic pollutants in soil and sediment.

High-efficiency adsorption of phenanthrene by Fe3O4-SiO2-dimethoxydiphenylsilane nanocomposite: Experimental and theoretical study

Phenanthrene (PHE), as one of representative polycyclic aromatic hydrocarbons (PAHs) can cause serious adverse effects on human health, developing effective adsorbents to alleviate PHE contamination is in urgent demand. A novel Fe₃O₄-SiO₂-Dimethoxydiphenylsilane (Fe₃O₄-SiO₂-2DMDPS) nanocomposite was fabricated from encapsulation and grafting process. Magnetic Fe₃O₄ nanoparticles were served as preliminary matrix material, SiO₂ was used to link the magnetic oxide and provide hydroxyl groups for proceeding the silane coupling reaction subsequently, and the aromatic rings in DMDPS could provide active sites for PHE adsorption via π-π interaction. SEM-EDS, TEM, BET, VSM, XRD, FTIR, Raman, Zeta potential, and XPS techniques were used to characterize magnetic nanocomposite. The prepared Fe₃O₄-SiO₂-2DMDPS exhibited an excellent adsorption performance towards PHE, it could maintain 75.97% adsorption capacity after four regeneration cycles. Homogeneous adsorption acted crucial role in the whole adsorption process and film diffusion was the rate-controlling procedure. Theoretical calculations put forward the most favorable bonding modes between Fe₃O₄-SiO₂-2DMDPS and PHE molecules, confirmed the π-π interaction was valid and it usually existed in the form of parallel-displaced. This work might aid us to develop effective modification strategy for Fe₃O₄ nanoparticles and expand its application in the PAHs removing field.

An Overview and Evaluation of Highly Porous Adsorbent Materials for Polycyclic Aromatic Hydrocarbons and Phenols Removal from Wastewater

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater.

Assessment of schwertmannite, jarosite and goethite as adsorbents for efficient adsorption of phenanthrene in water and the regeneration of spent adsorbents by heterogeneous fenton-like reaction

Schwertmannite, jarosite or goethite are commonly used to remove metals and/or metalloids from contaminated water via adsorption processes, but it is still unclear whether they can be used as adsorbents to remove hydrophobic organic pollutants (HOCs), such as polycyclic aromatic hydrocarbons (PAHs), from groundwater or wastewater. Here, the feasibility of using these iron (oxyhydr) oxide minerals as adsorbents for phenanthrene (a model PAH) adsorption and regenerating the spent adsorbents via heterogeneous Fenton-like reaction was investigated. Results showed that they exhibited rapid adsorption rates and considerable adsorption capacities for phenanthrene. The maximum Langmuir capacities (Qmax) for phenanthrene adsorption at 28 °C were in an ascending order of goethite (567 μg·g-1) < schwertmannite (727 μg·g-1) < jarosite (2088 μg·g-1). The adsorption process was a spontaneous and exothermic process along with the decrease of randomness at the solid/liquid interfaces, which was influenced by temperature, adsorbent dosage, and the coexistence of inorganic anions. Both schwertmannite and jarosite were superior to goethite in light of their easy separation from the bulk solution after the adsorption processes. A multi-cycle experiment demonstrated that the regeneration efficiency of schwertmannite (97.9-99.7%) was much higher than that of jarosite (80.1-87.2%), and the mineral structure, morphology and functional groups of schwertmannite were not changed during the successive adsorption-regeneration processes. Therefore, among the investigated three iron (oxyhydr) oxide minerals, schwertmannite was an attractive and regenerable adsorbent for the removal of phenanthrene from water owing to its high adsorption capacity, good separation ability, and excellent reusability.

Nanoparticles Used for Extraction of Polycyclic Aromatic Hydrocarbons

This article offers a review on the application of nanoparticles (NPs) that have been used as sorbents in the analysis of polycyclic aromatic hydrocarbons (PAHs). The novel advances in the application of carbon NPs, mesoporous silica NPs, metal, metal oxides, and magnetic and magnetised NPs in the extraction of PAHs from matrix solutions were discussed. The extraction techniques used to isolate PAHs have been highlighted including their advantages and limitations. Methods for preparing NPs and optimized conditions of NPs extraction efficiency have been overviewed since proper extraction procedures were necessary to achieve optimum analytical results. The aim was to provide an overview of current knowledge and information in order to assess the need for further exploration that can lead to an efficient and optimum analysis of PAHs.

Amine-terminated dendritic polymers as a multifunctional chelating agent for heavy metal ion removals

In this study, amine-terminated hyperbranched PAMAM (polyamidoamine) polymer (AT-HBP) was synthesized as a multifunctional chelating agent to remove two heavy metal ions (Cr(III) and Cu(II)) from the simulated wastewater solutions. The AT-HBP was characterized by Fourier transformed infrared (FTIR), dynamic light scattering (DLS), and proton nuclear magnetic resonance (¹H NMR) analysis. The removal process was carried out in two different methods, centrifuged process and ultrafiltration. The concentration of heavy metal ions before and after removal was measured by inductively coupled plasma (ICP) instrument. The removal processes were evaluated by changing different parameters such as solution pH, AT-HBP dosage, and metal ion concentration. To evaluate the extend of binding of heavy metal ions in the presence of AT-HBP the presence of salt in the solution was also examined on the performance of the removal system. The overall results indicated that removal percentages higher than 98% for Cr(III) and 86% for Cu(II) were achieved for heavy metal concentrations of 100 mg/L for both removal process methods. Furthermore, the function of second generation of polypropylenimine (PPI) was compared to AT-HBP. The results reveal that the removal of Cr(III) and Cu(II) ions by AT-HBP were approximately 20% and 10% higher compared to PPI, respectively. Finally, hyperbranched dendritic polymer with lower expenses to synthesize compared to dendrimer underlined favorable properties as a multifunctional chelating agent and enhancement of ultrafiltration process for wastewater treatment. Graphical abstract.

Simultaneous removal of polycyclic aromatic hydrocarbons and heavy metals from water using granular activated carbon

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are dangerous pollutants that commonly co-occur in water. An adsorption study conducted on the simultaneous removal of PAHs (acenaphthylene, phenanthrene) and heavy metals (Cd, Cu, Zn) by granular activated carbon (GAC) showed that, when these pollutants are present together, their adsorption was less than when they were present individually. The adsorptive removal percentage of PAHs (initial concentration 1 mg/L) was much higher than that of heavy metals (initial concentration (20 mg/L). The reduction in adsorption of PAHs by heavy metals followed the heavy metals' adsorption capacity and reduction in the negative zeta potential of GAC order (Cu > Zn > Cd). In contrast, PAHs had little effect on the zeta potential of GAC. The Langmuir adsorption capacities of acenaphthylene (0.31-2.63 mg/g) and phenanthrene (0.74-7.36 mg/g) on GAC decreased with increased metals' concentration with the reduction following the order of the metals' adsorption capacity. The kinetic adsorption data fitted to Weber and Morris plots, indicating intra-particle diffusion of both PAHs and heavy metals into the mesopores and micropores in GAC with the diffusion rates. This depended on the type of PAH and metal and whether the pollutants were present alone or together.

Experimental design data for the zinc ions adsorption based on mesoporous modified chitosan using central composite design method

In the present study, new generation of silica-based mesoporous adsorbents were introduced for the removal of heavy metals with the aim of developing new adsorption technologies in water treatment. The magnetic nanoadsorbent, prepared by modification of SBA-15 with [3-(2-Aminoethylamino) propyl] trimethoxysilane (AEAPTMS)-functionalized chitosan, was applied for the removal of Zn²⁺ from aqueous solution. The synthesized Fe₂O₃@SBA-15-CS-AEAPTMS nanoadsorbent was thoroughly characterized using XRD, TEM, FTIR and BET analysis. In order to determine the optimum condition of Zn²⁺ adsorption on Fe₂O₃@SBA-15-CS-AEAPTMS (3 ml), the experiments were performed based on central composite design in a response surface methodology method. The obtained results were further studied using adsorption kinetic, isotherm and thermodynamic relations which revealed that Zn²⁺ adsorption was spontaneous and endothermic with enhanced adsorption efficiency achieved for higher contents of functional groups. In addition, according to the results, the adsorption process was best conformed to Langmuir isotherm (with R² > 0.99 and q_max = 107.21 mg g^-1) and pseudo second-order kinetic model (with R² > 0.999). The values of standard entropy (DS°) and activation energy (E_a) reduced as the initial concentration was increased and the dominant mechanism was found to be chemisorption.