Green Chemistry Route Research Articles

Green Synthesis of Engineered CdS Nanoparticles with Reduced Cytotoxicity for Enhanced Bioimaging Application.

The modern epoch of semiconductor nanotechnology focuses on its application in biology, especially in medical sciences, to fetch direct benefits to human life. Fabrication of devices for biosensing and bioimaging is a vibrant research topic nowadays. Luminescent quantum dots are the best option to move with, but most of them are toxic to living organisms and hence cannot be utilized for biological applications. Recent publications demonstrate that surface treatment on the nanoparticles leads to enhanced luminescence properties with a drastic reduction in toxicity. The current work introduces surface-modified CdS, prepared via a simple green chemical route with different medicinal leaf extracts as the reaction media. Lower toxicity and multiple emissions in the visible region, observed for the CdS-O.tenuiflorum hybrid structures, make them a better option for future biological applications. Furthermore, the hybrid structure showed enhanced electrical properties, which promises its use in modifying the current optoelectronic devices.

Magnetic cobalt oxide nanosheets: green synthesis and in vitro cytotoxicity.

Cobalt oxide nanoparticles were prepared via green chemistry route and fully characterized by Field Emission Scanning Electron Microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM) and Transmission electron microscopy (TEM) analyses; the CoO and Co3O4 nanoparticles, in sheet-shaped cobalt oxide form, ensued simultaneously in one step. The varying concentrations of NPs were analyzed via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test on the cancer cell line (U87) which revealed that with increasing concentration of cobalt oxide nanoparticles, the survival rate of U87 tumor cells decreases; IC50 of nanoparticles being ~ 55µg/ml-1.

Watermelon Peel‐Derived Heteroatom‐Doped Hierarchical Porous Carbon as a High‐Performance Electrode Material for Supercapacitors

AbstractThis work presents for the first time the systematic characterization and excellent supercapacitor performance of heteroatom‐doped porous carbon materials (HPC) synthesized by direct pyrolysis of watermelon peel and urea via molten salt template route in air with non‐toxic activating agent. The molten salt not only protects the derived carbon from burning during high‐temperature pyrolysis, but can also be etched to generate abundant hierarchical pores in the final products. The obtained HPC exhibits a high specific surface area of 1660 m2 g−1 and shows high specific capacitances of up to 278 F g−1 in 1 M H2SO4 electrolyte. The symmetrical device also demonstrates a remarkable specific capacitance of up to 226 F g−1 and ultrahigh initial capacitance retention of 98 % after 10,000 cycles of charge/discharge at the current density of 10 A g−1. The porous carbon produced via this green chemical activation route demonstrates great potential as electrode materials in supercapacitor.

Epitaxial deposition of LaF3 thin films on Si using deep eutectic solvent based facile and green chemical route

Epitaxial lanthanum fluoride (LaF3) is considered an important and outstanding material for the fabrication of Metal–Insulator–Semiconductor (MIS) capacitive devices. In the quest of finding a green and low-cost scalable technique for the epitaxial deposition of LaF3 thin-film, this article presents an investigation on a home-made deep eutectic solvent (DES)-based chemical route for LaF3 thin film deposition on p-type silicon (p-Si) using the spin coating technique. The x-ray diffraction study confirmed the epitaxial deposition of LaF3 film on the p-Si substrate. An almost pinhole-free homogeneous surface and nearly stoichiometric epitaxial LaF3 were observed on the Si substrate through scanning electron microscopy and energy dispersive x-ray spectroscopy, respectively. From the capacitance–voltage (C–V) characteristics, the capacitance of the Ag/LaF3/p-Si/Ag device with four-layer LaF3 was maximum among the Ag/LaF3/p-Si/Ag devices with two-layer, four-layer, and six-layer LaF3. The flat band potential of the Ag/LaF3/p-Si/Ag structure was determined from the Mott–Schottky plot. The experimental results indicate that the DES-based epitaxial deposition of LaF3 film on the p-Si substrate could be a highly promising technique for the fabrication of LaF3-based MIS capacitive devices.

Green Chemistry Synthesis of Nano-Hydroxyapatite using Natural Stabilisers

Present work describes the synthesis and characterization of Nano- Hydroxyapatite (nano-HAP) powders through green chemistry route, using Natural Stabilizers (NS) as precursors. The synthesized powders possess crystallite and particles of sizes in nano range. The nature of the powder is poly dispersive. The morphology of synthesized powders is near spherical and the pH value is greater than the ten. The powder possesses similar dielectric constant value of 100 Hz at room temperature, as reported in literature. The corresponding wave numbers of the nano-HAP powder match with the reported functional groups.

Selective electrochemical determination of paracetamol using hematite/graphene nanocomposite modified electrode prepared in a green chemical route

An eco-friendly procedure for the preparation of high-quality graphene incorporated iron oxide nanocomposite is reported, which is effectively used for the electrochemical determination of acetaminophen drug. The graphene dispersion is prepared by the exfoliation of graphite in a green solvent (water/ethanol 90:10 vol%/vol%) in the presence of a non-ionic surfactant for better yields. Material characterization studies reveal the lower deficiency nature of graphene sheets as well as the exclusive formation of the hematite phase of iron(III) oxide in the nanocomposite. Electrocatalytic sensing of paracetamol is carried out using cyclic voltammetric and differential pulse voltammetric measurements. A high linear concentration range of 0.3 μM–1800 μM paracetamol is observed over the hematite/graphene nanocomposite modified glassy carbon electrode. The nanocomposite is found to be highly selective in the detection of paracetamol with the presence of dopamine and other common contaminants interfered in human sample analysis. The analytical utility of the hematite/graphene-modified electrode in the estimation of the real tablet sample is also investigated.

Green chemistry route of biosynthesized copper oxide nanoparticles using Psidium guajava leaf extract and their antibacterial activity and effective removal of industrial dyes

In current scenario, the eco-friendly and non-toxically biosynthesis of cupric oxide is also known as copper oxide nanoparticles (CuO NPs) by using Psidium guajava (P. guajava) leaf extract to potential valuable in the wastewater treatment as well as biomedical application. To this unique technology for biosynthesis of CuO NPs was utilizing phytocompounds from aqueous plant extract during the reaction mixture, which possessed natural bio-compounds to act as stabilizing, capping and reducing agent of CuO NPs. In the present investigation, biosynthesized CuO NPs and their physicochemical properties were analyzed by using ultraviolet–visible spectroscopy (UV) was initially to be identified formation of CuO NPs the characteristic peak at 265 nm. Furthermore, Fourier-transform infrared spectroscopy (FTIR) analysis to be confirmed functional groups of biosynthesized CuO NPs the absorption range of 624–870 cm‐1 and the X-ray diffraction (XRD) study was performed to determine the monoclinic crystalline structure of the CuO NPs. Field emission scanning electron microscopy (FE-SEM) and High-resolution transmission electron microscopy (HR-TEM) with Selected area electron diffraction (SAED) pattern to analyzed for the identification of particles surface morphology showed oval and platelets and sizes range from 40 to 150 nm. Energy-dispersive X-ray spectroscopy (EDS) spectrum to confirmed quantitative evaluation of Cu and O elements in the prepared samples. Dynamic light scattering (DLS) to determined average particles size of CuO NPs 153 nm. The prepared CuO NPs was observed highest anti-bactericidal activity against Gram negative (G−) bacteria of Escherichia coli, Pseudomonas aeruginosa and then compared to Gram positive (G+) bacteria of Streptococcus pneumoniae, Staphylococcus epidermidis to be confirmed using agar well diffusion, and their NPs interaction on the bacterial membrane to be confirmed by confocal laser scanning microscopic (CLSM) to visualized live/dead bacterial cells. In addition to be performed the biosynthesized CuO NPs has potential industrial dye removal of congo red (CR) and methylene blue (MB) under the sunlight irradiation.

Synthesis of KAlSiO4 by Hydrothermal Processing on Biotite Syenite and Dissolution Reaction Kinetics

To make potassium from K-bearing rocks accessible to agriculture, processing on biotite syenite powder under mild alkaline hydrothermal conditions was carried out, in which two types of KAlSiO4 were obtained successfully. The dissolution-precipitation process of silicate rocks is a significant process in lithospheric evolution. Its effective utilization will be of importance for realizing the comprehensiveness of aluminosilicate minerals in nature. Two kinds of KAlSiO4 were precipitated in sequence during the dissolution process of biotite syenite. The crystal structures of two kinds of KAlSiO4 were compared by Rietveld structure refinements. The kinetics model derived from geochemical research was adopted to describe the dissolution behavior. The reaction order and apparent activation energy at the temperature range of 240–300 °C were 2.992 and 97.41 kJ/mol, respectively. The higher dissolution reaction rate of K-feldspar mainly relies on the alkaline solution, which gives rise to higher reaction order. During the dissolution-precipitation process of K-feldspar, two types of KAlSiO4 with different crystal structure were precipitated. This study provides novel green chemical routes for the comprehensive utilization of potassium-rich silicates.

Enhanced Removal of Crystal Violet Dye and Anti-Biofilm Activity of Ti Doped CeO2 Nanoparticles Synthesized by Phoenix Dactylifera Mediated Green Method

Currently eco-friendly green method is used for the synthesis of biocompatible pure and Ti doped cerium oxide nanoparticles. Various chemical methods have been reported for the synthesis of nanomaterials. In the present work, the green chemistry route was employed for the synthesis of Ti doped CeO2 nanoparticles (nanoceria) by Phoenix Dactylifera fruit extract. Their structural, morphological and optical properties were investigated by XRD, XPS, UV-DRS, GC–MS, FTIR and TEM. Structural analysis confirms the formation of Ti doped CeO2 nanoparticles with particle size ranging from 7 to 9 nm and XPS analysis confirms the presence of Ti+4 ions in CeO2 nanoparticles. It was observed that Ti doped CeO2 nanoparticles (NPs) exhibited the enhanced removal of crystal violet dye and maximum degradation was obtained by 15% Ti doped nanoceria. Antibiofilm activity of Ti doped CeO2 nanoparticles were also investigated against P. aeruginosa PAO1, which shows maximum antibiofilm activity for 20% Ti doped CeO2 nanoparticles.

Solution processed copper zinc tin sulfide thin films for thermoelectric device applications

In this work, Cu2ZnSnS4 (CZTS) thin film has been fabricated on a soda-lime glass substrate through an economical green chemical route employing nebulizer assisted spray pyrolysis technique. The deposition is carried out under ambient atmospheric pressure without annealing and sulphurization. An investigation was done to reveal the temperature dependence of various characteristics especially the thermoelectric property of this Earth-abundant, nontoxic CZTS films in the range of 300 °C–375 °C. This study reveals the thermoelectric conversion capability of the material in addition to its photovoltaic conversion application. XRD spectra revealed the formation of tetragonal structured kesterite CZTS peaks preferentially oriented along [112] direction. The film thickness and size of the crystallites is found to increase with temperature up to 350 °C while the dislocation density and microstrain decreased. Raman spectra exhibit a phase pure CZTS layer free from secondary and tertiary phases at a substrate temperature of 300 °C whose composition seems to be off stoichiometric with a Cu/(Zn + Sn) ratio of 0.78. The surface morphological analysis shows a dense, smooth and compact surface for the 350 °C sample. The bandgap was found to vary in the range of 1.52–1.74 eV. Refractive index, extinction coefficient and electrical characteristics of the prepared films endorse its usage as an absorber material for thin-film photovoltaic energy conversion. The Seebeck coefficient of 350 °C grown film is found to be 153 μV/K and the corresponding power factor increases to 5.76 × 10−3 W/mK−2 which recommends its utility in the thermoelectric devices.

Comparing sustainable methods for synthesis of natural benzaldehyde from trans‐cinnamaldehyde: Experimental analysis

AbstractNatural benzaldehyde is an aromatic flavor compound. Compared to the chemical synthesis route, the natural benzaldehyde that is produced from natural source such as cassia oil is very expensive. To overcome the problem, many researchers have reported and proposed different processes such as ozonization process, near‐critical water hydrolysis process, toxic phase transfer, or surfactants catalytic process. This paper presents a comparison of three green chemical routes using aqueous systems: (H2O/OH‐), (H2O/OH‐/H2O2), (H2O, cellulose‐based heterogeneous catalyst/OH‐), applied to this transformation. First experimental results show remarkable conversion for the first and third systems. Best yields are obtained using the first simple route with, for example, a nearly 80 % conversion together with a 43 % selectivity.

Recent advances in the synthetic chemistry of 1,5‐benzothiazepines: A minireview

AbstractBenzothiazepine, a prominent “drug prejudice core”, is a heterocyclic moiety of immense importance due to its presence in a wide range of bioactive compounds. They act as a primary “biolinker” in diverse synthetic routes to obtain bioactive molecules and serve as important templates in synthetic and medicinal chemistry. They are known to possess a plethora of pharmacological activities, which include Ca2+ channel blockers, CNS acting agents, anti‐HIV, ACE inhibitors, antimicrobial, antifungal, anticancer. Their promising behaviour as drug molecules led the scientific community to develop novel, mild, green, and highly efficient synthetic routes for their synthesis. The conventional synthesis generally involved the condensation of chalcones with 2‐aminothiophenol in the presence of acid/base with high‐temperature heating, mostly resulting in poor yields or mixtures. However, recent trends are replacing these conditions with mild and green conditions through organocatalysis or other methodologies. In this review, an attempt has been made by authors to summarize (a) Recent developments in the synthetic strategies of 1,5‐benzoathiazepines and its derivatives (b) Conventional methods for the synthesis of 1,5‐benzothiazepines including progress in the green chemistry routes (c) Applications of various metals and organocatalysts to achieve the enantioselective synthesis of title compounds.

Effect of Process Parameters on the Microstructural Properties of Silica Extracted from Agro-Waste

This research paper investigates the influence of process parameters during the synthesis process of silica on its micro-structural properties such as size, crystalline or amorphous behavior, surface morphology, purity, functional groups attached etc. In this work, silica and nano silica are extracted from Rice Husk Ash (RHA) which is an agro waste by green chemistry route. The extracted silica is of very high purity and non-toxic which can be used for health care applications. Alkali Extraction and Reflux methods are used to extract silica and nano silica from RHA. The process parameters taken into consideration while obtaining silica were incineration temperature, duration of heating and method used for cooling the rice husk samples heated in muffle furnace. The base material rice husk was heated at different temperatures in the muffle furnace for different durations. The converted rice husk ash was cooled by two different methods. The effect of process parameters on microstructures and compositional features of silica and nanosilica was studied using advanced characterization techniques XRD, SEM, TEM, EDS, Raman Spectroscopy and UV/Visible spectroscopy. The study shows that the process parameters affect the microstructural properties and morphology of silica significantly, which is a very interesting finding. It will help to synthesize silica with different lattice structures for different applications via green route. Silica is a chemical which is in high commercial demand for various industrial applications. This is an economic, environment friendly and simple method to extract non-toxic silica which can be used for biomedical and health care applications as well.

Novel betaine-amino acid based natural deep eutectic solvents for enhancing the enzymatic hydrolysis of corncob

A novel natural deep eutectic solvent (NDES) with water content ranging from 65 to 93 wt%, in which betaine (Bet) acts as the cation and amino acids (AAs) as the anions, was prepared by a simple and green chemical route. [Bet][AA] NDES showed excellent xylan and lignin solubility, however, scare cellulose solubility. A mild and facile pretreatment process with [Bet][AA] NDES was carried out at 60 °C for 5 h. The enzymatic hydrolysis efficiency of cellulose and corncob was significantly improved. Detailed characterization showed that the enhancement of cellulose digestibility derived mainly from xylan and lignin removal. Xylan and lignin removal for [Bet][Lys]-W87 was 47.68 and 49.06%, while it was 42.20% and 57.01% for [Bet][Arg]-W82, respectively. FT-IR, SEM, XRD, and HSQC NMR studies confirmed the effectiveness and mechanism of [Bet][Lys]-W87 and [Bet][Arg]-W82 on biomass pretreatment.

Structurally improved reduced graphene oxide nanocluster structured assembly with Naringin for the effective photothermal therapy of colon tumour patients and nursing care management

Functionalization of naringin (Nar) on a nanomaterials surface will decrease their detrimental side effects and escape them from immunological rejection. In this study, we developed a sustainable green chemistry route to fabricate naringin-reduced graphene oxide nanosheets (rGO@Nar) through the easy method. The hydroxyl group of Naringin reduces and generates the functionalization of rGO@Nar, and it was confirmed through various spectroscopic method (FT-IR and Raman) and electroscopic methods (FE-SEM and HR-TEM). After careful evaluation of the nanocomposion, we performed cancer cell growth inhibition properties of the colon cancer cell line and Human vein endothelial cells (HT-29 and HUVEC). Also, we performed the photothermal effects of these nanocomposites on cell proliferation and apoptosis using different biochemical staining. Our in vitro investigational datas are established rGO@Nar effectively exhibited and also with rGO@Nar + NIR the photothermal conversion therapy improved prostate cancer cells abolishing the cancer cells. More interestingly rGO@Nar + NIR was found to surpass the activity of rGO@Nar in colon cancer cells tested a topnotches. Thus, our study suggests that rGO@Nar + NIR could be used as impending anticancer candidate for photothermal ablation of prostate cancer cells. Further examinations of the mechanism indicated that anticancer activity was accomplished by inducing apoptosis in cancer cells.

Enhanced degradation performance of p-chlorophenol in photo-Fenton reaction activated by nano-Fe0 encapsulated in hydrothermal carbon: Improved Fe(III)/Fe(II) cycle

In this study, heterogeneous Fenton-like catalyst, nano-Fe° encapsulated in hydrothermal carbon (Fe°/HTCC), was prepared via a green chemistry route, aiming at increasing the degradation efficiency of p-chlorophenol (4-CP) by controlling the stability of the catalyst and Fe(III)/Fe(II) cycling in the advanced oxidation process. The degradation of 4-CP by heterogeneous Fenton reactions was conducted with the assistance of visible light, which was monitored with the aid of the HPLC and total organic carbon analysis. The results revealed that Fe°/HTCC composite markedly enhanced both the degradation (100 %) and the mineralization efficiency (∼73.9 %) for 100 mg/L 4-CP within 60 min at pH 4.0. More importantly, the catalyst presented a high stability to resist the side oxidation, where the removal efficiency was maintained even after 5 successive cycling experiments. Electron spin resonance confirmed that in the presence of both HTCC and visible light irradiation greatly enhanced the production of •OH for the degradation and mineralization of 4-CP, which can be attributed to the enhancement of Fe(III)/Fe(II) cycling. This study paves a new way toward the rational design of Fe°–carbon composites as heterogeneous Fenton-like catalysts for potential applications into wastewater treatment.

Rapid microwaving route for pseudocapacitive nanostructured polypyrroles

In present work, we report a direct one-pot microwave-assisted route for the much effusively explored conducting system: polypyrrole (PPy) bearing nanotubular morphology. The ratio of ‘fibrillar complex’ methyl orange/FeCl3 (soft-template) is marked as decisive synthesis parameter in shaping the material properties and potential applications of PPy(s) in supercapacitor technology. The nanosized PPys (diameter 10–50 nm) display good specific capacitance (118–215 F g−1) at 5 mV s−1 within a potential window −0.3 to 0.6 V as determined in 1 M KCl electrolyte. The optimized polymeric supercapacitor cell exhibits capacitance of 122 F g−1 at current density 0.5 A g−1 and energy density 12.47 Wh kg−1 at a power density of 214.56 W kg −1. The symmetrical cell retains 83.33% capacitance at a scan rate of 100 mV s−1 after running 3000 cycles suggestive of high durability. The research work bestows promising pseudocapacitive material for energy storage and opens up new frontiers in the field of ‘polymer chemistry’ via green chemistry routes.

Biogenic AgNPs—A Nano Weapon against Bacterial Canker of Tomato (BCT)

Bacterial canker of tomato caused by the bacterial pathogen Clavibacter michiganensis subsp. michiganensis (Cmm) is a major limiting factor for tomato production worldwide. Currently there exists no resistant variety of tomato to bacterial canker; only cultural and chemical controls are available. This study synthesized AgNPs (silver nanoparticles) via a green chemistry route and investigated their bactericidal potential against bacterial canker of tomato (BCT). AgNPs were prepared using mycellial aqueous extract of agriculturally beneficial fungi Pythium oligandrum. The formation of AgNPs was confirmed by using UV–Vis spectroscopy for the absorbance pattern while their morphology was investigated by the transmission electron microscopy (TEM). The X-ray diffraction profile for the biogenic AgNPs confirmed a crystalline structure with an average particle size of 12 nm. AgNPs treated seeds showed a normal germination rate with normal seedling growth. An in-vitro study found that the prepared AgNPs caused the maximum inhibition of the bacterial pathogen. In the greenhouse the introduction of AgNPs significantly prevents and inhibits the bacterial pathogen Cmm on tomato plants. These results suggest that this process is a strong candidate for industrial scale production of AgNPs. These particles act as an inhibitor and broad spectrum antibacterial agent against cmm, and hence offer a new and eco-friendly alternative in BCT control.

A case study targeting K fertilizer chemical synthesis with complete valorization of extraction by-products as an option

A green and sustainable chemical route to extract potassium and realize maximum utilization of potassium-rich silicate minerals.

Impact of Hibiscus extract on the structural and activity of sonochemically fabricated ZnO nanoparticles

In the present work, a green chemistry route for synthesizing zinc oxide (ZnO) nanostructures using Hibiscus extract as a stabilizing and a reducing agent under ultrasonic energy. The ZnO nanostructures obtained without (ZnO) and with Hibiscus extract (ZnO-H) were characterized to explore the effect of the plant extract on ZnO structure, morphology, and photocatalytic activity. The X-ray diffraction (XRD) data showed a reduction in ZnO crystallite size from 40 to 31 upon treatment with the Hibiscus extract. In addition, thinner ZnO nanorods were formed due to the use of the extract, as perceived from the scanning electron microscopic (SEM) analysis. The N2 physisorption data revealed that surface area and porosity increased with Hibiscus extract treatment, where the SBET increased from 4.0–10.0 m2. g−1, while the pore size and pore volume increased from 0.021 to 0.06 cm3. g−1 and 12.5–18.2 nm, respectively. The X-ray photoelectron spectroscopy (XPS) confirmed the formation of ZnO with minor shift in the binding energies as an effect of using the extract. As a consequence of band gap narrowing, surface area and porosity increase, the ZnO-H nanostructures exhibited better photocatalytic degradation performance for the methylene blue (MB) dye. The high efficiency for MB degradation was reflected by the higher photodegradation percentage and greater pseudo-first-order kinetics rate constant. The radical scavenger study revealed that superoxide radicals played a major role in the photodegradation of MB, especially over ZnO-H. The inexpensive, simple, eco-friendly approach of the previously described protocol for “one-pot” synthesis and alteration of ZnO characteristics could be expanded to fabricate other kinds of nanoparticles and to extend their utility in different areas of nanotechnology.