Adsorption of heavy metals on molybdenum disulfide in water: A critical review

Removal of nickel ions from industrial wastewater using tms-EDTA-functionalized Ti3C2Tx: Experimental and statistical physics modeling

This study investigates the surface modification of Ti3C2Tx MXene using tms-EDTA (EDTA@MXene) to develop an efficient adsorbent for divalent heavy metal cations, such as Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺, from contaminated water. EDTA@MXene showed significantly enhanced adsorption capacities for these ions compared to pristine MXene. Using nickel ion (Ni²⁺) as a model adsorbate, EDTA@MXene demonstrated remarkable removal efficiency, reaching a maximum adsorption capacity of 249.5 mg/g as compared to the 61.4 mg/g of pristine MXene with fast kinetics and attaining equilibrium within 30 min. The results indicated that Ni²⁺ adsorption followed a pseudo-second-order kinetic model, with equilibrium data fitting both Langmuir and Freundlich isotherm models. As the classical adsorption models remained inconclusive on the underlying adsorption mechanisms, advanced statistical physics models were subsequently applied for deeper investigation. The findings revealed that Ni²⁺ ions adsorbed onto the surface in a non-parallel orientation. The adsorption process was reversible, endothermic, and driven mainly by physical interactions, with higher temperatures favoring greater adsorption capacity. EDTA@MXene demonstrated excellent reusability, maintaining high (>80 %) regeneration efficiency after five regeneration cycles. It also exhibited a high adsorption capacity for Ni²⁺ ions from nickel electroplating wastewater, highlighting its potential for real application in the treatment of metal-contaminated industrial wastewater.

Chitosan-based porous composites embedded with molybdenum disulfide nanosheets for removal of mercury from wastewater

Mercury-containing wastewater presents a significant environmental threat due to its high toxicity. Therefore, the urgent removal of mercury-laden wastewater is essential to protect ecosystems and public health. In this study, molybdenum disulfide (MoS2) nanosheets modified with a silane coupling agent (designated as MS) were crosslinked with natural polymer chitosan (CS) rich in -NH2 and - OH groups to develop a highly efficient and environmentally friendly MoS2-functionalized three-dimensional reticulated porous materials (denoted as MS/CTS) composite adsorbent. Following adsorption, the concentration of mercury ions in wastewater was significantly reduced from an initial level of 1000 μg∙L-1 to just 0.88 μg∙L-1, which is below the acceptable limit for drinking water. Furthermore, it showed excellent acid resistance, maintaining a removal efficiency of 99.71 % for a starting level of 587.8 mg·L-1 at a pH as low as 3.5. The adsorption capacity of composite exceeded the mathematical sum of the adsorption capacities of MS and pure chitosan adsorbent was prepared according to the same procedure without adding MS (denoted as CTS) at the same ratio. The saturated adsorption capacity fitted by Langmuir-Freundlich model is 1429.69 mg·g-1, which is very close to the experimental value of 1317.70 mg·g-1. The MS/CTS displays a selectivity for metal ions in the following order: Hg(II) > Pb(II) > Cu(II) > Cd(II), along with exceptionally high distribution coefficients (Kd) of 1.99 × 105 mL·g-1 for Hg(II). Even after five cycles of reuse, the mercury removal efficiency remained above 85 %. Mechanistic analysis indicated that both monolayer and multilayer chemical adsorption were involved in mercury removal. The high adsorption capacity was attributed to the synergistic effect of S, N, and - O functional groups. After adsorption, mercury ions existed on the surface of the adsorbent in the form of a hollow net-like Hg3S2Cl2. These findings significantly expand the application scope of MoS2/biomass composites in environmental remediation.

Piezoelectric catalytic driven advanced oxidation process using two-dimensional metal dichalcogenides for wastewater pollutants remediation

The public and society have increasingly recognized numerous grave environmental issues, including water pollution, attributed to the rapid expansion of industrialization and agriculture. Renewable energy-driven catalytic advanced oxidation processes (AOPs) represent a green, sustainable, and environmentally friendly approach to meet the demands of environmental remediation. In this context, 2D transition metal dichalcogenides (TMDCs) piezoelectric materials, with their non-centrosymmetric crystal structure, exhibit unique features. They create dipole polarization, inducing a built-in electric field that generates polarized holes and electrons and triggers redox reactions, thereby facilitating the generation of reactive oxygen species for wastewater pollutant remediation. A broad spectrum of 2D TMDCs piezoelectric materials have been explored in self-integrated Fenton-like processes and persulfate activation processes. These materials offer a more simplistic and practical method than traditional approaches. Consequently, this review highlights recent advancements in 2D TMDCs piezoelectric catalysts and their roles in wastewater pollutant remediation through piezocatalytic-driven AOPs, such as Fenton-like processes and sulfate radicals-based oxidation processes.

A strategy for the preparation of super-hydrophilic molybdenum disulfide composites applied to remove uranium from wastewater

Due to the radioactivity of uranium, the discharged nuclear wastewater not only causes certain damage to the ecology, but also causes certain harm to human life and health. Adsorption is considered to be one of the most effective ways to remove uranium. In this paper, a kind of MoS2 adsorbent was prepared by the solid phase synthesis method and functionalized with NiCo-LDH. The raw materials of MoS2 are cheap and easy to obtain, and the preparation conditions are simple, and large quantities can be obtained without limitations. MoS2 functionalized with NiCo-LDH provides more adsorption sites for the adsorbent and at the same time improves the hydrophilicity of the adsorbent, so that the active sites can fully combine with uranyl ions. The maximum adsorption capacity of the Langmuir isothermal adsorption model is 492.83 mg g-1. The selective adsorption capacity of uranium can reach 76.12% in the multi-ion coexistence system. By analyzing the adsorption mechanism with FT-IR and XRD, it is believed that on the one hand, UO22+ forms a covalent bond with Mo in MoS2 and coordinates with S on the surface of MoS2. On the other hand, UO22+ enters the NiCo-LDH layer for ion exchange with NO3- and coordinates with -OH on the surface of NiCo-LDH. The successful preparation of the MoS2/NiCo-LDH composite provides a certain application prospect for the uranium adsorption field.

Recent advances in cellulose- and alginate-based hydrogels for water and wastewater treatment: A review

From the environmental perspective, it is essential to develop cheap, eco-friendly, and highly efficient materials for water and wastewater treatment. In this regard, hydrogels and hydrogel-based composites have been widely employed to mitigate global water pollution as this methodology is simple and free from harmful by-products. Notably, alginate and cellulose, which are natural carbohydrate polymers, have gained great attention for their availability, price competitiveness, excellent biodegradability, biocompatibility, hydrophilicity, and superior physicochemical performance in water treatment. This review outlined the recent progress in developing and applying alginate- and cellulose-based hydrogels to remove various pollutants such as dyes, heavy metals, oils, pharmaceutical contaminants, and pesticides from wastewater streams. This review also highlighted the effects of various physical or chemical methods, such as crosslinking, grafting, the addition of fillers, nanoparticle incorporation, and polymer blending, on the physiochemical and adsorption properties of hydrogels. In addition, this review covered the alginate- and cellulose-based hydrogels' current limitations such as low mechanical performance and poor stability, while presenting strategies to improve the drawbacks of the hydrogels. Lastly, we discussed the prospects and future directions of alginate- and cellulose-based hydrogels. We hope this review provides valuable insights into the efficient preparations and applications of hydrogels.

Nanotechnology for endorsing abiotic stresses: a review on the role of nanoparticles and nanocompositions

Environmental stresses, including the salt and heavy metals contaminated sites, signify a threat to sustainable crop production. The existence of these stresses has increased in recent years due to human-induced climate change. In view of this, several remediation strategies including nanotechnology have been studied to find more effective approaches for sustaining the environment. Nanoparticles, due to unique physiochemical properties; i.e. high mobility, reactivity, high surface area, and particle morphology, have shown a promising solution to promote sustainable agriculture. Crop plants easily take up nanoparticles, which can penetrate into the cells to play essential roles in growth and metabolic events. In addition, different iron- and carbon-based nanocompositions enhance the removal of metals from the contaminated sites and water; these nanoparticles activate the functional groups that potentially target specific molecules of the metal pollutants to obtain efficient remediation. This review article emphasises the recent advancement in the application of nanotechnology for the remediation of contaminated soils with metal pollutants and mitigating different abiotic stresses. Different implementation barriers are also discussed. Furthermore, we reported the opportunities and research directions to promote sustainable development based on the application of nanotechnology.

Adsorption of Rhodamine B and Pb(II) from aqueous solution by MoS2 nanosheet modified biochar: Fabrication, performance, and mechanisms

Mediated by polydopamine, MoS2 nanosheets were immobilized on the porous biochar derived from fungus residue, forming a novel biochar-based nanocomposite (MoS2-PDA@FRC) for the removal of Rhodamine B(RhB) and Pb(II) from water. Utilizing MoS2 nanosheets with abundant active adsorption sites, MoS2-PDA@FRC showed higher adsorption capacities than raw biochar, with 2.76 and 1.78 times higher capacities for RhB and Pb(II) respectively. MoS2-PDA@FRC also exhibited fast adsorption kinetics for RhB (120 min) and Pb (180 min) removal, as well as satisfactory adsorption selectivity in the presence of coexisting substances. The underlying removal mechanism was explored via Fourier transform infrared and X-ray photoelectron spectroscopies. Furthermore, during cyclic adsorption-regeneration and the fixed-bed adsorption experiments, the nanocomposite removed RhB and Pb(II) with high effectiveness and stability. Collectively, the results demonstrated the bright prospects of MoS2-PDA@FRC as a highly efficient decontamination agent of RhB and Pb(II) from water.

Heteroatom-Doped Molybdenum Disulfide Nanomaterials for Gas Sensors, Alkali Metal-Ion Batteries and Supercapacitors

Molybdenum disulfide (MoS2) is the second two-dimensional material after graphene that received a lot of attention from the research community. Strong S-Mo-S bonds make the sandwich-like layer mechanically and chemically stable, while the abundance of precursors and several developed synthesis methods allow obtaining various MoS2 architectures, including those in combinations with a carbon component. Doping of MoS2 with heteroatom substituents can occur by replacing Mo and S with other cations and anions. This creates active sites on the basal plane, which is important for the adsorption of reactive species. Adsorption is a key step in the gas detection and electrochemical energy storage processes discussed in this review. The literature data were analyzed in the light of the influence of a substitutional heteroatom on the interaction of MoS2 with gas molecules and electrolyte ions. Theory predicts that the binding energy of molecules to a MoS2 surface increases in the presence of heteroatoms, and experiments showed that such surfaces are more sensitive to certain gases. The best electrochemical performance of MoS2-based nanomaterials is usually achieved by including foreign metals. Heteroatoms improve the electrical conductivity of MoS2, which is a semiconductor in a thermodynamically stable hexagonal form, increase the distance between layers, and cause lattice deformation and electronic density redistribution. An analysis of literature data showed that co-doping with various elements is most attractive for improving the performance of MoS2 in sensor and electrochemical applications. This is the first comprehensive review on the influence of foreign elements inserted into MoS2 lattice on the performance of a nanomaterial in chemiresistive gas sensors, lithium-, sodium-, and potassium-ion batteries, and supercapacitors. The collected data can serve as a guide to determine which elements and combinations of elements can be used to obtain a MoS2-based nanomaterial with the properties required for a particular application.

Preparation and Photocatalytic Performance of MoS2/MoO2 Composite Catalyst

Solar energy is an inexhaustible clean energy providing a key solution to the dual challenges of energy and environmental crises. Graphite-like layered molybdenum disulfide (MoS₂) is a promising photocatalytic material with three different crystal structures, 1T, 2H and 3R, each with distinct photoelectric properties. In this paper, 1T-MoS₂ and 2H-MoS₂, which are widely used in photocatalytic hydrogen evolution, were combined with MoO₂ to form composite catalysts using a bottom-up one-step hydrothermal method. The microstructure and morphology of the composite catalysts were studied by XRD, SEM, BET, XPS and EIS. The prepared catalysts were used in the photocatalytic hydrogen evolution of formic acid. The results show that MoS₂/MoO₂ composite catalysts have an excellent catalytic effect on hydrogen evolution from formic acid. By analyzing the photocatalytic hydrogen production performance of composite catalysts, it suggests that the properties of MoS₂ composite catalysts with different polymorphs are distinct, and different content of MoO₂ also bring differences. Among the composite catalysts, 2H-MoS₂/MoO₂ composite catalysts with 48% MoO₂ content show the best performance. The hydrogen yield is 960 µmol/h, which is 1.2 times pure 2H-MoS₂ and two times pure MoO₂. The hydrogen selectivity reaches 75%, which is 22% times higher than that of pure 2H-MoS₂ and 30% higher than that of MoO₂. The excellent performance of the 2H-MoS₂/MoO₂ composite catalyst is mainly due to the formation of the heterogeneous structure between MoS₂ and MoO₂, which improves the migration of photogenerated carriers and reduces the possibilities of recombination through the internal electric field. MoS₂/MoO₂ composite catalyst provides a cheap and efficient solution for photocatalytic hydrogen production from formic acid.

Facile green preparation of single- and two-component modified activated carbon fibers for efficient trace heavy metals removal from drinking water

Trace heavy metals exist in drinking water, having great adverse effects on human health and making it a huge challenge to remove. Herein, novel materials have been prepared by a simple and green method using single- (polydopamine (PDA) or 2,3-dimercaptopropanesulfonic sodium (DMPS)) (PDA-OACF or DMPS-OACF) and two-component (PDA and DMPS) (DMPS-PDA-OACF) functionalized activated carbon fibers pretreated by hydrogen peroxide for the removal of trace heavy metals. The as-prepared DMPS-OACF (7.5,20) under DMPS addition of 7.5 mg and sonication time of 20 min retained large specific surface area, micro-mesoporous structure and rich functional groups and showed better adsorption performance for trace lead and mercury. It also exhibited wide applicable ranges of pH (3.50-10.50) and concentration (50-1136 μg L^-1), rapid adsorption kinetics, and excellently selective removal performance for trace lead. The maximum lead adsorption capacity reached 16.03 mg g^-1 when the effluent lead concentration met World Health Organization (WHO) standard and the adsorbent can be regenerated by EDTA solution. The fitting results of adsorption kinetics and isotherm models revealed that the lead adsorption process was multi-site adsorption on heterogeneous surfaces and chemical adsorption. The excellent adsorption properties for trace heavy metals were attributed that the sulfur/oxygen/nitrogen-containing functional groups boosted diffusion and adsorption by electrostatic attraction and coordination, suggesting that DMPS-OACF (7.5,20) has great application potential in the removal of trace heavy metals.

Ionic liquid-immobilized silica gel as a new sorbent for solid-phase extraction of heavy metal ions in water samples

In the current study, we have developed a solid-phase extraction (SPE) method with novel C18-alkylimidazolium ionic liquid immobilized silica (SiO₂–(CH₂)₃–Im–C₁₈) for the preconcentration of trace heavy metals from aqueous samples as a prior step to their determination by inductively coupled plasma mass spectrometry (ICPMS). The material was characterized by Fourier-transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), Energy-Dispersive X-ray Spectroscopy (EDS), and Brunauer–Emmett–Teller (BET) analysis. A mini-column packed with SiO₂–(CH₂)₃–Im–C₁₈ sorbent was used for the extraction of the metal ions complexed with 1-(2-pyridylazo)-2-naphthol (PAN) from the water sample. The effects of pH, PAN concentration, length of the alkyl chain of the ionic liquid, eluent concentration, eluent volume, and breakthrough volume have been investigated. The SiO₂–(CH₂)₃–Im–C₁₈ allows the isolation and preconcentration of the heavy metal ions with enrichment factors of 150, 60, 80, 80, and 150 for Cr³⁺, Ni²⁺, Cu²⁺, Cd²⁺, and Pb²⁺, respectively. The limits of detection (LODs) for Cr³⁺, Ni²⁺, Cu²⁺, Cd²⁺, and Pb²⁺ were 0.724, 11.329, 4.571, 0.112, and 0.819 μg L⁻¹, respectively with the relative standard deviation (RSD) in the range of 0.941–1.351%.

Novel C18-alkylimidazolium ionic liquid immobilized silica (SiO₂–(CH₂)₃–Im–C₁₈) was synthesized through a four-step procedure. It showed high efficiency for the separation/preconcentration of trace heavy metal ions from aqueous samples.

Adsorption of Methylene Blue on Azo Dye Wastewater by Molybdenum Disulfide Nanomaterials

In this study, flower-like MoS2 nanomaterials were synthesized by hydrothermal method with excess thiourea. The adsorption performance of MoS2 adsorbent for methylene blue (MB) in azo dye wastewater was studied. The morphology, crystal phase, and microstructure of nano MoS2 samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The effects of adsorption isotherm, kinetics, different hydrothermal time, and pH on the adsorption experiment were studied. The results showed that the MoS2 adsorbent with a hydrothermal time of 1 h had good adsorption properties for MB. The adsorption data accord with the Langmuir isotherm model, and the maximum adsorption capacity of MoS2 adsorbent is 200 mg/g, and the adsorption kinetics agrees well with the pseudo two-level model. The removal rate of MB is not significantly affected by the pH values. The large pH range can still maintain the removal rate above 93.47%, and the regeneration and recovery properties of MoS2 were also explored. Finally, the adsorption mechanism of MoS2 on MB is discussed.

Thermodynamics and Mechanism of the Adsorption of Heavy Metal Ions on Keratin Biomasses for Wastewater Detoxification

The analysis of thermodynamics and mechanism of the adsorption of cadmium, chromium, copper, and lead ions from aqueous solution with two keratin-based biomaterials, namely, human hair and sheep fur, is reported in this paper. The effect of initial ion concentration, temperature, pH, contact time, and biomaterial amount on the removal of these heavy metal ions using these keratinous adsorbents was studied. The adsorption of heavy metal ions was highly dependent on the operating parameters where pH and temperature showed the highest impact. Maximum adsorption capacities of these biomaterials were up to 1.33 and 1.40 mmol/g for chromium ions using human hair and sheep fur, respectively. Adsorption kinetic rates of tested heavy metal ions were calculated via a pseudo-second-order model, and they ranged from 0.054 to 0.261 g/mmol·min. A detailed thermodynamic analysis of lead ion adsorption was performed showing an endothermic removal of this adsorbate with both human hair and sheep fur with adsorption enthalpies of 84.5 and 97.1 kJ/mol, respectively. Statistical physics calculations demonstrated that this heavy metal ion was adsorbed via a multi-interaction mechanism especially for human hair. These keratinous biomaterials showed competitive adsorption capacities especially for chromium ion removal and can outperform commercial activated carbons and other adsorbents reported in literature.

Synergetic degradation of Methylene Blue through photocatalysis and Fenton reaction on two-dimensional molybdenite-Fe

The greatest problem in conventional Fenton reaction is the slow production of ROS (reactive oxygen species) because of the inefficient Fe³⁺/Fe²⁺ conversion. Based on the extraordinary photo-response property of two-dimensional molybdenite (2DM), photogenerated electrons can be easy separated to accelerate the regeneration of Fe²⁺. In this work, Fe²⁺-anchored 2DM (2DM-Fe) was prepared and used as a heterogeneous Fenton catalyst to investigate the degradation efficiency to Methylene Blue (MB) in the presence of light. According to experimental results, 2DM-Fe exhibited extraordinary catalytic activity in MB elimination, which ascribed to the synergetic effect of photogenerated carriers and anchored Fe²⁺ to H₂O₂ activation. In addition, 2DM-Fe showed nearly 100% degradation efficiency to MB within 5 cycles with slight leaching amount of Mo and Fe ions, implying the strong stability and reusability in H₂O₂ system. Furthermore, the influences of H₂O₂ and 2DM-Fe dosages, pH values as well as the degradation efficiency to different dyes were also investigated. According to quenching experiments and EPR (electron paramagnetic resonance) test, the degradation mechanism of MB mainly ascribed to the oxidation of HO• and •O₂^-. This finding provides a novel strategy to design rational Fenton catalyst and has great significance to water remediation in the future.

Molybdenum disulfide-graphene oxide composites as dispersive solid-phase extraction adsorbents for the enrichment of four paraben preservatives in cosmetics

Molybdenum disulfide-graphene oxide composite (MoS₂/GO) was synthesized and used as the adsorbent in dispersive solid-phase extraction. Four paraben preservatives, namely, methylparaben, ethylparaben, propylparaben, and butylparaben, were enriched with MoS₂/GO and determined by ultra-high-performance liquid chromatography. Molybdenum disulfide was intercalated into graphene oxide layers to reduce self-aggregation by using the solvothermal method. The experimental results indicated that the as-prepared MoS₂/GO composite exhibited great enrichment capability toward those four paraben preservatives, and the adsorption time was 10 min and the elution time was as short as 1 min. The mechanism of MoS₂/GO composite and parabens is attributed to hydrogen bonding and electrostatic attraction. The relative standard deviation (RSD, n = 9) of this method was below 7.6%. Limits of detection and limits of quantification were in the range 0.4-2.3 ng/mL and 1.4-7.6 ng/mL, respectively. The recoveries obtained from the parabens of cosmetic sample were in the range 91.3-124% with RSDs below 10%. The developed method has great potential for the determination of emerging contaminants with low cost and high sensitivity.

Aqueous Adsorption of Heavy Metals on Metal Sulfide Nanomaterials: Synthesis and Application

Heavy metals pollution of aqueous solutions generates considerable concerns as they adversely impact the environment and health of humans. Among the remediation technologies, adsorption with metal sulfide nanomaterials has proven to be a promising strategy due to their cost-effective, environmentally friendly, surface modulational, and amenable properties. Their excellent adsorption characteristics are attributed to the inherently exposed sulfur atoms that interact with heavy metals through various processes. This work presents a comprehensive overview of the sequestration of heavy metals from water using metal sulfide nanomaterials. The common methods of synthesis, the structures, and the supports for metal sulfide nano-adsorbents are accentuated. The adsorption mechanisms and governing conditions and parameters are stressed. Practical heavy metal remediation application in aqueous media using metal sulfide nanomaterials is highlighted, and the existing research gaps are underscored.

Adsorptive Removal of Cd(II) Ions from Wastewater Using Maleic Anhydride Nanocellulose

In this study, both pristine cellulose nanocrystalline (CNC) and maleic anhydride functionalized cellulose nanocrystalline (MA-CNC) were prepared from the stems of Eichhornia crassipes weed by the sulfuric acid hydrolysis method. The as-prepared adsorbents were characterized by using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) instruments. These materials were applied for the removal of Cd(II) ions from WW. The uptake mechanism was fixed to both Langmuir and Freundlich adsorption isotherms with a maximum Cd(II) ion uptake capability (qmax) of 75.76 and 215.52 mg g−1 by CNC and MA-CNC adsorbents, respectively. Pseudo-second-order (PSO) kinetic model was well fitted to the uptake process. The adsorbent regeneration study was done after desorption of Cd(II) ions from the adsorbent by HCl washing. Results exhibited that the adsorbent was reused for the removal of Cd(II) ions from real WW after successive 13th cycle.

Graphene-Based Macromolecular Assemblies for Scavenging Heavy Metals

The integration of graphene or graphene oxide nanosheets into three-dimensional (3D) graphene-based macromolecular assemblies (GMAs), in the form of sponges, beads, fibres, films, and crumpled nanosheets, has greatly advanced their environmental remediation applications. This is attributed to the outstanding physicochemical characteristics and superlative mechanical features of 3D GMAs, including precise and physically linked permeable networks, enormous surface area, profound porosity, and high-class sturdiness, amongst others. In this review, the recent advancements towards the exploration of 3D GMAs as an exciting new class of high-performance adsorbents, for eliminating toxic heavy metal ions from both wastewater and freshwater, are systematically summarized and discussed, from both fundamental and applied perspectives. In particular, the numerous surface modification techniques that are actively pursued to enrich the metal adsorption capacity of 3D GMAs, are comprehensively examined. Additionally, associated challenges are pointed out and tactical research strategies and improvements are proposed, with an eye on the conceivable future.

Bacterial Nanocellulose/MoS2 Hybrid Aerogels as Bifunctional Adsorbent/Photocatalyst Membranes for in-Flow Water Decontamination

To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS₂), in particular, we report the preparation of self-supported hybrid aerogel membranes that combine the mechanical stability and excellent textural properties of bacterial nanocellulose (BC)-based organic macro/mesoporous scaffolds with the excellent adsorption-cum-photocatalytic properties and high contaminant removal performance of MoS₂ nanostructures. A controlled hydrothermal growth and precise tuning of the synthetic parameters allowed us to obtain BC/MoS₂-based porous, self-supported, and stable hybrid aerogels with a unique morphology resulting from a molecular precision in the coating of quantum-confined photocatalytic MoS₂ nanostructures (2-4 nm crystallite size) on BC nanofibrils. These BC/MoS₂ samples exhibit high surface area (97-137 m²·g^-1) and pore volume (0.28-0.36 cm³·g^-1) and controlled interlayer distances (0.62-1.05 nm) in the MoS₂ nanostructures. Modification of BC with nanostructured MoS₂ led to an enhanced pollutants removal efficiency of the hybrid aerogels both by adsorptive and photocatalytic mechanisms, as indicated by a detailed study using a specifically designed membrane photoreactor containing the developed photoactive/adsorptive BC/MoS₂ hybrid membranes. Most importantly, the prepared BC/MoS₂ aerogel membranes showed high performance in the photoassisted in-flow removal of both organic dye (methylene blue (MB)) molecules (96% removal within 120 min, K_obs = 0.0267 min^-1) and heavy metal ions (88% Cr(VI) removal within 120 min, K_obs = 0.0012 min^-1), separately and/or simultaneously, under UV-visible light illumination as well as excellent recyclability and photostability. Samples with interlayer expanded MoS₂ nanostructures were particularly more efficient in the removal of smaller species (CrO₄^2-) as compared to larger (MB) dye molecules. The prepared hybrid aerogel membranes show promising behavior for application in in-flow water purification, representing a significant advancement in the use of self-supported aerogel membranes for photocatalytic applications in liquid media.

Facile Preparation of Three-Dimensional MoS2 Aerogels for Highly Efficient Solar Desalination

Aerogels, with porous channels for water supply and vapor escape, can provide many inherent advantages in solar desalination and wastewater treatment. For the first time, this work demonstrates the preparation of a novel three-dimensional (3D) MoS₂-based aerogel with high porosity and mechanical stability by a facile strategy for solar desalination. This 3D MoS₂ aerogel has an excellent light-absorbing efficiency of over 95% within the whole solar spectrum range, enabling a high evaporation efficiency of 88.0% under a low solar irradiation of 1.0 kW m^-2 and superhigh evaporation efficiencies of over 90% under a slightly enhanced solar irradiation of 1.5-3.0 kW m^-2 as well as a remarkable desalination performance. In addition, the excellent mechanical stability of this MoS₂ aerogel renders it to be reused for at least 10 cycles with stable water productivity. Because of its 3D architectures with high porosity and easy separation, this MoS₂-based aerogel also provides promising applications in solar-driven water purification, sterilization, and so forth.

Multi-edged molybdenite achieved by thermal modification for enhancing Pb(II) adsorption in aqueous solutions

Thermal modification was simply performed on molybdenite to enhance the adsorption of Pb(II) in aqueous solutions, and the root of this phenomenon was well studied in this work. Various thermal modification temperatures at 300 °C, 400 °C and 500 °C were applied to modify the surface property of molybdenite, producing different degrees of edge defect and surface wettability in molybdenite samples. Contact angle tests, atomic force microscopy (AFM) observations and adsorption tests illustrated that molybdenite thermally modified at 400 °C contained most edge defects and achieved a 147.846 mg/g Pb(II) adsorption, which was almost 10 times of that obtained by natural molybdenite. The adsorption experiment also indicated that the increase of surface hydrophilia of molybdenite would slightly benefit the Pb(II) adsorption. The X-ray photoelectron spectroscope (XPS) exhibited that a strong chemical adsorption existed between Pb(II) and S elements. AFM study further demonstrated that the interaction between Pb(II) and S atoms exposed at the triangular edges of molybdenite were the intrinsic reason for the great enhancement of Pb(II) adsorption. This work provides a new insight to absorb Pb(II) in aqueous solutions using natural molybdenite.

Tunable Molybdenum Disulfide-Enabled Fiber Mats for High-Efficiency Removal of Mercury from Water

The application of molybdenum disulfide (MoS₂) for water decontamination is expanded toward a novel approach for mercury removal using nanofibrous mats coated with MoS₂. A bottom-up synthesis method for growing MoS₂ on carbon nanofibers was employed to maximize the nanocomposite decontamination potential while minimizing the release of the nanomaterial to treated water. First, a co-polymer of polyacrylonitrile and polystyrene was electrospun as nanofibrous mats and pretreated to form pristine carbon fibers. Next, three solvothermal methods of controlled in situ MoS₂ growth of different morphologies were achieved on the surface of the fibers using three different sets of precursors. Finally, these MoS₂-enabled fibers were extensively characterized and evaluated for their mercuric removal efficiency. Two mercury removal mechanisms, including reduction-oxidation reactions and physicochemical adsorption, were elucidated. The two nanocomposites with the fastest (0.436 min^-1 mg^-1) and highest mercury removal (6258.7 mg g^-1) were then further optimized through intercalation with poly(vinylpyrrolidone), which increased the MoS₂ interlayer distance from 0.68 nm to more than 0.90 nm. The final, optimal fabrication technique (evaluated according to mercuric capacity, kinetics, and nanocomposite stability) demonstrated five times higher adsorption than the second-best method and obtained 70% of the theoretical mercury adsorption capacity of MoS₂. Overall, results from this study indicate an alternative, advanced material to increase the efficiency of aqueous mercury removal while also providing the basis for other novel environmental applications such as selective sensing, disinfection, and photocatalysis.

Rhizoremediation of Cu(II) ions from contaminated soil using plant growth promoting bacteria: an outlook on pyrolysis conditions on plant residues for methylene orange dye biosorption

Rhizoremediation is one of the most accepted, cost-effective bioremediation techniques focusing on the application of rhizospheric microorganisms in combination with plants for the remediation of organic and inorganic pollutants from the contaminated sites. This work focuses on isolation and identification of metal resistant bacteria to grow on medium with the copper ion concentration of 1500 mg/L. The resistant isolate was identified as Pantoea dispersa by a 16S rRNA sequencing. The bioaccumulation of Cu(II) ions in plant is high at the concentration of Cu(II) ion is 125 mg/L in soil. In Sphaeranthus indicus the Cu(II) ion translocation factor has expanded with an expansion of grouping of Cu(II) ion in the soil and the most extreme TF factor was acquired at the centralization of Cu(II) ion is 150 mg/L in soil. Surface morphology of biochar was characterized by Scanning Electron Microscopy (SEM) analysis. The adsorption performance of biochar (Sphaeranthus indicus biomass) and mechanism for the removal of Cu(II) ion were investigated. This study resolves that pyrolysis is promising technology for the conversion of metal ion contaminated plant residues from phytoremediation into valuable products.