Adsorption and catalytic degradation of preservative parabens by graphene-family nanomaterials

Recent advancements on 2D nanomaterials as emerging paradigm for the adsorptive removal of microcontaminants

Water reservoirs are facing increasing prevalence of microcontaminants originating from agricultural runoff, industrial effluents, and domestic wastewater. The persistence of microcontaminants leads to disruptions in aquatic ecosystems and poses potential long-term health risks to humans, even at minimal concentrations. However, traditional wastewater treatment methods are inefficient to eliminate the microcontaminants because of their intricate chemical structures and low concentration. In this regard, nano-adsorption employing nanomaterials as adsorbents presents a viable alternative, offering enhanced efficiency and specificity towards the removal of microcontaminants. Amongst all, two-dimensional (2D) nanomaterials, including graphene oxide (GO), layered double hydroxides (LDHs), MXenes, and boron nitrides (BNs), exhibit distinctive characteristics such as a high surface area, remarkable chemical stability, and tendency of diverse surface functionalization, rendering them particularly effective in adsorbing pollutants from water. Therefore, the present review provides an exhaustive literature and comparative analysis of the aforementioned 2D nanomaterials-based adsorbents concerning their efficacy in adsorbing microcontaminants of pharmaceuticals and personal care products origin such as antibiotics, steroids, bisphenols, phthalates, parabens, and benzophenones. The different aspects of 2D adsorbents including adsorption capacity, mechanisms involved, kinetic and isotherm models followed for removal of a variety of microcontaminants have been congregated. Also, the information on recyclability, reusability, and stability of the adsorbents has been summarized to highlight their viability. Further, the limitations and future aspects related to the use of 2D nanomaterials-based adsorbents towards pollutant removal have been discussed. Overall, 2D nanomaterials holds great promise as efficient adsorbents for environmental remediation and can also be explored for industrial adsorption applications.

Review of the Integrated Approaches for Monitoring and Treating Parabens in Water Matrices

Due to their antibacterial and antifungal properties, parabens are commonly used as biocides and preservatives in food, cosmetics, and pharmaceuticals. Parabens have been reported to exist in various water matrices at low concentrations, which renders the need for sample preparation before their quantification using analytical techniques. Thus, sample preparation methods such as solid-phase extraction (SPE), rotating-disk sorptive extraction (RDSE), and vortex-assisted dispersive liquid-liquid extraction (VA-DLLE) that are commonly used for parabens extraction and preconcentration have been discussed. As a result of sample preparation methods, analytical techniques now detect parabens at trace levels ranging from µg/L to ng/L. These compounds have been detected in water, air, soil, and human tissues. While the full impact of parabens on human health and ecosystems is still being debated in the scientific community, it is widely recognized that parabens can act as endocrine disruptors. Furthermore, some studies have suggested that parabens may have carcinogenic effects. The presence of parabens in the environment is primarily due to wastewater discharges, which result in widespread contamination and their concentrations increased during the COVID-19 pandemic waves. Neglecting the presence of parabens in water exposes humans to these compounds through contaminated food and drinking water. Although there are reviews that focus on the occurrence, fate, and behavior of parabens in the environment, they frequently overlook critical aspects such as removal methods, policy development, and regulatory frameworks. Addressing this gap, the effective treatment of parabens in water relies on combined approaches that address both cost and operational challenges. Membrane filtration methods, such as nanofiltration (NF) and reverse osmosis (RO), demonstrate high efficacy but are hindered by maintenance and energy costs due to extensive fouling. Innovations in anti-fouling and energy efficiency, coupled with pre-treatment methods like adsorption, help mitigate these costs and enhance scalability. Furthermore, combining adsorption with advanced oxidation processes (AOPs) or biological treatments significantly improves economic and energy efficiency. Integrating systems like O₃/UV with activated carbon, along with byproduct recovery strategies, further advances circular economy goals by minimizing waste and resource use. This review provides a thorough overview of paraben monitoring in wastewater, current treatment techniques, and the regulatory policies that govern their presence. Furthermore, it provides perspectives that are critical for future scientific investigations and shaping policies aimed at mitigating the risks of parabens in drinking water.

Emerging Nanomaterials for Drinking Water Purification: A New Era of Water Treatment Technology

The applications of nanotechnology in the field of water treatment are rapidly expanding and have harvested significant attention from researchers, governments, and industries across the globe. This great interest stems from the numerous benefits, properties, and capabilities that nanotechnology offers in addressing the ever-growing challenges related to water quality, availability, and sustainability. This review paper extensively studies the applications of several nanomaterials including: graphene and its derivative-based adsorbents, CNTs, TiO2 NPs, ZnO NPs, Ag NPs, Fe NPs, and membrane-based nanomaterials in the purification of drinking water. This, it is hoped, will provide the water treatment sector with efficient materials that can be applied successfully in the water purification process to help in addressing the worldwide water scarcity issue.

Constructing N,S co-doped network biochar confined CoFe2O4 magnetic nanoparticles adsorbent: Insights into the synergistic and competitive adsorption of Pb2+ and ciprofloxacin

To solve the problem of biochar lack of adsorption sites for heavy metal ions and the difficulty of recycling, CoFe2O4 magnetic nanoparticles confined in nitrogen, sulfur co-doped 3D network biochar matrix (C-CoFe2O4/N,S-BC) was designed and fabricated successfully. The obtained C-CoFe2O4/N,S-BC displays remarkable adsorption performance for both Pb2+ and ciprofloxacin (CIP) removal at the single or binary system due to the role of N,S as metal ion anchoring compared to the N,S-free sample (CoFe2O4/BC). N,S co-doped BC not only participates in adsorption reaction but also effectively inhibites the agglomeration of CoFe2O4 nanoparticles and increases the active sites as a carrier at the same time. In the single system, CoFe2O4/N,S-BC demonstrates a fast adsorption rate (equilibrium time: 30 min) and high adsorption capacity (224.77 mg g-1 for Pb2+, 400.11 mg g-1 for CIP) towards Pb2+ and CIP. The adsorption process is befitted pseudo-second-order model, and the equilibrium data are in great pertinence with Langmuir model. In the binary system, the maximum adsorption capacity of CoFe2O4/N,S-BC for Pb2+ and CIP is 244.80 mg g-1 (CIP: 10.00 mg L-1) and 418.42 mg g-1 (Pb2+: 10.00 mg L-1), respectively. The adsorption mechanism is discussed based on the experimental results. Moreover, C-CoFe2O4/N,S-BC shows good practical water treatment capacity, anti-interference ability and stable reusability (the removal efficiency＞80% after eight cycles). The rapid, multifunctional, reusable, and easily separable adsorption properties make C-CoFe2O4/N,S-BC promising for efficient environmental remediation. This study also offers a viable method for the construction of adsorption material for complex wastewater treatment.

Biodegradation of Graphene Oxide by Insects (Tenebrio molitor Larvae): Role of the Gut Microbiome and Enzymes

Biodegradation of graphene materials is critical for understanding their environmental process and fate. Thus, biodegradation and mineralization of graphene oxide (GO) by an insect (yellow mealworms, Tenebrio molitor larvae) were investigated. Twenty mealworms could eat up a piece of GO film (1.5 × 1.5 cm) in 15 days. The ingested GO film underwent degradation, and the residual GO sheets were observed in the frass. Raman imaging confirmed that the residual GO (I_D/I_G, 1.16) was more defective than the pristine GO film (I_D/I_G, 0.95). ¹⁴C analysis showed that GO sheets were partially mineralized into CO₂ (0.26%) and assimilated into biomass compositions (e.g., lipid and protein) (0.36%). Gut microbes and extracellular enzymes in yellow mealworms played crucial roles in GO degradation, and the predominant gut microbes for GO biodegradation were identified as Enterobacteriaceae bacteria (e.g., Escherichia-Shigella sp.). Two biodegradation products belonging to hydroxylated or carboxylated aromatic compounds were formed with the assistance of electrons and hydroxyl radicals in mealworm guts. These findings are useful for better understanding the environmental and biological fate of graphene materials.