Pollutant Diesel Soot Derived Onion-like Nanocarbons for the Adsorption of Organic Dyes and Environmental Assessment of Treated Wastewater

Spectroscopic approach to optimize the biogenic silver nanoparticles for photocatalytic removal of ternary dye mixture and ecotoxicological impact of treated wastewater

The fabricating of extremely effective, economical, ecologically safe, and reusable nanoparticle (NP) catalysts for the removal of water pollution is urgently needed. This study, spectroscopically optimizes the process parameters for the biogenic synthesis of AgNP catalysts using Cledrdendrum infortunatum leaf extract. The optimization of several synthesis parameters was systematically studied using UV-Vis spectroscopy to identify the ideal conditions for AgNPs formation. The AgNPs are spherical with a size of ~ 20 nm, pure and stable. Mechanistic insights into the biogenic synthesis process were explored. The photocatalytic performance of biogenic AgNPs was evaluated for the degradation of three common (crystal violet, thioflavin T, and methylene blue) dyes as models in ternary mixtures under the influence of sunlight. AgNPs show excellent photocatalytic efficiency in terms of degradation percentage (82.89-96.96% within 110 min), kinetics (0.0247-0.0331 min-1), half-life (20.96-28.11 min), and T80 (48.67-65.28 min) and also easily recovered and reused. Ecological safety assessment of the treated wastewater was assessed on the growths of rice, mustard, and lentil plants, and preliminary findings demonstrated that seedling growths for treated wastewater were nearly similar to the control sample but retarded in dye-contaminated wastewater suggesting potential use of treated wastewater for sustainable agriculture without compromising ecological balance. So, this study explores biogenic AgNPs as cost-effective, safe, and sustainable photocatalytic agents for the remediation of hazardous mix dyes and real-life applications of treated water for agricultural purposes.

Biomass-derived multiatom-doped carbon dots for water sensing based on excited state intraparticle proton transfer in organic solvents

The presence of trace water impurities in organic solvents can significantly influence chemical reactions and product quality; thus, the accurate detection of water content in these solvents is a critical requirement for industrial applications. Accordingly, an eco-friendly, effective, and economical sensor for detecting trace quantities of miscible water in organic solvents is required for industrial applications. In this study, we synthesized biomass-derived multi-atom-doped carbon dots (MACDs) as fluorescent probes and employed them for the detection of trace amounts of water impurities in several water-miscible organic solvents. The MACDs exhibited stable dual-color fluorescence emission under ultraviolet light irradiation and red and blue emissions in organic solvents and water. The fluorescence quantum yield was approximately 11 %, which indicates an excited intraparticle proton transfer response due to an increase in the water content within a wide response range from 0 % to 100 % (v/v) in organic solvents. The intensity of the red emission signal at 670 nm gradually decreased with an increase in the water content in the organic solvent. The MACDs could detect water with an instant response time of 55 s, a high sensitivity, and low limits of detection of 0.08 %, 1.36 %, 0.03 %, 0.04 %, 0.12 %, and 0.05 % (v/v) in ethanol, acetonitrile, dimethylformamide, methanol, isopropanol, and tetrahydrofuran, respectively. Hence, biomass-derived MACDs can serve as efficient and eco-friendly water sensors in organic solvents.

Waste-Derived Carbon Nano-Onions for the Removal of Organic Dye from Wastewater and Phytotoxicity Studies

Dyes are extensively employed in industries, namely, textiles, cosmetics, paper, pharmaceuticals, tanning, etc. The effluent released from these industries contains various kinds of harmful dyes that adversely impact living beings and the environment due to their recalcitrant and toxic nature. In this study, an effort has been made to eliminate the methylene blue (MB) from wastewater using carbon nano-onions (CNOs) produced from waste frying oil (WFO) using an economical and eco-friendly wick pyrolysis method. The impact of process variables, namely, pH, temperature, process time, MB dye concentration, and adsorbent, was examined for optimum dye removal. The dye removal efficiency (RE) of 99.78% was obtained in 20 min under optimum conditions. The pseudo-second-order model demonstrated a better kinetic fitting with the experimental data. The Langmuir model represented the maximum adsorption capacity (q max) of 43.11 ± 2.56 mg g-1. The regeneration studies demonstrated that the CNOs achieved ∼99.6% MB dye removal over three cycles. Brassica nigra seeds irrigated in treated wastewater showed better growth (3.29 cm) than untreated dye wastewater, which confirms the environmental sustainability of the overall process.

Heteroatom Doping in Pollutant Diesel Soot-Derived Nanocarbon for Enhanced Zn-Ion Storage Performance

Herein, we have isolated onion-like nanocarbon (ONC) from the exhaust soot of diesel engines and further doped it with nitrogen (N) and sulfur (S) to fabricate N,S-co-doped ONC (N-S-ONC). To explore its application feasibility, we have assembled an aqueous Zn-ion hybrid supercapacitor (ZIHSC) with a N-S-ONC cathode, which attains high specific capacitance with good rate capability. In-depth analyses suggest that the mechanism of charge storage in the ONC is governed by both capacitive-controlled and diffusion-controlled processes, with the capacitive processes leading at all sweep rates. The ZIHSC demonstrated a good energy density of 50 Wh/kg, a maximum power density of 3.6 kW/kg, and an impressive cycle life with 73% capacitance retention after 50,000 charge-discharge cycles. The study suggests the potential possibly for the long-term application of BC derived nanocarbon in electrochemical energy storage systems (EESSs).

The efficiency of bio-char as bitumen modifier

Improving the mechanical properties of bitumen is an important goal for road pavements design. For this reason, new compounds are now being sought for testing as bitumen modifiers. In this work, the authors studied the effect that two different chars have on two 50/70 bitumens with different chemical and physical characteristics. A complete morphological, surface and bulk characterization of the two additives was carried out. In addition, rheology, Nuclear Magnetic Resonance (NMR) relaxometry and atomic force microscopy were used to analyze the effect that the two additives exert on the properties of the bitumens. According to the results, the char sample with high porosity could be used as a modifier of mechanical properties, while no rejuvenation effects were observed for either of the two additives tested. In addition, the two additives do not give rise to segregation phenomena.

Biomass-derived carbon nano-onions for the effective elimination of organic pollutants and oils from water

Oil spillage and leakage of organic solvents have caused severe environmental and ecological damages. It is of great significance to develop a cost-efficient and green adsorbent material with high uptake efficiency to separate the oil-water mixture. In this work, biomass-derived CNOs were first time explored in the adsorption of organic pollutants and oils from water. Carbon nano-onions (CNOs) with hydrophobicity and oleophilicity were cost-effectively synthesized in an energy efficient flame pyrolysis process using flaxseed oil as a carbon source. The as-synthesized CNOs without any further surface modification have shown high adsorption efficiency in removing organic solvents and oils from the oil-water mixture. The CNOs could adsorb diverse organic solvents such as pyridine (36.81 mg g^-1), dichloromethane (90.95 mg mg^-1), aniline (76 mg mg^-1), toluene (64 mg mg^-1), chloroform (36.25 mg mg^-1), methanol (49.25 mg mg^-1), and ethanol (42.25 mg mg^-1). The uptake capacity for petrol and diesel over CNOs was observed at 36.68 mg mg^-1 and 58.1 mg mg^-1, respectively. The adsorption of pyridine followed pseudo-second-order kinetics and Langmuir's isotherm model. Moreover, the adsorption efficiency of CNOs towards the remediation of pyridine was almost similar in real-water samples when tested in tap water, dam water, groundwater, and lake water. Similarly, the practical applicability for the separation of petrol and diesel was also verified in the real sample (sea water) and has been proven to be excellent. By simple evaporation, the recovered CNOs can be reused for more than 5 cycles. CNOs exhibit the promising potential to be used in practical applications for oil-polluted water treatment.

Multifunctional carbon dots for glutathione detection and Golgi imaging

Glutathione (GSH) is present in almost every cell in the body and plays various integral roles in many biological processes. The Golgi apparatus is a eukaryotic organelle for the biosynthesis, intracellular distribution, and secretion of various macromolecules; however, the mechanism of GSH in the Golgi apparatus has not been fully elucidated. Here, specific and sensitive sulfur-nitrogen co-doped carbon dots (SNCDs) with orange-red fluorescence was synthesized for the detection of GSH in the Golgi apparatus. The SNCDs have a Stokes shift of 147 nm and excellent fluorescence stability, and they exhibited excellent selectivity and high sensitivity to GSH. The linear response of the SNCDs to GSH was in the range of 10-460 μM (LOD = 0.25 μΜ). More importantly, we used SNCDs with excellent optical properties and low cytotoxicity as probes, and successfully realized golgi imaging in HeLa cells and GSH detection at the same time.

Sustainable carbon nano-onions as an adsorbent for the efficient removal of oxo-anions

The increasing threats of oxo-anions in drinking water have posed a serious threat to human health, aquatic environment, ecology, and sustainability. Accordingly, developments of cost-effective and sustainable nanomaterials for water remediation are on top priority and highly sought in global research community. Carbon nano-onions (CNOs) are one of the emerging nanomaterials for water purification because of its unique morphology, surface reactivity, high density of surface-active sites, and microporous structure. Herein, flaxseed oil-derived CNOs are utilized as efficient adsorbent for the removal of toxic oxo-anions. Aside from the green and economic nature, CNOs provide high adsorption efficiency ~ 806.45 mg g^-1 for the removal of [Formula: see text] (99.9%) from aqueous system at ambient temperature, neutral pH in 70 min. The adsorption of [Formula: see text] onto CNOs was well fitted in pseudo-second order kinetics and followed the Langmuir adsorption isotherm model. The adsorption process was determined to be exothermic and spontaneous from the resulting thermodynamic characteristics. Furthermore, the high hydrophobic nature of CNOs make it recycling simpler. The real-life applicability of CNOs towards [Formula: see text] removal was tested in tap water, river water, and dam water. With all these observed results, CNOs show promise for practical water remediation applications.

Non-aqueous onion like nano-carbons from waste diesel-soot used as FRET-based sensor for sensing of nitro-phenols

Herein, a simple-functionalization method is described to prepare the oleylamine functionalized non-aqueous version of onion-like nanocarbons (ONC-OA), where ONC was isolated from the waste pollutant soot exhausted from the diesel engine. The surface group analysis of ONC-OA has been investigated via Nuclear Magnetic Resonance and X-ray Photoelectron Spectroscopy. ONC-OA shows blue fluorescence with a quantum yield of ∼6% in tetrahydrofuran (THF). The fluorescence-based sensing applications of ONC-OA has been investigated for selective sensing of toxic aromatic nitro-phenols compounds (para-nitro, dinitro, and trinitro phenols) from the tested many nitro organic compounds. Based on the limit of detection values, ONC-OA shows much better results for tri-nitro phenol compared to di and mono nitrophenol. To understand the quenching mechanism, a time-resolved photoluminescence analysis of the sensor with and without the addition of quenchers is performed. The effective lowering in fluorescence lifetime of the sensor after the addition of quenchers concludes that the quenching observed is majorly due to the Förster Resonance Energy Transfer (FRET) mechanism. The real-life application of ONC-OA was analyzed by external spiking of N-PhOHs in soil samples.

An overview on atmospheric carbonaceous particulate matter into carbon nanomaterials: A new approach for air pollution mitigation

Air pollutants consisting of atmospheric particulate matter (PM) poses a major threat to the environment and human health. However, due to their carbonaceous nature, these atmospheric PM can also be used as a precursor for fabrication of high-valued carbon nanomaterials (CNMs) leading to waste to wealth as well as mitigation of air pollution. Over the few years, various results have been reported on different types of physical and chemical methods for the synthesis of CNMs from atmospheric particulate matter with the help of top down and bottom up methods; however, there is a lack of review on these innovative processes and outcome in order to assess their feasibility and suitability for further investigation. This review critically assesses the synthesis, identification, and characterization of different types of CNMs derived from the atmospheric PM. The fascinating fluorescence properties along with the novel multifarious applications of such PM-derived CNMs are also extensively discussed in this review work. This unique review will certainly help to make a new avenue for air pollution mitigation through conversion of PMs in to value added nanomaterials (VNMs) and will boost the research activity in the field of environmental nanotechnology for a cleaner environment.

Carbon Graphitization: Towards Greener Alternatives to Develop Nanomaterials for Targeted Drug Delivery

Carbon nanomaterials have attracted great interest for their unique physico-chemical properties for various applications, including medicine and, in particular, drug delivery, to solve the most challenging unmet clinical needs. Graphitization is a process that has become very popular for their production or modification. However, traditional conditions are energy-demanding; thus, recent efforts have been devoted to the development of greener routes that require lower temperatures or that use waste or byproducts as a carbon source in order to be more sustainable. In this concise review, we analyze the progress made in the last five years in this area, as well as in their development as drug delivery agents, focusing on active targeting, and conclude with a perspective on the future of the field.

Preparation of a hybrids APT@MIL by one-step solvent-thermal method for effectively degrading organics

The attapulgite (APT), a typical nano-rod structured clay was introduced to MIL-101(Fe), a typical eco-friendly iron-based Metal-Organic Framework material (MOF), during the preparation by a one-step solvothermal method, which afforded a novel APT and MOF hybrid (APT@MIL). Based on the characterization of SEM, FT-IR and XRD, it was found that the rod-like crystals of APT determined the size of MIL-101(Fe) while maintaining its regular octahedral crystal form, and the crystal size of MIL-101(Fe) in APT@MIL enlarged 4 times. It was also discovered that the rod-like APT were evenly distributed in MIL-101(Fe) crystals. Using APT@MIL as the photocatalyst, some organic dyes were photodegraded in simulated sunlight. The analysis indicated that APT@MIL has high adsorption and photodegradation activity, the removal rate of methylene blue was up to 99.5%. Finally, the photocatalytic activity of APT@MIL was verified by UV-Vis DRS, photoluminescence spectra. The thermodynamic adsorption, kinetic characteristics adsorption, and removal mechanism of APT@MIL are also discussed. In summary, a novel hybrid material APT@MIL was successfully prepared with good adsorption and photocatalytic performance. It is expected to be used in photocatalytic degradation of dye wastewater.

Recent Advances in Methods for the Recovery of Carbon Nanominerals and Polyaromatic Hydrocarbons from Coal Fly Ash and Their Emerging Applications

Coal fly ash is found to be one of the key pollutants worldwide due to its toxic heavy metal content. However, due to advancements in technology, coal fly ash has gained importance in various emerging fields. They are rich sources of carbonaceous particles which remain unburnt during burning of various coals in thermal power plants (TPPs). Various carbonaceous nanoparticles in the form of fullerenes, soot, and carbon nanotubes could be recovered from coal fly ash by applying trending techniques. Moreover, coal fly ash is comprised of rich sources of organic carbons such as polycyclic and polyaromatic hydrocarbons that are used in various industries for the development of carbon-derived value-added materials and nanocomposites. Here, we focus on all the types of carbon nanominerals from coal fly ash with the latest techniques applied. Moreover, we also emphasize the recovery of organic carbons in polyaromatic (PAHs) and polycyclic hydrocarbons (PCHs) from coal fly ash (CFA). Finally, we try to elucidate the latest applications of such carbon particle in the industry.

Upgrading of diesel engine exhaust waste into onion-like carbon nanoparticles for integrated degradation sensing in nano-biocomposites

Onion-like carbon nano particles are separated from diesel engine exhaust “pollutant soot” and used in the structural health monitoring of a biocomposite.

Surface adhered fluorescent carbon dots extracted from the harmful diesel soot for sensing Fe(iii) and Hg(ii) ions

A simple cost effective isolation method has been described for the extraction of surface-adhered blue–green fluorescent carbon material from the diesel soot and used them for the selective sensing of Fe(iii) and toxic Hg(ii) metal ions in aqueous medium.

Bio-mass derived functionalized graphene aerogel: a sustainable approach for the removal of multiple organic dyes and their mixtures

Herein, fabrication of a functionalized graphene aerogel (f-GA) from a biomass (pear fruit)-derived graphene aerogel (GA) is described. f-GA is showing better adsorption capacity towards CV, MB and RhB dyes than GA and activated charcoal.