Iron Nanoparticle-Incorporated Laser-Induced Graphene Filters for Environmental Remediation via an In Situ Electro-Fenton Process.

Laser-induced graphene (LIG) has garnered much attention due to its facile and chemically free fabrication technique. Metal nanoparticle incorporation into the LIG matrix can improve its electrical and catalytical properties for environmental application. Here, we demonstrate the fabrication of nanoscale zerovalent iron (nZVI) nanoparticle-incorporated LIG (Fe-LIG) and sulfidized-nanoscale zerovalent iron (S-nZVI) nanoparticle-incorporated LIG (SFe-LIG) surfaces. The sheets were first fabricated to investigate nanoparticle loading, successful incorporation in the LIG matrix, and electrochemical performance as electrodes. Fe-LIG and SFe-LIG sheets showed ∼3-3.5 times more charge density as compared with the control LIG sheet. The XPS and its deconvolution confirmed the presence of nZVI and S-nZVI in the Fe-LIG and SFe-LIG surfaces, which can generate in situ hydroxyl radical (•OH) via iron activation of electrogenerated hydrogen peroxide (H2O2) in short in situ electro-Fenton process. After confirmation of the successful incorporation of iron-based nanoparticles in the LIG matrix, filters were fabricated to demonstrate the application in the flow-through filtration. The Fe-LIG and SFe-LIG filters showed ∼10-30% enhanced methylene blue removal under the application of 2.5 V at ∼1000 LMH flux. The Fe-LIG and SFe-LIG filters also showed complete 6-log bacteria and virus removal at 2.5 and 5 V, respectively, while the LIG filters showed only ∼4-log removal. Such enhanced removal by the Fe-LIG and SFe-LIG filters as compared to LIG filters is attributed to the improved charge density, electrochemical activity, and in situ electro-Fenton process. The study shows the potential to develop catalytic LIG-based surfaces for various applications, including contaminant removal and microbial inactivation.

In-situ fabrication of titanium suboxide-laser induced graphene composites: Removal of organic pollutants and MS2 Bacteriophage.

Titanium suboxides (TSO) are identified as a series of compounds showing excellent electro- and photo-chemical properties. TSO composites with carbon-based materials such as graphene have further improved water splitting and pollutant removal performance. However, their expensive and multi-step synthesis limits their wide-scale use. Furthermore, recently discovered laser-induced graphene (LIG) is a single-step and low-cost fabrication of graphene-based composites. Moreover, LIG's highly electrically conductive surface aids in tremendous environmental applications, including bacterial inactivation, anti-biofouling, and pollutant sensing. Here, we demonstrate the single-step in-situ fabrication of TSO-LIG composite by directly scribing the TiO2 mixed poly(ether) sulfone sheets using a CO2 infrared laser. In contrast, earlier composites were derived from either commercial-grade TSO or synthesized TSO with graphene in multi step processes. The characteristic Ti3+ peaks in XPS confirmed the conversion of TiO2 into its sub-stoichiometric form, enhancing the electro-catalytical properties of the LIG-TiOx composite surface. Electrochemical characterization, including impedance spectroscopy, validated the surface's enhanced electrochemical activity and electrode stability. Furthermore, the LIG-TiOx composite surfaces were tested for anti-biofouling action and electrochemical application as electrodes and filters. The composite electrodes exhibit enhanced degradation performance for removing emerging pollutant antibiotics ciprofloxacin and methylene blue due to the in-situ hydroxyl radical generation. Additionally, the LIG-TiOx conductive filters showed the complete 6-log killing of mixed bacterial culture and MS2 phage virus in flow-through filtration mode at 2.5 V, which is ∼2.5-log more killing compared to non-composited LIG filers at 500 Lm-2h-1. Nevertheless, these cost-effective LIG-TiOx composites have excellent electrical properties and can be effectively utilized for energy and environmental applications.

Effect of Laser Parameters on Laser-Induced Graphene Filter Fabrication and Its Performance for Desalination and Water Purification.

Laser-induced graphene (LIG) is a low-cost, chemical-free single-step fabrication process and has shown its potential in water treatment, electronics, and sensing. LIG fabrication optimization is mostly explored for dense polyimide (PI) polymers. However, LIG-based filters and membranes for water treatment need to be porous, and additional steps are required to get porous surfaces from PI-based surfaces. Polyethersulfone (PES) porous membranes are cost-effective and are common in water purification as compared to PI; further, the optimization of LIG fabrication on PES-based porous membranes is not explored. So, this study demonstrated the fabrication, optimization, and characterization of LIG with different laser parameters such as power, speed, image density (ID), focusing, laser platforms, and membrane support layer effect on porous PES commercial (UP010) and lab-casted 15% PES (PES15) membranes. The performance of optimized LIG filters was tested for interfacial evaporation (IE)-based desalination in single and stacked layer configuration and water purification applications such as dye removal and disinfection. IE was done in Joule heating (JH) and solar heating (SH) modes, and the UP010-ID7 LIG filter showed the highest JH evaporation rates of ∼1.1, 1.8, and 2.82 kg m-2 h-1 in single, double, and triple stacked configurations, respectively. Using a JH IE setup, the best-performing UP010-ID7 LIG filters have also shown ∼100% removal of methylene blue dye from the contaminated water. Furthermore, all LIG filters showed a complete 6-log bacterial inhibition at the 5 V filtration experiments; at 2.5 V, the optimized LIG filters showed a higher removal than the non-optimized filters. Additionally, the LIGs obtained with the aluminum platform were the best quality. This work demonstrates that laser power, ID, platform, and membrane support are critical parameters for the best-performing PES-LIG filters, and they can be effectively utilized to fabricate PES-based LIG porous surfaces for various energy, environmental, and catalysis applications.

Magnéli-Phase Ti4O7-Doped Laser-Induced Graphene Surfaces and Filters for Pollutant Degradation and Microorganism Removal.

Laser-induced graphene (LIG) has recently become a point of attraction globally as an environmentally friendly method to fabricate graphene foam in a single step using a CO2 laser. The electrical properties of LIG are studied in different environmental applications, such as bacterial inactivation, antibiofouling, and pollutant sensing. Furthermore, metal or nonmetal doping of graphene enhances its catalytical performance in pollutant degradation and decontamination. Magnéli phase (TinO2n-1) is a substoichiometric titanium oxide known for its high electrocatalytic behavior and chemical inertness and is being explored as a membrane or electrode material for environmental decontamination. Here, we show the fabrication and characterization of LIG-Magnéli-phase (Ti4O7) titanium suboxide composites as electrodes and filters on poly(ether sulfone). Unlike undoped LIG electrodes, the doped Ti4O7-LIG electrodes exhibit enhanced electrochemical activity, as demonstrated in electrochemical characterization using cyclic voltammetry and electrochemical impedance spectroscopy. Due to the in situ generation of hydroxyl radicals on the surface, the doped electrodes exhibit increase in methylene blue degradation and microorganism removal. Effects of voltage and doping were examined, resulting in a clear trend of degradation and decontamination performance proportional to the doping concentration and applied voltage giving the best result at 2.5 V for 10% Ti4O7 doping. The LIG-Ti4O7 surfaces also showed biofilm inhibition against mixed bacterial culture. The flow-through filtration using a LIG-Ti4O7 conductive filter showed complete bacterial killing with 6 log removal in the permeate at 2.5 V, an enhancement of ∼2.5 log compared to undoped LIG filters at a flow rate of ∼500 L m-2 h-1. The facile fabrication of Ti4O7-doped LIG with enhanced electrochemical properties can be effectively used for energy and environmental applications.

Laser-Induced Graphene (LIG) as a Smart and Sustainable Material to Restrain Pandemics and Endemics: A Perspective.

A healthy environment is necessary for a human being to survive. The contagious COVID-19 virus has disastrously contaminated the environment, leading to direct or indirect transmission. Therefore, the environment demands adequate prevention and control strategies at the beginning of the viral spread. Laser-induced graphene (LIG) is a three-dimensional carbon-based nanomaterial fabricated in a single step on a wide variety of low-cost to high-quality carbonaceous materials without using any additional chemicals potentially used for antiviral, antibacterial, and sensing applications. LIG has extraordinary properties, including high surface area, electrical and thermal conductivity, environmental-friendliness, easy fabrication, and patterning, making it a sustainable material for controlling SARS-CoV-2 or similar pandemic transmission through different sources. LIG's antiviral, antibacterial, and antibiofouling properties were mainly due to the thermal and electrical properties and texture derived from nanofibers and micropores. This perspective will highlight the conducted research and the future possibilities on LIG for its antimicrobial, antiviral, antibiofouling, and sensing applications. It will also manifest the idea of incorporating this sustainable material into different technologies like air purifiers, antiviral surfaces, wearable sensors, water filters, sludge treatment, and biosensing. It will pave a roadmap to explore this single-step fabrication technique of graphene to deal with pandemics and endemics in the coming future.

Endocrinal Complications in Children and Adolescents with Thalassemia Major in Central India: An Observational Study.

OBJECTIVE: To determine the prevalence of short stature, delayed puberty, hypothyroidism, and diabetes mellitus in multiply transfused patients of beta thalassemia major and their correlation with serum ferritin. METHODS: A descriptive observational study was conducted in a tertiary care center in Indore, Madhya Pradesh from 2014 to 2016. All children with thalassemia major of the age group 8 to 18 y attending outpatient department or admitted in ward were included in the study. Detailed clinical history, demographic data, compliance to transfusion and chelation therapy, and growth parameters were recorded. Blood samples to look for endocrinopathies and serum ferritin were assessed. Tanner staging was done to assess for delayed puberty. RESULTS: Mean age of study participants (n = 50) was 15.98 ± 3.4 y. Short stature (n = 44; 88%), delayed puberty (n = 33; 71.7%), hypothyroidism (n = 6; 16%), and diabetes mellitus (n = 5; 10%) were the endocrinal abnormalities found. Mean serum ferritin level was 3122 ± 2117 ng/mL. Serum ferritin had significant positive correlation with serum TSH (thyroid stimulating hormone), fasting blood sugars, postprandial blood sugar, and delayed puberty. CONCLUSION: Evaluation of endocrinopatines must be carried out in thalassemia major patients regularly by pediatricians to detect and treat endocrinal complications. Importance of chelation therapy must be emphasized frequently to parents and patients.