Browsing by Author "Devendra Kumar Singh"

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A Facile and Simple Strategy for the Synthesis of Label Free Carbon Quantum Dots from the latex of Euphorbia milii and Its Peroxidase-Mimic Activity for the Naked Eye Detection of Glutathione in a Human Blood Serum
(American Chemical Society, 2019) Daraksha Bano; Vijay Kumar; Vikas Kumar Singh; Subhash Chandra; Devendra Kumar Singh; Pradeep Kumar Yadav; Mahe Talat; Syed Hadi Hasan
Herein a green synthetic route has been developed for the synthesis of water-soluble CQDs by facile single-step hydrothermal treatment of latexes of E. milii plant for the first time. This methodology is zero-cost; uses ultrapure water as a green solvent; does not use strong concentrated acid; and avoids the use of post surface passivating agents. The as-prepared CQDs exhibited excellent optical properties, including high QY up to 39.2%, resistance to high salt strength, and long time photostability. Furthermore, the as-prepared CQDs served as an intrinsic peroxidase-mimic activity to catalyze the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) associated with H 2 O 2 , which resulted into a blue-colored reaction with a characteristic absorbance peak at 652 nm. Afterward, the proposed TMB-based oxidation system act as a probe for the detection of GSH and offers the high selectivity relative to the different amino acids and various other interfering agents which can be easily seen with naked eye. The limit of detection (LOD) was found to be 5.3 nM in a linear range 0.02 to 0.1 μM of GSH concentration which showed to be superior under the optimal condition as compared with another probe. To demonstrate the practical feasibility for the GSH detection, the present system was successfully applied on human blood serums with good recovery. © 2018 American Chemical Society.
Effective removal of fluoride from water by coconut husk activated carbon in fixed bed column: Experimental and breakthrough curves analysis
(Elsevier B.V., 2018) Mahe Talat; Sweta Mohan; Viney Dixit; Devendra Kumar Singh; Syed Hadi Hasan; Onkar Nath Srivastava
The bio-waste coconut husk was converted into activated carbon through merely treating with KOH and thus obtained activated carbon was characterized by XRD, TGA, SEM and TEM analysis. The prepared activated carbon having very high surface area (1448 m2/g) was utilized as an adsorbent for the removal of fluoride (F-) from water. Fluoride adsorption experiments were performed on the laboratory-scale column at different bed height, flow rates, and F- concentrations to explore the potential of prepared adsorbent and it was found to be very efficient adsorbent as it showed high adsorption capacity 6.5 mg/g at pH 5, F- concentration 10 mg/L and adsorbent dose 1.4 g/L. Various breakthrough models i.e. Bed Depth Service Time (BDST), Thomas and Yoon–Nelson were applied on breakthrough data to analyze the breakthrough curves. The high R2 values obtained for the BDST model revealed its validity for this adsorption system. Breakthrough curves were successfully analyzed and described by both Thomas and Yoon–Nelson models. The exhausted adsorbent was efficiently regenerated with the 10% NaOH solution and regenerated adsorbent showed remarkable uptake capacity with a slight reduction in adsorption performance up to the 3 cycles. Life factor calculation indicated that adsorbent bed would have sufficient bed capacity up to 8.3 cycles to avoid breakthrough at time t = 0 and the bed would be completely exhausted after 9.0 cycles. © 2018
Introduction to Microplastics: Origin, Environmental Pathways, and Impacts on Ecosystems and Human Health
(Springer Science+Business Media, 2025) Vijay Kumar; Anupam Sunny; Khushaboo Verma; Ambneesh Mishra; Md Izhar Alam; Hira Lal Yadav; Javed Alam; Sweta Mohan; Devendra Kumar Singh
The plastics which were valued for their durability and versatility, have become ubiquitous in modern applications, from packaging to medicine. However, their non-biodegradable nature and poor waste management have led to severe environmental pollution, with over 430 million tons produced annually, which is projected to double by 2040. The improper disposal of such a huge plastic waste results in the release and accumulation of microplastics (MPs, < 5 mm) and nanoplastics (NPs, < 100 nm) in air, water, soil, and biota, which is being produced from both intentional production and degradation of larger plastics. These persistent MPs contaminate the various ecosystems, enter into the food chains through ingestion, inhalation, and dermal contact, and act as vectors for several toxic chemicals like heavy metals and polycyclic aromatic hydrocarbons, and increase their ecological and health impacts. In aquatic systems, MPs cause physical harm through ingestion and entanglement and reduces the growth and survival of organisms. In terrestrial environments, MPs disrupt soil structure, microbial activity, and nutrient cycling and impairs the health of plants. Human exposure to MPs is linked to respiratory, immune, and reproductive health issues, exacerbated by toxic additives like phthalates and flame retardants. The current chapter explores the sources, pathways, and impacts of MPs and NPs, emphasizing the urgent need for improved waste management, biodegradable alternatives, and global cooperation to mitigate plastic pollution and safeguard ecosystems and human health. © 2025 The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.
Photo-induced rapid biosynthesis of silver nanoparticle using aqueous extract of Xanthium strumarium and its antibacterial and antileishmanial activity
(Korean Society of Industrial Engineering Chemistry, 2016) Vijay Kumar; Ravi Kumar Gundampati; Devendra Kumar Singh; Medicherla V. Jagannadham; Shyam Sundar; Syed Hadi Hasan
The current work describes the biosynthesis of stable AgNPs using aqueous extract of Xanthium strumarium (AEX) which act as both reducing as well as a stabilizing agent. The biosynthesis was confirmed by UV-visible spectroscopy where the presence of SPR band at λmax 436 nm corresponded to the existence of AgNPs in reaction mixture. The optimum conditions for biosynthesis of AgNPs were 30 min of sunlight exposure time, 3.0% (v/v) of AEX inoculum dose and 3.5 mM AgNO3 concentration. The synthesized AgNPs was characterized by HRTEM, SAED, FESEM, EDX, XRD, AFM, and FTIR which showed potent antibacterial and antileishmanial activity. © 2016 The Korean Society of Industrial and Engineering Chemistry.
Synthesis of highly fluorescent nitrogen-rich carbon quantum dots and their application for the turn-off detection of cobalt (II)
(Elsevier B.V., 2019) Daraksha Bano; Vijay Kumar; Subhash Chandra; Vikas Kumar Singh; Sweta Mohan; Devendra Kumar Singh; Mahe Talat; Syed Hadi Hasan
In this study, we have reported easy and economical synthesis of highly fluorescent nitrogen-rich carbon quantum dots (N-CQDs). The as-prepared N-CQDs displayed strong blue color emission along with CIE co-ordinate index (0.15, 0.14). The N-CQDs possess comparatively high QY of 57% using quinine sulfate as a standard. Furthermore, the as-prepared N-CQDs defend against the high salt strength and longtime photostability over the six months of incubation. Apart from this, the as-prepared N-CQDs responded as a sensor for the ‘turn-off’ detection of Co2+ along with the detection limit of 0.12 μM over a linear range from 0.5 to 3 μM. The mechanistic study proved the detection of Co2+ was based on the IFE, static quenching, aggregation, and complex formation between the amino group of N-CQDs and Co2+. Moreover, the fluorescence of the quenched N-CQDs can reappear and get ‘turn-on’ by using GSH, AA, EDTA, and cyst; thus, the prepared N-CQDs could further execute as a probe for the Co2+ detection. Inspired by these outstanding properties, the as-prepared N-CQDs were also successfully employed for the practical application toward monitoring the trace level of Co2+ in a vitamin B-12 sample. © 2019 Elsevier B.V.