Mini-Reviews in Organic Chemistry - Volume 18, Issue 4, 2021

The leather industry is an essential sector, especially in countries with highly developed livestock as they use rawhide to produce high-valued leather products. The leather-making process uses different chemicals and is a source of environmental pollution if the wastewater is not properly treated. Therefore, the purpose of this study is to analyze a Moving-Bed Biofilm Reactor (MBBR) as a new technology for the biological treatment of tannery wastewater. This system incorporate benefits provided by the suspended growth systems, which have already been consolidated in treating wastewater, such as activated sludge and the advantage of growth adhered to biocarriers that have a large surface area. Incorporating activated sludge into MBBR enables the removal of both organic and nitrogen pollutants. Studies have shown that MBBR treatment efficiency depends on biocarrier surface area, composition, texture, and reactor operating conditions, such as filling fraction, hydraulic retention time, dissolved oxygen, and volumetric organic load.

Sewage sludge shows excellent potential as pyrolysis feedstock in generating valuable products such as Activated Carbons (ACs). In this mini-review the preparation of sewage sludge- ACs by two kinds of pyrolysis conventional and microwave heating is presented and discussed. The main difference between conventional pyrolysis and the microwave-assisted method is the way the heat is generated, and both can provide ACs with different textural and chemical properties. Based on what was demonstrated in this work, it is possible to say that both kinds of pyrolysis (microwave and conventional methods) can produce high specific surface area and efficiently activated carbons from sewage sludge. It was also demonstrated that sludge-ACs produced by both pyrolysis methods could reach very high uptakes of pharmaceuticals from aqueous solutions. The van der Waals interactions, hydrogen bonding and π-π interactions of the aromatic ring of the adsorbent with the aromatic rings of the pharmaceuticals have been mentioned to be some of the main mechanisms governing the pharmaceuticals adsorption by ACs.

Continuously growing environmental issues have become a significant problem in the world. These ecological issues deteriorate our day to day life and are responsible for serious diseases. Also, the growing industrialization of the world has steeply risen and demanding petroleum products for their modernization. Economic development has also resulted in a considerable rise in energy demand. Biodiesel, a less polluting and sustainable fuel replacing diesel, has been gaining significant attention from researchers from all over the world. The utilization of vegetable oil and waste oil as fuel is found to be less polluting than the petrochemical products. The fundamental problem in biodiesel production is that it is more susceptible to oxidation, which results in increased viscosity of biodiesel concerning time, which in turn creates the problem. Therefore this review paper is focused on the current fossil fuel scenario concerning with respect to World and India along with the properties of biodiesel resources and its production processes.

In their search for an alternative to commercial adsorbents, much research is turned to the local biomass-based materials such as agricultural residues and assimilated derivatives. However, natural biomass due to its low specific surface area must first undergo several pre-treatments. Among the newly emerging electric techniques for environmental applications, those who operate at atmospheric pressure (Non-thermal plasma) have recently found many breakthrough applications arising from their easy use with no extra additional reagents and their high reactivity. The Non-thermal plasma treatment of biomass is one of the promising developed approaches mainly due to significant effects including the formation of micro and macrospores, the increase of surface roughness, and surface functionalization. The most used plasma is non-thermal, so as not to denature the biomass, likewise the hot plasma can burn and/or destroy high contains carbon biomaterials. Especially, the gliding arc plasma obtained using moisten air as feeding gas, which is known to induce acidifying and oxidizing effects in an aqueous target. The primary species HO• radicals [E° (HO•/H2O) = 2.85 V/SHE] mainly formed in the arc will be with the dimer H2O2 [E°(H2O2/H2O) = 1.76 V/SHE] the determining agents for the chemical reactions induced. Exposure of a target to this kind of environment is likely to promote great surface transformations. This approach has some advantages: (i) the merit of not using commercial chemical reagents, the reactive species being in situ generated; (ii) the risks related to the manipulation of the products, the plasma reactor is robust and can be modulated to treat large quantity; (iii) the efficiency of the bi-functionality of the plasma (acidifier and oxidative). In this review, we will highlight the main changes induced by exposure of biomass to plasma treatment and also make a comparative study between chemically and plasma-activated materials in the removal of various pollutants from aqueous solution; and finally, we summarize the findings in the existing literature.

Considering the global environmental issues, various factors such as industrial ecology, eco-efficiency, and chemical engineering are being combined to develop advanced material known as bio-based or natural polymer-based materials. The environment and the cost-effective factors are now propelling the inclination in the direction of greater utilization of bio-based polymers and materials. Biobased materials are generally used to make industrial products and reliable goods. They are composed of a natural polymer, reinforced with agricultural waste, natural fibres and carbohydrates like starch, lignin, and cellulose. In this paper, we have discussed the introductory part of the biopolymers, e.g., cellulose, chitin, chitosan, PLA, and soy protein. Also, the mechanical properties of composites developed by using these biopolymers and their applications, specifically in the areas of biomedical and packaging sectors, have been discussed.

Biochar-Amended Composting (BAC) plays an integral role in sustainable agricultural practices due to its multiple benefits in crop production, soil nutrient retention, carbon sequestration and environmental protection. Although accepted as a traditional method, there is a lack of understanding in defining its suitability and efficiency in terms of various base-materials and conditions. Being two carbon-based entities with plentiful nutrients and surface activity, biochar and compost find application in agricultural fields together or separately for improving the soil properties and crop productivity. Recent studies focus on defining the optimum conditions for their preparation, mixing, application and monitoring under various feed, soil, crop and climatic conditions. However, due to the complexity and specificity of the system, many influencing aspects of their interaction are yet unknown in detail. In this review, we analyze the recent advancements in the selection and preparation of new materials for BAC, and explain the mechanisms of Organic Matter (OM) degradation/sequestration occurring in soil based on possible chemical/morphological transformations of organic carbon. Most of the performance results are in agreement with the previous records, but a few contradictions have been observed under diverse experimental conditions. In general, BAC enhanced the mineralization of carbon and sequestration of heavy metals, and stabilized labile fraction of OM due to the development of carbonyl, phenolic and aromatic functional groups on its surface. In addition, aging of biochar resulted in stable N-C=O and amino groups for the adsorption of nitrogen compounds thus decreasing the potential greenhouse gas emissions. The study further identifies potential future research gaps in this area.

Ascidians (tunicates) are widely recognized as one of the most prolific producers of bioactive natural products in the marine environment. This present study reviewed the chemical diversity of marine ascidians from the Aplidium genus and their pharmacological applications since Jan 2005. The resources of this genus from China Seas, including the changes of their names in the family Polydinidae were also summarized in this paper. In addition, a concise outlook on their chemical and pharmaceutical investigation is made to support further development.

Calixarenes are macrocyclic compounds that form complexes with ions and neutral molecules. Association with ammonium cations and calixarenes is directed by coulombic forces, hydrogen bonding, N+-C-H---π interactions and van der Waals interactions. Calixarenes are stronger acids than corresponding phenols and react with aliphatic amines by proton-transfer and the ammonium cations can be placed as exo or endo-calix. The type of aggregate and the association constants are related to the branching of the chain, the basic character of amine, and the size of the calix. Trimethylammonium cations, like choline, bind sulfonate calix[4 and 6]arenes and calix[6]arenes by coulombic and N+-C-H---π interactions. Interaction of calixarenes and ammonium cations has been used for biological sensors for neurotransmitters and peptide hormones.

The diverse library of biologically active organic compounds is composed majorly of heterocyclic compounds. Nature provides a variety of pharmacologically active compounds consisting of N-heterocycle motif, such as Noscapine (anti-cancer), Morphine (analgesic), Chelerythrine (antibacterial), etc. which are the elementary structural units of marketed drugs in the present era. One such “N-heterocyclic” promising building block which has gained the attention of chemists is Pyrazinoindoles and the inflating interest in this moiety is a result of the three-fused heterocyclic ring structure subsuming an indolic nucleus in it. Fused-polycyclic structural core is necessary to synthesize potential multi-functional drugs, which is evident from indole (an example of fused five and sixmembered ring structure) being an exemplary and established privileged template in medicinal chemistry. In the literature, Pyrazino-fused indoles have been found documented regarding their biological activities and therapeutic uses, particularly as antifungal, antibacterial, serotonergic receptor inhibitor, central nervous system depressants, anticonvulsants, antihistaminic, protein kinase C inhibitors, anti-depressants and so on. Although various synthesis strategies are available in the literature, yet the medical relevance of the Pyrazinoindoles demands the development of versatile and simple novel methodologies. This review features a comprehensive overview of the recent developments in synthetic approaches and therapeutic applications of Pyrazinoindoles based scaffolds.

Cosmeceuticals are cosmetic products containing biologically active ingredients with attractive properties (e.g. anti-oxidant, anti-inflammatory, anti-aging, photoprotective activity, etc.). The aim of these compounds is to offer pharmaceutically therapeutic benefits. The active ingredients can be extracted and purified from natural sources, including plants and animals, or be obtained by biotechnological methodologies (e.g. fermentation, enzymatic synthesis, etc.). Recent years have been increased interest in the design and development of bioactive compounds with cosmeceutical applications and low toxicity. The enzymatic synthesis of bioactive esters, based on esterification or transesterification, has attracted much interest because of the interesting properties of the resulting products and because, by replacing traditional chemical catalysts, this approach leads towards the development of more sustainable processes that follow the principles of Green Chemistry. This review gives an overview of the excellent suitability of lipases as biocatalysts for producing bioactive compounds with attractive properties for the cosmetics industry.

As a medicinal fungus, Inonotus obliquus (IO) has been widely used in the treatment of cancer and digestive system diseases. Despite the progress that has been made in the studies of IO and its active compounds, their applications in the treatment of other important clinical diseases, such as cardiovascular diseases, which are major global issues with limited treatment strategies, are seldom reported. This review summarizes the separation and purification methods of chemical components of IO, the advances in their applications, and research progress on the pharmacological effects and related mechanisms of IO in disease prevention. This review will help researchers and clinicians to further understand the pharmacological functions and mechanisms of IO and its active components, which may extend their medical applications in the prevention and treatment of other diseases in addition to tumors and digestive system diseases in the near future.