Adsorption Of Organic Pollutants Research Articles

Simple ultrasonic integration of shapeable, rebuildable, and multifunctional MIL-53(Fe)@cellulose composite for remediation of aqueous contaminants

Metal-organic frames (MOFs) have been recognized as one of the best candidates in the remediation of aqueous contaminants, while the fragile powder shape restricts the practical implementation. In this work, a shapeable, rebuildable, and multifunctional MOF composite (MIL-53@CF) was prepared from MIL-53 (Fe) and cellulose fiber (CF) using a simple ultrasonic method for adsorption and photocatalytic degradation of organic pollutants in wastewater. The results showed MIL-53(Fe) crystals were uniformly growth on CF surfaces and bonded with surface nanofibrils of CF through physical crosslinking and hydrogen bonding. Because of the high bonding strength, the MIL-53@CF composite exhibited an excellent compressive strength (3.53 MPa). More importantly, the MIL-53@CF composite was rebuildable through mechanical destruction followed by re-ultrasonication, suggesting the excellent reusability of MIL-53@CF for water remediation. The MIL-53@CF composite also had high adsorption capacities for methyl orange (884.6 mg·g−1), methylene blue (198.3 mg·g−1), and tetracycline (106.4 mg·g−1). MIL-53@CF composite could degrade TC through photocatalysis. The photocatalytic degradation mechanism was attributed to the Fe(II)/Fe(III) transform cycle reaction of MIL-53 crystal located on MIL-53@CF. Furthermore, the mechanical property and remoldability of MIL-53@CF composite increased its practicability. Comprehensively, MIL-53@CF composite provided a possible strategy to practically apply MOF in the remediation of aqueous contaminants.

Enhanced degradation of methylene blue dye using flexible SiO2–TiO2 nanofiber membranes

Titanium dioxide (TiO2) is widely regarded as one of the most extensively applied photocatalytic semiconductor materials. However, conventional powdered titanium dioxide exhibits certain limitations, including relatively weak light absorption capability, a small surface area and insufficient active sites. This study successfully prepared flexible and porous silicon dioxide (SiO2)–titanium dioxide nanofiber membranes (NFMs) by implementing electrospinning technology and calcination processes. The porous membranes demonstrate remarkable performance in water treatment, featuring a high specific surface area (49 m2/g) and porosity, enabling efficient adsorption and removal of organic pollutants in water. Remarkably, the NFMs-800 variant exhibits outstanding photocatalytic performance, achieving complete removal of adsorbed organic compounds under ultraviolet irradiation. The design and fabrication methods of this porous membrane are simple and scalable, providing a potential solution for practical water-treatment applications. Consequently, the silicon dioxide–titanium dioxide porous membrane holds significant prospects in the field of water treatment, offering a promising contribution to the attainment of efficient and sustainable water resource management.

Synthesis of zeolitic imidazole framework‐8 derived ZnCo layered double hydroxides for the removal of methylene blue from wastewater

AbstractThe development of highly efficient and cost‐effective materials for water treatment is paramount and the preparation of metal–organic framework‐derived layer double hydroxide (MOF‐LDH) is an area of great interest. In this study, an innovative adsorbent material zeolitic imidazole framework‐8 (ZIF‐8) derived ZnCo layered double hydroxides was prepared by in situ growth for the adsorption of cationic methylene blue (MB) dye from wastewater. Analytical tools such as FTIR, SEM, and XRD were used to characterize the composite material. Different adsorption parameters like initial dye concentration, pH, temperature, contact time, adsorption mechanisms, and density functional theory (DFT) mechanisms were studied which showed that the derived material significantly enhanced the adsorption capacity which was 502.51 mg/g at pH 11. DFT analyses suggested that MB possessed interaction sites favorable to adsorbent material. The adsorption kinetic model showed that pseudo‐second‐order had a good correlation coefficient (R2 = 0.99983) value proposing the chemisorption adsorption phenomenon. Both the Langmuir and Freundlich isotherm models are well fitted in experimental data as both have good correlation coefficient (R2 = 0.99771) and (R2 = 0.99856) values respectively but the best fit of the adsorption isotherm data was achieved with the Freundlich model, indicating multilayer adsorption characteristics. The experimental and theoretical analyses demonstrated that the fabricated adsorbent is a highly efficient material for the adsorption of organic pollutants from an aqueous medium.

Mechanistic insight into the enhanced photodegradation by black titanium dioxide nanofiber-graphene quantum dot composites

The photocatalytic activity of black titanium dioxide nanofibers (bTiO2 NFs) can be enhanced through composition with carbon nanomaterials. However, it is unclear whether enhanced charge separation or increased surface adsorption of organic pollutants to the nanocomposite surfaces is the dominant contributor. This knowledge gap was filled when we sought to enhance the surface contact of carbon with the bTiO2 NFs by using graphene quantum dots (GQDs) hypothesizing that this would further enhance photocatalytic activity. The results showed a similar Rhodamine B (RhB) photodegradation rate between the optimal loadings of GQDs and RGO we reported previously. This allowed for further elucidation of the enhancement mechanism, where charge carrier separation enhancement at the photocatalyst surface is the dominant effect, whereas RhB adsorption does not make significant contribution. This significant insight enhances our understanding towards engineering highly efficient composite photocatalysts for organic pollutant removal in water.

Aquatic toxicity of hydroquinone and catechol following metal oxide treatment to Ceriodaphnia dubia and Pimephales promelas.

Metal oxides comprise a large group of chemicals used in water treatment to adsorb organic pollutants. The ability of titanium dioxide (TiO2) and iron (III) oxide (Fe2O3) to reduce the chronic toxicity of (phenolic) C6H6(OH)2 isomers, namely hydroquinone (HQ) and catechol (CAT) to Ceriodaphnia dubia and Pimephales promelas (less than 24 h-old) were investigated. The toxic endpoints following metal oxide treatment were compared to endpoints of untreated CAT and HQ. In chronic toxicity testing, HQ resulted in greater toxicity than CAT for both test organisms; the median lethal concentrations (LC50) for CAT were 3.66 to 12.36 mg.L-1 for C. dubia and P. promelas, respectively, while LC50 for HQ were 0.07 to 0.05 mg.L-1, respectively. Although both treated solutions presented lower toxic endpoints than those in the untreated solutions, Fe2O3 had a better potential to reduce the toxic effects of CAT and HQ than TiO2.

Surface chemistry regulation of nanoparticle coatings on activated carbons for rapid and long-lasting adsorption of organic pollutants

The nature of activated carbons (AC) to possess large specific surface areas and highly developed internal channels, is beneficial to absorb a variety of organic pollutants for practical applications in widespread areas, such as odor removal, flue gas cleaning and water purification. However, the domination of water affinity on AC could promote the adsorption to saturation in a short period, hindering the adsorptive performance on organics and reducing the service life severely. Thus, a simultaneous demonstration of the remarkable adsorptive property along with moisture resistance is of great significance. In this work, the superhydrophobic ACs with selective adsorptive property were fabricated via the combination of pretreatment to roughen the surface and grafting of propyl trimethoxysilane on superhydrophobic nanoparticles. The design was verified by the theoretical calculation of density functional theory accompanied with surface grafting ratio, and the as-prepared ACs presented favorable damp- and water-proof ability in the long term, showing only 11.8% weight increment for up to 180 days in high humidity. More importantly, superhydrophobic ACs exhibited effective capture of organics for continuous adsorption under aqueous phase and humid conditions, with removal efficiency over 90%.

Ni4 complex anchored porous silica for enhanced adsorption of organic pollutants in the wastewater.

In the current study, tetranuclear Ni complex [Ni4(LH)4]·CH3CN (1) (LH3=(E)-2-(hydroxymethyl)-6-(((2-hydroxyphenyl)imino)methyl)phenol) was prepared and incorporated in sulfonic acid functionalized MCM-48 material. This composite nanoporous material was investigated for the adsorption of toxic cationic water pollutant dyes like crystal violet (CV) and methylene blue (MB) from the water solution. Thorough characterization was carried out using a variety of techniques, including NMR, ICP, powder XRD, TGA, SEM, BET, and FT-IR, to verify the phase purity, existence of guest moiety, material morphology, and other crucial variables. The adsorption property was increased with the metal complex immobilization on the porous support. The effect of various parameters on the adsorption process was discussed, including adsorbent dosage, temperature, pH, NaCl concentration, and contact time. Maximum dye adsorption was found at 0.2 mg/ml adsorbent dosage, 10 ppm dye concentration, 6-7 pH, 25 °C temperature, and 15 minutes of contact time. The adsorption of MB (methylene blue) and CV (crystal violet) dyes by Ni complex integrated MCM-48 was effective, with over 99% adsorption achieved in 15 minutes. A recyclability test was also performed, and the material is reusable up to the third cycle, with no notable decline in adsorption found. From the previous literature survey, it is clear that very high adsorption efficiency was achieved using MCM-48-SO3-Ni in considerably short contact time which proves the novelty and effectiveness of the modified material. Ni4 was prepared, characterized, and immobilized in sulfonic acid functionalized MCM-48, and this robust and reusable adsorbent was highly effective for the adsorption of methylene blue and crystal violet dyes with >99% adsorption efficiency in short duration.

Carbon Adsorbents Obtained from Pistachio Nut Shells Used as Potential Ingredients of Drinking Water Filters.

Water resources are increasingly degraded due to the discharge of waste generated in municipal, industrial and agricultural areas. Therefore, the search for new materials enabling the effective treatment of drinking water and sewage is currently of great interest. This paper deals with the adsorption of organic and inorganic pollutants on the surface of carbonaceous adsorbents prepared by thermochemical conversion of common pistachio nut shells. The influence of the direct physical activation with CO2 and chemical activation with H3PO4 on parameters, such as elemental composition, textural parameters, acidic-basic character of the surface as well as electrokinetic properties of the prepared carbonaceous materials was checked. The suitability of the activated biocarbons prepared as the adsorbents of iodine, methylene blue and poly(acrylic acid) from the aqueous solutions was estimated. The sample obtained via chemical activation of the precursor turned out to be much more effective in terms of all the tested pollutants adsorption. Its maximum sorption capacity toward iodine was 1059 mg/g, whereas in relation to methylene blue and poly(acrylic acid) 183.1 mg/g and 207.9 mg/g was achieved, respectively. For both carbonaceous materials, a better fit to the experimental data was achieved with a Langmuir isotherm than a Freundlich one. It has also been shown that the efficiency of organic dye, and especially anionic polymer adsorption from aqueous solutions, is significantly affected by solution pH and temperature of the adsorbate-adsorbent system.

BiOI/Bi2MoO6 p-n Junction to Enhance Visible Light Photocatalytic Activity toward Environmental Remediation.

Photocatalytic degradation of organic pollutants via semiconductors with high visible light response and effective carrier separation is an economical and green route to greatly achieve environmental remediation. Herein, an efficient BiOI/Bi2MoO6 p-n heterojunction was in situ fabricated through hydrothermal method by substituting Mo7O246- species for I ions. The characteristic p-n heterojunction exhibited a strongly enhanced visible light responsive absorption from 500 to 700 nm owing to the narrow band gap of BiOI and a greatly effective separation of photoexcited carriers because of the built-in electric field on the interface between BiOI and Bi2MoO6. Moreover, the flower-like microstructure also promoted the adsorption of organic pollutants owing to the large surface area (about 10.36 m2/g), good for further photocatalytic degradation. As a result, BiOI/Bi2MoO6 p-n heterojunction showed an excellent photocatalytic activity of RhB of almost 95% in a short time of 90 min under wavelength longer than 420 nm, 2.3 and 2.7 times higher compared with single BiOI and Bi2MoO6, respectively. This work offers a promising approach to purify the environment through the utilization of solar energy by constructing efficient p-n junction photocatalysts.

Chitin/deacetylated chitin nanocomposite film for effective adsorption of organic pollutant from aqueous solution

Cross-linked chitin/deacetylated chitin nanocomposite films can be considered as a potential industrial adsorbent for the removal of organic pollutants for water purification. Chitin (C) and deacetylated chitin (dC) nanofibers were extracted from raw chitin and characterized using FTIR, XRD and TGA techniques. The TEM image confirmed the formation of chitin nanofibers with a diameter range of 10–45 nm. The deacetylated chitin nanofibers (DDA-46 %) having 30 nm diameter was evidenced using FESEM. Further, the C/dC nanofibers were prepared at different ratios (80/20, 70/30, 60/40 & 50/50 ratios) and cross-linked. The highest tensile strength of 40 MPa and Young's modulus of 3872 MPa was exhibited by 50/50C/dC. The DMA studies revealed that the storage modulus enhanced by 86 % for 50/50C/dC (9.06 GPa) in comparison to 80/20C/dC nanocomposite. Further, the 50/50C/dC exhibited a maximum adsorption capacity of 30.8 mg/g at pH = 4 in 30 mg/L of Methyl Orange (MO) dye within 120 min. The experimental data agreed with pseudo-second-order model indicating chemisorption process. The adsorption isotherm data was best described by Freundlich model. The nanocomposite film is an effective adsorbent that can be regenerated and recycled for five adsorption-desorption cycle.

Synthesis of magnetic carbon composite by diesel engine and its application to dye removal

We report a one-step and efficient method to synthesize magnetic diesel particles (MDPs) and their application toward dye removal. The MDPs were obtained by the combustion of ferrocene-doped diesel fuel using an internal combustion engine. The diesel particles combined with ferrocene as a metal source were collected by an electrostatic precipitator. The thermogravimetric analysis confirmed the ferrocene-based catalyst and thermal stability of MDPs. FE-SEM showed irregular and aggregated morphologies, and the presence of iron oxide phases (Fe4O3 and γ-Fe2O3) was confirmed by X-ray diffraction analysis. The characteristics of MDPs as an adsorbent for organic pollutants were evaluated by methylene blue (MB) adsorption experiments. Langmuir isotherm and pseudo-second-order models best interpret the adsorption process and kinetics, respectively, with a maximum adsorption capacity of 40.81 mg/g of MB adsorbed on the surface of magnetic diesel particles.

Imatinib cation based MOIFs with [Fe(CN)5NO]2−, [Fe(CN)6]3− [Fe(CN)6]4− as adsorbent of organic pollutants, and their protein interaction study

Inorganic-organic hybrid (IOH) compounds are being widely used in the design of multifunctional materials owing to their rich properties and flexible assembly. Here, we report three metal organic ionic frameworks (MOIFs)/ IOH, for the adsorption of toxic organic pollutants and Bovine Serum Albumin (BSA) interaction, synthesized via simple ion-exchange mechanism in water using Na2[Fe(CN)5NO], K3[Fe(CN)6], K4[Fe(CN)6] and 4-[(4-methylpiperazin-1-yl)methyl]-N-(4-methyl-3-{[4-(pyridin-3-yl)pyrimidin-2yl]amino}phenyl) mesylate (ImM). These were characterized through powder XRD, NMR, UV/ Vis and FTIR techniques for their structural elucidation. The thermal gravimetric analysis (TGA) revealed their two transitions due to loss of water and organic compound. Additionally, the band gap was found in the range of 3.2 to 3.3 eV, inferred their applicability in the field of semiconductors. MOIFs have shown the adsorption of toxic pollutants (Organic dyes) investigated through thermal kinetics and activation parameters which inferred about the interaction between organic dyes and MOIFs as characteristics for the adsorption system. Adsorption has also been analyzed through conductivity data where according to Ostwald's dilution law for weak electrolytes was applied. For knowing medicinal aspects, MOIFs have also been tested for BSA binding activity analyzed with UV–Vis, fluorescence and docking studies, which showed good quenching efficacy as well as interaction ability.

Nitrogen coordination modulation of single-atom CoN4 enables dual-active-sites catalyst featuring synergistic organics adsorption and peroxymonosulfate activation

Minimizing the migration distance of short-lived radicals to targets is highly desirable for maximizing the heterogeneous Fenton-like catalytic performance. Herein, we design and fabricate a difunctional CoN4 single-atom catalyst, CoN4(29% pyrrolic N), composed of 29% pyrrole-type Co–N4 and 71% pyridine-type Co–N4 centers via atomic-level nitrogen coordination modulation, which enables dual-active-sites featuring synergistic peroxymonosulfate (PMS) activation and organic pollutant adsorption. Theoretical prediction and experiments demonstrate that the isolated Co site in pyridine-type Co–N4 has a relatively strong interaction with PMS than that in pyrrole-type Co–N4 because that the pyridinic N is more able to alter and optimize the electron distribution of the Co 3d orbital, namely an increased d-band center closer to the Fermi level and induced low spin-state Co formation, and thus facilitate electron transfer, enhance PMS adsorption, and reduce energy barriers of PMS activation. Meanwhile, the targets, including bisphenol A and other emerging pollutants, can be effectively adsorbed onto the pyrrolic N site in pyrrole-type Co–N4 via a “hard-soft interaction” principle and “donor–acceptor complex” process. This strategy minimizes essentially the mass transport limitation of the reaction by greatly reducing the transport distance of radicals towards pollutants. That is, the CoN4(29% pyrrolic N) can effectively induce the spatial confinement to restrict the space where the Fenton-like catalytic oxidaiton occurs in the vicinity of pollutants adsorbed, achieving rapid and effcient degradation and removal of emergying pollutants from water and wastewater.

Biomass-derived carbon nano-onions for the effective elimination of organic pollutants and oils from water.

Oil spillage and leakage of organic solvents have caused severe environmental and ecological damages. It is of great significance to develop a cost-efficient and green adsorbent material with high uptake efficiency to separate the oil-water mixture. In this work, biomass-derived CNOs were first time explored in the adsorption of organic pollutants and oils from water. Carbon nano-onions (CNOs) with hydrophobicity and oleophilicity were cost-effectively synthesized in an energy efficient flame pyrolysis process using flaxseed oil as a carbon source. The as-synthesized CNOs without any further surface modification have shown high adsorption efficiency in removing organic solvents and oils from the oil-water mixture. The CNOs could adsorb diverse organic solvents such as pyridine (36.81 mg g-1), dichloromethane (90.95 mg mg-1), aniline (76 mg mg-1), toluene (64 mg mg-1), chloroform (36.25 mg mg-1), methanol (49.25 mg mg-1), and ethanol (42.25 mg mg-1). The uptake capacity for petrol and diesel over CNOs was observed at 36.68 mg mg-1 and 58.1 mg mg-1, respectively. The adsorption of pyridine followed pseudo-second-order kinetics and Langmuir's isotherm model. Moreover, the adsorption efficiency of CNOs towards the remediation of pyridine was almost similar in real-water samples when tested in tap water, dam water, groundwater, and lake water. Similarly, the practical applicability for the separation of petrol and diesel was also verified in the real sample (sea water) and has been proven to be excellent. By simple evaporation, the recovered CNOs can be reused for more than 5 cycles. CNOs exhibit the promising potential to be used in practical applications for oil-polluted water treatment.

A novel MIL-125(Ti)-based nanocomposite for enhanced adsorption and catalytic degradation of tetracycline hydrochloride: Synergetic mechanism of calcination and the nitrogen-containing reticulated surface layer

A multi-nitrogen conjugated organic molecule (TPE-2Py) was selected to surface modify the calcined MIL-125(Ti) to prepare a nanocomposite (TPE-2Py@DSMIL-125(Ti)) for adsorption and photodegradation of organic pollutant (tetracycline hydrochloride) under visible light. A novel reticulated surface layer was formed on the nanocomposite, and the adsorption capacity of TPE-2Py@DSMIL-125(Ti) for tetracycline hydrochloride can reach 157.7 mg/g under neutral conditions, which is higher than that of most other reported materials. Kinetic and thermodynamic studies show that the adsorption is a spontaneous heat absorption process, dominated by chemisorption, in which electrostatic interaction, π-π conjugation and Ti-N covalent bonds played dominant roles. The photocatalytic study shows that the visible photo-degradation efficiency of TPE-2Py@DSMIL-125(Ti) for tetracycline hydrochloride can further reach 89.1% after adsorption. Mechanism studies reveal that •O2− and h+ play a major role in the degradation process, and the separation and transfer rate of photo-generated carriers increase, improving its visible photocatalytic performance. This study revealed the relationship between the adsorption/photocatalytic properties of the nanocomposite and the structure of the molecular as well as the calcination, providing a convenient strategy to regulate the removal efficiency of MOFs materials towards organic pollutants. Furthermore, TPE-2Py@DSMIL-125(Ti) exhibits good reusability and even better removal efficiency for tetracycline hydrochloride in real water samples, indicating its sustainable treatment of pollutants in contaminated water.

Chitosan/carboxymethylcellulose polyelectrolyte complexes (PECs) are an effective material for dye and heavy metal adsorption from water

Granular macroscopic chitosan/carboxymethylcellulose polyelectrolytic complexes (CHS/CMC macro-PECs) were produced and tested as adsorbents for six pollutants often present in wastewaters: sunset yellow (YS), methylene blue (MB), Congo red (CR) and safranin (S), cadmium (Cd2+) and lead (Pb2+). The optimum adsorption pH values at 25 °C were 3.0, 11.0, 2.0, 9.0, 10.0, and 9.0 for YS, MB, CR, S, Cd2+, and Pb2+, respectively. Kinetic studies indicated that the pseudos-econd order model best represented the adsorption kinetics of YS, MB, CR, and Cd2+, whereas the pseudo-first order model was the most suitable for S and Pb2+ adsorption. The Langmuir, Freundlich, and Redlich-Peterson isotherms were fitted to experimental adsorption data, with the Langmuir model providing the best fit. The maximum adsorption capacity (qmáx) of CHS/CMC macro-PECs for the removal of YS, MB, CR, S, Cd2+, and Pb2+ was 37.81, 36.44, 70.86, 72.50, 75.43, and 74.42 mg/g, respectively (corresponding to 98.91 %, 94.71 %, 85.73 %, 94.66 %, 98.46 %, and 97.14 %). Desorption assays showed that CHS/CMC macro-PECs can be regenerated after adsorbing any of the six pollutants studied, with possibility of reuse. These results provide an accurate quantitative characterization of the adsorption of organic and inorganic pollutants on CHS/CMC macro-PECs, indicating a novel technological applicability of these two inexpensive, easy-to-obtain polysaccharides for water decontamination.

A review on covalent organic frameworks as adsorbents for organic pollutants

A review on covalent organic frameworks as adsorbents for organic pollutants

Photocatalytic Degradation and Adsorptive Removal of Emerging Organic Pesticides Using Metal Oxide and Their Composites: Recent Trends and Future Perspectives

For applications involving water cleanup, metal oxide nanoparticles are exceptionally successful. They are useful for the adsorption and photocatalytic destruction of organic pollutants due to their distinctive qualities, which include their wide surface/volume area, high number of active sites, porous structure, stability, recovery, and low toxicity. Metal oxide nanomaterials have drawn a lot of attention from researchers in the past ten years because of their various production pathways, simplicity in surface modification, abundance, and inexpensive cost. A wide range of metal oxides, such as iron oxides, MgO, TiO2, ZnO, WO3, CuO, Cu2O, metal oxides composites, and graphene–metal oxides composites, with variable structural, crystalline, and morphological features, are reviewed, emphasizing the recent development, challenges, and opportunities for adsorptive removal and photocatalytic degradation of organic pollutants such as dyes, pesticides, phenolic compounds, and so on. In-depth study of the photocatalytic mechanism of metal oxides, their composites, and photocatalytically important characteristics is also covered in this paper. Metal oxides are particularly effective photocatalysts for the degradation of organic pollutants due to their high photodegradation efficiency, economically sound methods for producing photo-catalytic materials, and precise band-gap engineering. Due to their detrimental effects on human health, pesticides—one of the highly hazardous organic pollutants—play a significant part in environmental contamination. Depending on where they come from and who they are targeting, they are categorized in various ways. Researchers focusing on metal oxides and their composites for the adsorptive and photocatalytic degradation of pesticides would find the review to be a beneficial resource. Detailed information on many pesticides, difficulties associated with pesticides, environmental concentration, and the necessity of degradation has been presented.

Preparation of direct Z-scheme hierarchical MoS2/MnO2 composite for efficient adsorption and wide spectrum photocatalytic degradation of organic pollutants in water

Developing semiconductor-based heterogeneous photocatalysts with high adsorption performance and wide light response range is a significant technology for removing organic pollutants from water. Herein, a novel hierarchical dendritic-like direct Z-scheme MoS2/MnO2 composite with MoS2 hollow tubular decorated by MnO2 nanosheets was successfully fabricated by vacuum freeze-drying. When the mass ratio of MoS2/MnO2 is 3:1, the highest adsorption-photocatalytic removal rate of 94.5% and 95.1% in 120 min for RhB was attained under visible (Vis) and ultraviolet (UV) light irradiation, respectively. After three repeated uses, the removal rate of RhB still reached 91.1%. The enhanced adsorption-photocatalytic performance of the composite can be well illustrated according to the hierarchical composite structure, production of •OH, •O2− and h+ active species, oxygen-doping in the MoS2 and the direct Z-scheme photocatalytic mechanism. This work gives a good strategy to frame hierarchical Z-scheme photocatalysts for efficient adsorption and wide-spectrum photocatalytic removal of organic pollutants from water.

Adsorption Characteristics and Influencing Factors of Chlorinated and Aromatic Hydrocarbons on Aquifer Medium

To determine the competitive adsorption characteristics and influencing factors of chlorinated and aromatic hydrocarbons on the aquifer medium, toluene, benzene, 1,2−dichloropropane, and 1,2,3−trichloropropane (TCP) were selected as typical pollutants for adsorption tests. The results showed that the adsorption process of pollutants on the aquifer medium conformed to the first−order kinetic and Henry linear model equation, and the adsorption capacity decreased in the order of toluene, benzene, 1,2−dichloropropane, and TCP. Benzene promoted the adsorption of toluene on the aquifer medium, while toluene reduced the adsorption of benzene conversely. 1,2−dichloropropane restrained the adsorption of TCP, and TCP had no significant effect on the adsorption of 1,2−dichloropropane. The adsorption capacity of TCP on the aquifer increased with the concentration of toluene. TCP acted as a stimulus for the adsorption of toluene when the initial concentration of toluene was lower than 2 mg/L. In contrast, TCP served as an inhibitor for the adsorption of toluene on the aquifer medium. Furthermore, the adsorption of all pollutants increased with decreasing medium size. The promotion rates for aromatic and chlorinated hydrocarbons were 7.2~41.1% and 2.7~27.1%, suggesting that the promotion effect on aromatic hydrocarbons was stronger than that on chlorinated hydrocarbons. Natural organic matter (NOM) inhibited the adsorption of pollutants on the aquifer medium (especially for high concentrations of chlorinated hydrocarbons), and the adsorption rate increased by more than 60% when OM decreased from 0.25% to 0.08%. Clay minerals improved the adsorption of organic pollutants in different compound pollution systems, and montmorillonite exhibited a stronger promoting effect than kaolin.