Electroreductive synthesis of polyfunctionalized pyridin-2-ones from acetoacetanilides and carbon disulfide with oxygen evolution

A chemical reductant or a sacrificial electron donor is required in any reduction reaction, generally resulting in undesired chemical wastes. Herein, we report a reductant-free reductive [3+2+1] annulation of β-keto...

Green Nanomaterials for Photocatalytic Degradation of Toxic Organic Compounds

In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of organic pollutants from tainted water using photodegradation, since the available chemical, physical, and biological methods often are time consuming, involve high cost and dumping complications, sometimes posing serious threat to both human health and environmental elements. Use of nanomaterials is less expensive and does not, in general, form aggregated macromolecules. In addition, nanotechnology for waste-water treatment demolishes or alters the risky chemical wastes to harmless end products like H2O and CO2. Nanomaterials synthesized from natural resources or prepared using green synthetic routes are receiving surge of interest as our consciousness to ecological environment and safety rises. ‘Green’ materials of this kind might also show unique strength features and exceptional biodegradability, along with their other notable advantageous properties like minimum threat to environment, efficient recyclablity and low cost compared to synthetic nanomaterials. Such green nanomaterials can also serve as nanocatalysts to treat toxic organic pollutants in a safer way, including photodegradation to less or non-toxic products. This article reviews latest developments on the synthesis of some promising green nanomaterials aiming towards their efficient uses as photocatalysts for degradation of organic pollutants. Strategies to find new green materials as photocatalysts by modification of technologies, and development of novel methodologies for safer treatment of organic pollutants will also be discussed.

Cyclohexanohemicucurbit[8]uril Inclusion Complexes With Heterocycles and Selective Extraction of Sulfur Compounds From Water

Solid-phase extraction that utilizes selective macrocyclic receptors can serve as a useful tool for removal of chemical wastes. Hemicucurbiturils are known to form inclusion complexes with suitably sized anions; however, their use in selective binding of non-charged species is still very limited. In this study, we found that cyclohexanohemicucurbit[8]uril encapsulates five- and six-membered sulfur- and oxygen-containing unsubstituted heterocycles, which is investigated by single-crystal X-ray diffraction, NMR spectroscopy, isothermal titration calorimetry, and thermogravimetry. The macrocycle acts as a promising selective sorption material for the extraction of sulfur heterocycles, such as 1,3-dithiolane and α-lipoic acid, from water.

Removal of agricultural wastewater pollutants by integrating two waste materials Fish scales and Neem leaves as novel potential adsorbent

Only 2.5 percent of the world's water is fresh, despite the fact that water covers approximately 70% of the planet. This water is used for several recreational purposes and gets polluted by wastewater disposal directly into freshwater bodies. Effluents dispersed into water bodies could be from various sources like industries, households, and agricultural activities. These effluents comprise heavy metals and chemical wastes directly released into water bodies without treatment and could include major contaminants like nitrates, nitrites, ammonia and phosphates. The present study mainly focuses on removal of four significant pollutants from agriculture wastes, i.e., nitrates, nitrites, ammonia, and phosphates. These pollutants are removed using adsorbents via a process known as adsorption. Adsorbents used in the study are fish scales and neem leaves. Several studies have been carried out to measure the efficiency of adsorbents in the removal of contaminants. These studies include equilibrium studies, kinetic studies and isotherm studies. Based on a complete analysis and results obtained, 95% to 99% of contaminants can be removed effectively with an adsorbent dosage of 0.4g (0.2 gms of fish scale and 0.2 gms of neem leaves powder), optimum pH of 6 and at 303K constant temperature. The dosage variance stems from changing the dosages of two adsorbents in three ways, i.e., by taking both adsorbents in equal dosages, and increasing the dosage of one adsorbent compared to the other and vice versa. The contact time varied from 0 to 140min and the Initial concentration of pollutants has also been varied from 30 to 70 mg/L. In addition to the above variations thermodynamic studies were also done and based on the negative values of ΔG, and positive value of ΔH and ΔS it is evident that the reaction of novel adsorbent (Combination of fish scales and neem leaves) is spontaneous and endothermic.

Self-Propulsion of Droplets via Light-Stimuli Rapid Control of Their Surface Tension

Biology demonstrates many examples of response and adaptation to external stimuli, and here we focus on self-propulsion (motion) while presenting several self-propelling droplet systems responsive to pH gradients. We use light as the gating source to gain reversibility, avoid the formation of chemical wastes, and control the self-propulsion remotely. To achieve light-stimuli ultra-fast response, we use photoacids and photobases, capable of donating or capturing a proton, respectively, in their excited-state. We control the movement and directionality of the droplet’s self-propulsion by introducing the photo-acid/base either in bulk solution, on the surface of the droplet, or inside the droplet. We show that proton transfer between the photo-acid/base and the droplet results in a rapid change in the droplet’s surface tension, which induces the self?propulsion movement. The high versatility of our systems together with a record-breaking ultra?fast response to light makes them highly attractive for the design of various controlled cargo?carrier systems.<br>

Self-Propulsion of Droplets via Light-Stimuli Rapid Control of Their Surface Tension

Biology demonstrates many examples of response and adaptation to external stimuli, and here we focus on self-propulsion (motion) while presenting several self-propelling droplet systems responsive to pH gradients. We use light as the gating source to gain reversibility, avoid the formation of chemical wastes, and control the self-propulsion remotely. To achieve light-stimuli ultra-fast response, we use photoacids and photobases, capable of donating or capturing a proton, respectively, in their excited-state. We control the movement and directionality of the droplet’s self-propulsion by introducing the photo-acid/base either in bulk solution, on the surface of the droplet, or inside the droplet. We show that proton transfer between the photo-acid/base and the droplet results in a rapid change in the droplet’s surface tension, which induces the self?propulsion movement. The high versatility of our systems together with a record-breaking ultra?fast response to light makes them highly attractive for the design of various controlled cargo?carrier systems.<br>

Bioremediation Techniques for Polluted Environment: Concept, Advantages, Limitations, and Prospects

Environmental pollution has been rising in the past few decades due to increased anthropogenic activities. Bioremediation is an attractive and successful cleaning technique to remove toxic waste from polluted environment. Bioremediation is highly involved in degradation, eradication, immobilization, or detoxification diverse chemical wastes and physical hazardous materials from the surrounding through the all-inclusive and action of microorganisms. The main principle is degrading and converting pollutants to less toxic forms. Bioremediation can be carried out ex-situ and in-situ, depending on several factors, which include but not limited to cost, site characteristics, type, and concentration of pollutants. Hence, appropriate bioremediation technique is selected. Additionally, the major methodologies to develop bioremediation are biostimulation, bioaugmentation, bioventing, biopiles, and bioattenuation provided the environmental factors that decide the completion of bioremediation. Bioremediation is the most effective, economical, eco-friendly management tool to manage the polluted environment. All bioremediation techniques have its own advantage and disadvantage because it has its own specific applications.

A short review of titania-graphene oxide based composites as a photocatalysts

New and effective methods of water purification are necessary to minimize pollution. Many methods have been used in wastewater treatment, but sorption is considered as an easy and economic process. The efficiency of any sorption process mainly depends on the physicochemical properties of the used adsorbent. Since photocatalysts can initiate reactions of decomposition organic contaminants under ultraviolet or sunlight irradiation without using chemicals or producing chemical wastes, photocatalytic reactions are considered a sustainable way to remove a variety of environmental pollutants. Ultraviolet water purification became the most effective method of water disinfection and purification. Heterogeneous semiconductor photocatalysts have recently emerged as an efficient material for purifying water. The crystal structure is crucial for photocatalytic activity and efficiency of semiconductors, thus optimal parameters must be provided during the preparation of photocatalysts. To overcome problems with semiconductors usage, the use of co-catalysts and photocatalyst carriers is one of the solutions. Recently, much emphasis has been placed on using graphene oxide (GO) supported semiconductor photocatalysts. In this paper, a short review of composites of titanium dioxide and graphene oxide-based materials is given.

Decarbonylative Synthesis of Aryl Nitriles from Aromatic Esters and Organocyanides by a Nickel Catalyst

A decarbonylative cyanation of aromatic esters with aminoacetonitriles in the presence of a nickel catalyst was developed. The key to this reaction was the use of a thiophene-based diphosphine ligand, dcypt, permitting the synthesis of aryl nitrile without the generation of stoichiometric metal- or halogen-containing chemical wastes. A wide range of aromatic esters, including hetarenes and pharmaceutical molecules, can be converted into aryl nitriles.