Materials For Heavy Metal Ions Research Articles

Synthesis of mixed-base active material from drilling fluid solid waste and biomass for oil wastewater adsorption and its mechanism

To address the issues of high energy consumption, high cost and the risk of secondary pollution in drilling fluid solid waste treatment methods, this study prepared a mixed-based active material using drilling fluid solid waste and biomass materials as raw materials. The mixed-based active material is characterized by its abundant pore structure and high pore volume, demonstrating excellent adsorption performance for heavy metal ions and residual oil in industrial wastewater. Thermogravimetric and basic physical property analyses indicated a synergistic effect between drilling fluid solid waste and biomass materials, showing that joint pyrolysis of the two can enhance the yield of active materials. The adsorption performance of mixed-base active materials for heavy metal ions and residual oil were was tested. It was found that the removal rate of four heavy metal ions (Cr6+, Mn2+, Cu2+, and Zn2+) from the solution could reached 57.1 %, 96.3 %, 99.0 % and 94.1 %, respectively, at a concentration of 0.5 g/L of mixed-base active materials. Characterization revealed that the mixed-base activated carbon has a well-developed pore structure and numerous types of functional groups. The isothermal adsorption process of heavy metal ions by the active material is consistent with the Langmuir model and belongs to the monomolecular layer adsorption. The adsorption rate model of residual oil in wastewater by active materials conforms to the pseudo-second-order equation. The adsorption performance of mixed-base active materials primarily stems from physical adsorption enabled by their well-developed internal pore structure, along with chemical adsorption facilitated by oxygen- and nitrogen-containing functional groups on the surface.

Two-dimensional layered MOF nanosheets with multiple binding sites for selective detection and removal of Fe(III) ions

Heavy metal contamination has become an urgent global concern, posing a significant threat to our environment and health. Hence, it is critical to exploit functional materials for heavy metal ions sensing and elimination. However, the development of multifunctional materials that can simultaneously accomplish the selective detection and removal of the metal ions remains a significant challenge. In this work, a two-dimensional (2D) layered metal–organic framework (LMOF) functionalized with diverse binding sites has been utilized to concurrently detect and remove Fe3+ ions. The LMOF [Zn(hsb-2) (5-aipa)](HSB-W15) was rationally designed and constructed from the mixed ligands of hsb-2 (1,2-bis(4′-pyridylmethylamino)-ethane) and 5-aipa (5-aminoisophthate) under mild condition. In addition, the corresponding ultrathin nanosheets HSB-W15-NS were also obtained by adapting the instant in situ exfoliation (IISEM) method. Owing to the ultrathin nanosheet morphology and an abundance of active sites on the surface, HSB-W15-NS nanosheets can function as an effective fluorescent sensor to detect Fe3+ and Cr3+ ions. Exceptionally, HSB-W15-NS can also be used to selectively capture Fe3+ ions from water, with up to 93 % removal efficiency, and the adsorption equilibrium attained in 5 min. The sensing and adsorption processes were investigated based on kinetic model analysis, Fourier transform infrared spectroscopy, Raman spectrum analysis, density functional theory calculations, and control experiments. This work inspired the development of ultrathin 2D MOF nanosheets for applications in environmental protection.

Adsorption of Pb, Cu and Cd from Water on Coal Fly Ash-Red Mud Modified Composite Material: Characterization and Mechanism

The rational utilization of solid waste has always been a worldwide concern. In this study, coal fly ash (CFA) and red mud (RM) were used in combination to synthesize efficient heavy metal adsorbents. A new way of resource recycling was provided with the collaborative reuse of CFA and RM. To obtain the modified composite materials, CFA and RM were mixed and melted in three ratios. After modification, these materials were then utilized to adsorb Pb, Cu, and Cd in water in both single and ternary systems. The physicochemical properties of CFA, RM, and three modified composite materials were measured by X-ray diffraction analysis, energy dispersive X-ray spectroscopy, scanning electron microscope, Fourier transform infrared spectroscopy, vibrating sample magnetometer, surface area analyzer, and porosity analyzer. In the single and ternary systems, the effects of the modified composite material dosage, solution pH, initial concentration of heavy metals, and adsorption time were discussed, and the results were better fitted with the Langmuir isotherm and the pseudo-second-order kinetic. It was discovered that the modified composite materials had a greater specific surface area (63.83 m2/g) than CFA and RM alone, as well as superior adsorption capacity and magnetic characteristics. The adsorption capacities of C1R4 for Pb, Cu, and Cd were 149.81 mg/g, 135.96 mg/g, and 127.82 mg/g in the single system, while those of Cu and Cd decreased slightly in the ternary system, and the preferential adsorption order of the modified composite materials for heavy metal ions was Pb > Cu > Cd. Among the three modified composite materials, C1R4 had the best adsorption capacity.

A composite of carbon nanofiber/copper particle-anchored thiol-incorporated silica nanoparticles utilizable for heavy metal adsorption

We report a design and synthesis of a composite comprised of carbon nanofiber (CNF) and Cu particles which thiol-incorporated silica particles are surface-bound. The CNFs bearing homogeneously distributed Cu particles were fabricated via electrospinning of Cu2+/polymer solution and subsequent pyrolysis for carbonization. Thiol-incorporated silica nanoparticles (T-Sil) were synthesized via a modified Stöber method and attached to the surface of Cu particles by a simple immersion process to result in T-Sil anchored Cu particle-embedded CNF (T-Sil/Cu–CNF). The morphology of the resulting composite and the formation of Cu particles in the CNF were thoroughly examined and further utilized as an adsorbent material for heavy metal ions of Ni2+ and Cu2+ in water. The chemical route not only opened the potential of CNF-based composite materials for water remediation applications, but also provided the possibility for CNF material functionalization without structural damage which is beneficial toward expanding its applicability in complex composite materials.

Pyrene-functionalized mesoporous silica as a fluorescent nanosensor for selective detection of Hg2+ in aqueous solution

Selective detection of Hg2+ is in high demand as Hg2+ can cause serious environmental problems and harmful diseases. In the present work, a pyrene- functionalized organic-inorganic hybrid nanosensor was synthesized by using mesoporous silica nanoparticles as scaffold and pyrene unit as signal output, which could realize selective turn-off detection of Hg2+ in aqueous solution. The successful synthesis of the pyrene-functionalized fluorescent nanoparticle was demonstrated by a series of characterization methods including TEM, BET-BJH, FT-IR, TGA, XPS and solid-state 13C NMR. Some measurements also indicated that there could be a grafting process on both the surface of mesoporous silica nanoparticles and the interior of mesopores. The fluorescence measurements showed that the fluorescent nanosensor exhibited selective turn-off responses to Hg2+ over a series of 15 other metal ions, and the selective detection was hardly interfered by the presence of these interfering metal ions even at 10 equiv. amount. Moreover, the nanosensor could semi-quantitatively detect Hg2+ over a concentration range from 1 to 20 μM with a detection limit of 0.62 μM. Time-resolved fluorescence measurements and 1H NMR titration indicated the binding of Hg2+ with the spacer contributed to the selective responses to Hg2+. The obtained pyrene-functionalized mesoporous silica nanoparticles illustrated high sensitivity, high selectivity and reliability in detecting Hg2+, contributing to the development of organic-inorganic hybrid materials for heavy metal ions.

Engineering Co2+/Co3+ redox activity of Ni-mediated porous Co3O4 nanosheets for superior Hg(II) electrochemical sensing: Insight into the effect of valence change cycle and oxygen vacancy on electroanalysis

Transition metal oxides (TMOs) have been recognized as promising sensing materials for heavy metal ions (HMIs) detection, mainly ascribing to a strong adsorption of HMIs on surface oxygen vacancies (OVs) of TMOs. However, the possibly more prominent role of valence change induced redox activity of TMOs in HMIs detection has not received its deserved attention, thus severely hindering the further development of TMOs-based HMIs detection. Herein, a facile strategy is proposed to co-engineer the redox activity and surface OVs of porous Co3O4 nanosheets by Ni doping. As a result, a boosted redox activity and an enhanced adsorption have been simultaneously achieved by optimizing the Ni doping level. Specifically, the 5% (atomic ratio) Ni-doped Co3O4 nanosheets exhibited best electroanalytical performance towards toxic Hg(II). More importantly, it has been demonstrated that the valence change cycle of Co cations (Co2+/Co3+) plays a more important role in electrochemical detection, rather than the adsorption of Hg(II) on OVs. Namely, the reduction of Hg(II) to Hg(0) on Co3O4 nanosheets can be effectively promoted by Ni-doping facilitated valence change cycle of Co cations (Co2+/Co3+). This work provides a feasible way to develop TMOs-based sensing materials by energetically synergizing their redox activity and adsorption ability towards HMIs simultaneously.

Quantum dot (QD)-based probes for multiplexed determination of heavy metal ions.

Heavy metal contamination is a major global concern and additive toxicity resulting from the exposure to multiple heavy metal ions is more pronounced than that induced by a single metal species. Quantum dots (QDs) have demonstrated unique properties as sensing materials for heavy metal ions over the past two decades. With the rapid development and deep understanding on determination of single heavy metal ion using QD probes, this technology has been employed for sensing multiple metal ions. This review (with 97 refs.) summarizes the progress made in recent years in methods for multiplexed determination of heavy metal ions using QDs. Following an introduction into the importance of simultaneous quantitation of multiple heavy metal ions in environmentally relevant settings, the review discusses the applications of different types of QDs, i.e. chalcogenide, carbon, polymer and graphene in this field. Determination strategies based on fluorometric, colorimetric and electrochemical responses were reviewed including the testing mechanisms and differentiation between various metal ions. In addition, current state of the art sensor constructions, i.e. immobilization of QDs on solid substrate and sensor arrays have been highlighted. A concluding section describes the limitations, opportunities and future challenges of the QD probes. We also compiled a comprehensive table of currently available literature. The listed papers provided information in the following categories, i.e. type of QDs used, ligands or other components in the probe, metal ions tested, medium/substrate of the probe, transduction methods, discrimination mechanism, limit of detection (LOD) and concentration range. Graphic abstract.

(Super)paramagnetic nanoparticles as platform materials for environmental applications: From synthesis to demonstration

Over the past few decades, engineered, (super)paramagnetic nanoparticles have drawn extensive research attention for a broad range of applications based on their tunable size and shape, surface chemistries, and magnetic properties. This review summaries our recent work on the synthesis, surface modification, and environmental application of (super)paramagnetic nanoparticles. By utilizing hightemperature thermo-decomposition methods, first, we have broadly demonstrated the synthesis of highly monodispersed, (super)paramagnetic nanoparticles, via the pyrolysis of metal carboxylate salts in an organic phase. Highly uniform magnetic nanoparticles with various size, composition, and shape can be precisely tuned by controlled reaction parameters, such as the initial precursors, heating rate, final reaction temperature, reaction time, and the additives. These materials can be further rendered water stable via functionalization with surface mono/bi-layer coating structure using a series of tunable ionic/non-ionic surfactants. Finally, we have demonstrated platform potential of these materials for heavy metal ions sensing, sorption, and separation from the aqueous phase.

Investigation on the Adsorption-Interaction Mechanism of Pb(II) at Surface of Silk Fibroin Protein-Derived Hybrid Nanoflower Adsorbent.

For further the understanding of the adsorption mechanism of heavy metal ions on the surface of protein-inorganic hybrid nanoflowers, a novel protein-derived hybrid nanoflower was prepared to investigate the adsorption behavior and reveal the function of organic and inorganic parts on the surface of nanoflowers in the adsorption process in this study. Silk fibroin (SF)-derived and copper-based protein-inorganic hybrid nanoflowers of SF@Cu-NFs were prepared through self-assembly. The product was characterized and applied to adsorption of heavy metal ion of Pb(II). With Chinese peony flower-like morphology, the prepared SF@Cu-NFs showed ordered three-dimensional structure and exhibited excellent efficiency for Pb(II) removal. On one hand, the adsorption performance of SF@Cu-HNFs for Pb(II) removal was evaluated through systematical thermodynamic and adsorption kinetics investigation. The good fittings of Langmuir and pseudo-second-order models indicated the monolayer adsorption and high capacity of about 2000 mg g−1 of Pb(II) on SF@Cu-NFs. Meanwhile, the negative values of and proved the spontaneous and exothermic process of Pb(II) adsorption. On the other hand, the adsorption mechanism of SF@Cu-HNFs for Pb(II) removal was revealed with respect to its individual organic and inorganic component. Organic SF protein was designated as responsible ‘stamen’ adsorption site for fast adsorption of Pb(II), which was originated from multiple coordinative interaction by numerous amide groups; inorganic Cu3(PO4)2 crystal was designated as responsible ‘petal’ adsorption site for slow adsorption of Pb(II), which was restricted from weak coordinative interaction by strong ion bond of Cu(II). With only about 10% weight content, SF protein was proven to play a key factor for SF@Cu-HNFs formation and have a significant effect on Pb(II) treatment. By fabricating SF@Cu-HNFs hybrid nanoflowers derived from SF protein, this work not only successfully provides insights on its adsorption performance and interaction mechanism for Pb(II) removal, but also provides a new idea for the preparation of adsorption materials for heavy metal ions in environmental sewage in the future.

Review—Recent Advances in Nanostructured Graphitic Carbon Nitride as a Sensing Material for Heavy Metal Ions

Graphitic carbon nitride (g-C3N4), as a crucial sensing material has attracted intense interest for sensor devices development. Owing to its large specific surface area, excellent physicochemical stability, exceptional electronic band structure, and outstanding electronic, thermal, optical, and mechanical properties. In addition, excellent biocompatibility, unique electroluminescent and photoelectrochemical properties, g-C3N4 nanomaterials contribute to the development of fast, accurate, cost-effective, and reliable sensors. Herein, we provide a comprehensive review on the development of g-C3N4 nanomaterials-based sensors and their potential detection applications for various heavy metal analytes. Furthermore, a comparative sensing performance of sensors, current challenges and prospective of g-C3N4 based nanomaterials are outlined in detail.

Double-shelled yolk-shell Si@C microspheres based electrochemical sensor for determination of cadmium and lead ions

In this work, we report double-shelled yolk-shell Si@C structure as a high-performance electrochemical sensing material for heavy metal ions. A SiO2-assisted polybenzoxazine (PB) coating strategy is used to synthesize highly monodispersed Si@C microspheres. After thermal carbonization of PB layers and selective removal of the SiO2 layers, Si@C microspheres were prepared. The resultant Si@C microspheres exhibit uniform spherical morphology and clearly double-shelled yolk-shell structures. The obtained Si@C microspheres are employed to prepare the chemically modified electrode for the sensitive determination of Cd(II) and Pb(II). By the method of anodic stripping voltammetry, the Si@C-based electrode shows a very wide linear dynamic range for target ions (e.g., 0.5–400 μg L−1 for Cd(II) and Pb(II)) and low limit of detections (e.g., 0.068 μg L−1 for Cd(II) and for 0.105 μg L−1 Pb(II)). The remarkable results, such as excellent resistance to interference ions, good repeatability, and reproducibility were also obtained. Furthermore, compared with those Cd(II) and Pb(II) sensors known in the literature, the analytical performance of Si@C-based electrode is better. Finally, when further used to determine Cd(II) and Pb(II) in tap water and lake water, the results of fabricated electrode successfully achieve good consistency with the data obtained from inductively coupled plasma-mass spectrometry (ICP-MS).

Facile Hydrothermal Preparation of Carboxymethyl Chitosan Functionalized Hydrotalcite Composite with Enhanced Adsorption Capacity for Cu(II) Ions.

In order to enhance the adsorption capacity of hydrotalcite material for heavy metal ions, the LDH/CMC composite was prepared by a simple hydrothermal method. The XRD pattern showed that the presence of CMC has no obvious influence on the crystal structure of hydrotalcites. The FT-IR and UV-vis DRS analyses showed that the CMC functionalized surface has been obtained. The SEM and BET/BJH showed that the morphologies, textural and surface chemical properties of LDH were affected remarkably after the introduction of CMC. The weight percentage of CMC in the LDH/CMC composite was estimated to be about 17.4%. The adsorption experiments showed the LDH/CMC composite exhibited high efficiency in the Cu(II) removal at pH > 6.5, affording Cu(II) removal rates of 92.3%. The results demonstrated that the LDH/CMC composite was a suitable adsorbent for Cu(II)-contaminated wastewater treatment.

Removal of Heavy Metals Using Nanostructured Graphite Oxide, Silica Nanoparticles and Silica/ Graphite Oxide Composite

Heavy metals are known to be toxic for living organisms even if they are present at low levels. The presence of heavy metals and other pollutants in water continues to be a major concern and the removal of such contaminant is considered to be a major problem in environmental remediation. In the present study, nanostructured graphite oxide, silica/graphite oxide composites and silica nanoparticles were used for the removal of the heavy metal ions from aqueous solutions by a batch adsorption method and have been modelled using classical Langmuir and Freundlich adsorption isotherms. The results revealed that the adsorption of heavy metals by nanostructured graphite oxide was observed in the following order: nickel > zinc > lead > cadmium > chromium. Langmuir adsorption isotherm results showed that graphite oxide is an effective adsorbent for the removal of Nickel ions from aqueous solutions, while Freundlich data obtained for Cadmium, Chromium, Lead, Nickel and Zinc ions suggest monolayer type of adsorption by graphite oxide. Results showed that silica/graphite oxide composite (2:3) is a highly effective adsorbent material for heavy metal ions and highly recommended to be used in water purification technologies.