A review on recent advancements on removal of harmful metal/metal ions using graphene oxide: Experimental and theoretical approaches

Remediation of Safranin-O and Acid Fuchsin by Using Ti3C2 MXene /rGo-Cu2O Nanocomposite: Preparation, Characterization, Isotherm, Kinetics and Thermodynamic Studies

In recent years, MXene has become one of the most intriguing two-dimensional layered (2Dl) materials extensively explored for various applications. In this study, a Ti3C2 MXene/rGo-Cu2O Nanocomposite (TGCNCs) was developed to eliminate Safranin-O effectively (SO) and Acid Fuchsin (AF) as cationic dyes from the aquatic environment. Multistep was involved in the preparation of the adsorbent system, including the Preparation of Ti3C2, after that, GO synthesis by the Humer method, followed by rGO production, then added CuSO4 to obtain a final Nanocomposite (NCs) called "TGCNCs". The structure of TGCNCs can be varied in several ways, including FTIR, SEM, TGA, Zeta, EDX, XRD, and BET, to affirm the efficacious preparation of TGCNCs. A novel adsorbent system was developed to remove SO and AF, both cationic dyes. Various adsorption conditions have been optimized through batch adsorption tests, including the pH of the solution (4-12), the effect of dosage (0.003-0.03 g), the impact of the contact time (5-30 min), and the effect of beginning dye concentration (25-250 mg/L). Accordingly, the TGCNCs exhibited excellent fitting for Freundlich isotherm mode, resulting in maximum AF and SO adsorption capacities of 909.09 and 769.23 mg.g-1. This research on adsorption kinetics suggests that a pseudo-second-order (PSO) model would fit well with the experimental data ( = 0.998 and = 0.990). It is evident from the thermodynamic parameters that adsorption is an endothermic process that is spontaneous and favourable. During the adsorption of SO and AF onto NCs, it is hypothesized that these molecules interact intramolecularly through stacking interactions, H-bond interactions, electrostatic interactions, and entrapment within the polymeric Poros structure nanocomposite. Regeneration studies lasting up to five cycles were the most effective for both organic dyes under study.

Preparation of 4-Amino-3-hydrazino-1,2,4-triazol-5-thiol-Modified Graphene Oxide and Its Greatly Enhanced Selective Adsorption of Gallium in Aqueous Solution

Efficient recovery of gallium (Ga) from vanadium slag processing residue (VSPR) solution is of great significance for environmental protection and resource utilization, but improving its selective adsorption against the coexisting Sc3+ and In3+ is still challenging. Herein, a novel adsorbent consisting of 4-amino-3-hydrazino-1,2,4-triazol-5-thiol (AHTZT)-modified graphene oxide (GO-AHTZT) was successfully synthesized that exhibits a higher adsorption selectivity for Ga3+ in VSPR solution with coexisting Sc3+ and In3+. Under optimal conditions, the adsorption capacity of GO-AHTZT for Ga3+ can reach 23.92 mg g-1, which is 4.9 and 12.6 times higher than that for Sc3+ (4.87 mg g-1) and In3+ (1.90 mg g-1) adsorption, indicating the excellent anti-interference ability of GO-AHTZT against Sc3+ and In3+. The process and mechanism of Ga3+ adsorption onto GO-AHTZT was also studied and discussed in detail. By measuring the adsorption process and by characterizing the adsorbent before and after adsorption, we demonstrate that the selective interaction between the Ga3+- and N-containing groups in AHTZT is the main reason for the improved adsorption selectivity. This work opens up an avenue for the design and synthesis of highly selective adsorbents for Ga3+ in complex VSPR solutions.

Facile hydrothermal assembly of three-dimensional GO-MTZE composite and its adsorption properties toward Cu2

Three-dimensional (3D) graphene oxide (GO)-based aerogels, GO and 4-methyl-5-thiazoleethanol (MTZE) composites, were prepared by a facile hydrothermal method. Due to the hydrogen bonding and π-π stacking interactions, the produced 3D GO-MTZE composites possessed large cylindrical structures. The morphologies, composition, and chemical states of 3D GO-MTZE3:1 composite were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and N2 adsorption-desorption isotherms based on the Brunauer-Emmett-Teller (BET) method. The existence of nitrogen (N)-containing heterocyclic system and oxygen (O)-containing branched chain of MTZE contributed to the formation of 3D structures, while the complexation effect of heterocyclic sulfur (S)- and N-containing functional groups of MTZE for metal cations dominated the adsorption performance of 3D GO-MTZE3:1 composite, which could selectively adsorb copper ions (Cu2+). In addition, the better hydrophobic property of 3D GO-MTZE3:1 composite facilitates its facile recycling from aqueous solution after adsorption. The adsorption data of 3D GO-MTZE3:1 composite toward Cu2+ fitted well (R2 = 0.9996) with the linear pseudo-second-order kinetic model, giving an equilibrium rate constant (k2) of 0.0187 g mg-1 min-1. The linear Langmuir isothermal model could more accurately describe the experimental data, indicating the adsorption process is mainly dominated by the complexation interactions between MTZE and Cu2+. The thermodynamic parameters of ΔG° (< 0), ΔH° (> 0), and ΔS° (> 0) further indicate that the adsorption is a spontaneous and endothermic, confirming that the complexation between Cu2+ and 3D GO-MTZE3:1 composite occurs. Due to its high selectivity for Cu2+, good hydrophobicity, and excellent stability, the developed 3D GO-MTZE3:1 composite possesses might be promisingly used in the aqueous selective enrichment/removal of Cu2+.

An Updated Review on Functionalized Graphene as Sensitive Materials in Sensing of Pesticides

Numerous chemical pesticides were employed for a long time to manage pests, but their uncontrolled application harmed the health and the environment. Accurately quantifying pesticide residues is essential for risk evaluation and regulatory purposes. Numerous analytical methods have been developed and utilized to achieve sensitive and specific detection of pesticides in intricate sampl es like water, soil, food, and air. Electrochemical sensors based on amperometry, potentiometry, or impedance spectroscopy offer portable, rapid, and sensitive detection suitable for on-site analysis. This study examines the potential of electrochemical sensors for the accurate evaluation of various effects of pesticides. Emphasizing the use of Graphene (GR), Graphene Oxide (GO), Reduced Graphene Oxide (rGO), and Graphdiyne composites, the study highlights their enhanced performance in pesticide sensing by stating the account of many actual sensors that have been made for specific pesticides. Computational studies provide valuable insights into the adsorption kinetics, binding energies, and electronic properties of pesticide-graphene complexes, guiding the design and optimization of graphene-based sensors with improved performance. Furthermore, the discussion extends to the emerging field of biopesticides. While the GR/GO/rGO based sensors hold immense future prospects, and their existing limitations have also been discussed, which need to be solved with future research.

Novel insights into carbon nanomaterials enhancing anammox for nitrogen removal: Effects and mechanisms

Carbon nanomaterials (CNMs) possess the properties including large specific surface area, high porosity, and stable chemical structures, presenting significant application advantages in wastewater treatment. Indeed, CNMs are considered to be added to anammox systems to strengthen anammox function, especially to resolve the challenge of anammox technology, i.e., the slow growth rate of anammox bacteria, as well as its high environmental sensitivity. This paper systematically reviews the promotion effects and mechanisms of CNMs on the nitrogen removal performance of anammox system. Among the zero-, one-, and two-dimensional CNMs, two-dimensional CNMs have best promoting effect on the nitrogen removal performance of anammox system due to its excellent conductivity and abundant functional groups. Then, the promotion effects of CNMs on anammox process are summarized from the perspective of anammox activity and bacteria abundance. Furthermore, CNMs not only enhance the anammox process, but also stimulate the coupling of denitrification pathways with anammox, as well as the improvement of system operational stability (alleviating the inhibitions of low temperature and pH fluctuation), thus contributing to the promoted nitrogen removal performance. Essentially, CNMs are capable of facilitating microbial immobilization and electron transfer, which favor to improve the efficiency and stability of anammox process. Finally, this review highlights the gap in knowledge and future work, aiming to provide a deeper understanding of how CNMs can strengthen the anammox system and provide a novel perspective for the engineering of the anammox process.

Evaluation of the lead and chromium removal capabilities of Bacillus subtilis-induced food waste compost-based biomedia

Food waste compost (FWC) is a sustainable recycling approach employed in soil media, offering extensive advantages to urban areas by promoting resource circulation and effectively managing water pollution. To improve value, Bacillus subtilis (B. subtilis)-induced FWC-based biomedia (BIBMFWCs) was produced via a secondary treatment involving selective meso-thermophilic stages. During the production of BIBMFWCs, physicochemical properties were found to have favorable characteristics for the efficient removal of metal ions. The produced organic-carbonate complex structure demonstrated the synergistic effect involving simultaneous sorption/precipitation mechanisms for the removal of Pb(II) and Cr(III). Also, the dose of B. subtilis has an impact on the pseudo-second-order (PSO) and intra-particle diffusion (IPD) reaction, leading to distinct removal capacities for Pb(II) and Cr(III) [24.26-24.74 mg g-1 in Pb(II) and 12.7-23.93 mg g-1 in Cr(III)]. Furthermore, B. subtilis, an inducing mediator for microbial metabolites, exhibits the potential to facilitate the removal of Pb(II) and Cr(III) through biological modification of raw materials, which are transformed, facilitating the presence of hydroxyl groups, immobilizing metal ions, and enabling ion exchange via biogenic carbonate formation processes. Finally, the developed BIBMFWCs could be used as a nature-based solution (NBS) material without in-situ pH control.

Co-adsorption mechanisms of As(V) and Cd(II) by three-dimensional flower-like Mg/Al/Fe-CLDH synthesized by "memory effect"

Due to the different physical and chemical properties such as surface charge and ion morphology between As(V) and Cd(II), it is challenging to remove As(V) and Cd(II), especially at low concentrations. This study constructed a novel three-dimension nanocomposite adsorbent Mg/Al/Fe-CLDH (CFMA) by "hydrothermal + calcination method". And different initial concentration ratios (Cd: As=1: 2, 1: 1, 2: 1) were used to investigate the removal performance of CFMA for Cd(II) and As(V). When the concentration ratio Cd: As=1: 2, the residual concentrations of As(V) and Cd(II) were 8.7 μg/L and 4.2 μg/L, respectively, which met the drinking water standard; In the co-adsorption system, As(V) and Cd(II) influence each other's adsorption behavior due to the anionic bridge and shielding effect of As(V) on Cd(II), As(V) gradually changed from monolayer adsorption to multi-layer adsorption dominant, while Cd(II) gradually changed from multi-layer adsorption to monolayer adsorption dominant. In this paper, the structure-activity relationship between material structure and synchronous removal of arsenic and cadmium was clarified, and the mechanism of synchronous removal was revealed, which provided technical guidance for synchronous removal of As(V) and Cd(II) from non-ferrous metal smelting wastewater.

The Thermophysical and Physicochemical Properties of the Aqueous Dispersion of Graphene Oxide Dual-Beam Thermal Lens Spectrometry

Modern heat-conducting materials require special attention to analyze their thermophysical properties. Compared to classical methods, thermal lens spectrometry (TLS) has advantages due to its high sensitivity to physical and chemical composition. To avoid a systematic error in the analysis of complex systems, it is necessary to realize the limits of the applicability of the method. This study considers the features of thermal-diffusivity measurements by TLS in the stationary state for dispersed systems with absorbances up to 0.05. The limits of applicability of the method in analyzing heterogeneous systems are shown, and a mathematical apparatus is proposed for indicating a systematic error in finding thermal diffusivity that does not exceed 1%. Graphene oxide (GO), which has attractive physicochemical properties, was used as the object of analysis. GO belongs to 2D objects, the study of which requires highly sensitive methods and special attention when discussing the results. The thermophysical properties of aqueous dispersions of graphene oxide in a wide range of concentrations (up to 2 g/L) and lateral sizes (up to 4 µm) were studied by TLS. It has been found that with increasing nanophase concentration, the thermal diffusivity of graphene oxide dispersions passes through a minimum, which can be used in solving thermal insulation problems. It has been established that prolonged laser irradiation of the dispersion leads to a change in thermal diffusivity, which indicates the photochemical reduction of graphene oxide.

Green preparation of graphene oxide nanosheets as adsorbent

As a basic building block of graphene-based materials, graphene oxide (GO) plays an important role in scientific research and industrial applications. At present, numerous methods have been employed to synthesize GO, there are still some issues that need to be solved, thus it is of importance to develop a green, safe and low-cost GO preparation method. Herein, a green, safe and fast method was designed to prepare GO, namely, graphite powder was firstly oxidized in a dilute sulfuric acid solution (H₂SO₄, 6 mol/L) with hydrogen peroxide (H₂O₂, 30 wt%) as oxidant, and then exfoliated to GO by ultrasonic treatment in water. In this process, H₂O₂ was the only oxidant, and no other oxidants were used, thus the explosive nature of GO preparation reaction in the conventional methods could be completely eliminated. This method has other advantages such as green, fast, low-cost and no Mn-based residues. The experimental results confirm that obtained GO with oxygen-containing groups has better adsorption property compared to the graphite powder. As adsorbent, GO can remove methylene blue (50 mg/L) and Cd²⁺ (56.2 mg/L) from water with removal capacity of 23.8 mg/g and 24.7 mg/g, respectively. It provides a green, fast and low-cost method to prepare GO for some applications such as adsorbent.

Emerging application of nanotechnology for mankind

Nanotechnology has proven to be the greatest multidisciplinary field in the current years with potential applications in agriculture, pollution remediation, environmental sustainability, as well as most recently in pharmaceutical industries. As a result of its physical, chemical, and biological productivity, resistance, and matricular organization at a larger scale, the potential of nanocomposites revealed different sorts of assembling structures via testing. Biosensors are known some specifically promising inventions whereas carbon nanotube, magnetic nanoparticles (NPs), quantum dots, and gold NPs showed capability to repair damaged cells, molecular docking, drug-delivery, and nano-remediation of toxic elements. PEGylated(Poly ethyl glycol amyl gated) redox-responsive nanoscale COFs drug delivery from AgNPs and AuNPs are known to be sun blockers in sunscreen lotions. The emerging trends and yet more to be discovered to bridge the gaps forming in the field of nanotechnology, especially insights into environmental concerns and health issues most importantly the food web which is connected with the well beings of mankind to perform its tasks giving necessary results. The current review detailed emerging role of nanomaterials in human life.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42247-023-00461-8.