Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

The biological properties of dietary polyphenols are greatly dependent on their bioavailability that, in turn, is largely influenced by their degree of polymerization. The gut microbiota play a key role in modulating the production, bioavailability and, thus, the biological activities of phenolic metabolites, particularly after the intake of food containing high-molecular-weight polyphenols. In addition, evidence is emerging on the activity of dietary polyphenols on the modulation of the colonic microbial population composition or activity. However, although the great range of health-promoting activities of dietary polyphenols has been widely investigated, their effect on the modulation of the gut ecology and the two-way relationship "polyphenols ↔ microbiota" are still poorly understood. Only a few studies have examined the impact of dietary polyphenols on the human gut microbiota, and most were focused on single polyphenol molecules and selected bacterial populations. This review focuses on the reciprocal interactions between the gut microbiota and polyphenols, the mechanisms of action and the consequences of these interactions on human health.

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Benefits of polyphenols on gut microbiota and implications in human health.

Electrospinning of polymeric nanofibers for drug delivery applications

Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

Introduction to Spectroscopy

Increasing public awareness of environmental pollution influences the search and development of technologies that help in clean up of organic and inorganic contaminants such as hydrocarbons and metals. An alternative and eco-friendly method of remediation technology of environments contaminated with these pollutants is the use of biosurfactants and biosurfactant-producing microorganisms. The diversity of biosurfactants makes them an attractive group of compounds for potential use in a wide variety of industrial and biotechnological applications. The purpose of this review is to provide a comprehensive overview of advances in the applications of biosurfactants and biosurfactant-producing microorganisms in hydrocarbon and metal remediation technologies.

https://www.mdpi.com/1422-0067/12/1/633/pdf

Environmental applications of biosurfactants: Recent advances

Treatment of textile wastewater by homogeneous and heterogeneous Fenton oxidation processes

Aims: The aim of the present study was to investigate the anti-Streptococcus mutans activity and the in vitro effects of subminimal inhibitory concentrations of guaijaverin isolated from Psidium guajava Linn. on cariogenic properties of Strep. mutans.



Methods and Results:  Bioautography-directed chromatographic fractionation, yield biologically active compound, quercetin-3-O-α-l-arabinopyranoside (guaijaverin), from crude methanol extract of P. guajava. Growth-inhibitory activity of the compound against Strep. mutans of both clinical and type strain cultures was evaluated. The anti-Strep. mutans activity of the guaijaverin was found to be bacteriostatic, both heat and acid stable and alkali labile with the minimum inhibitory concentration (MIC) of 4 mg ml−1 for MTCC 1943 and 2 mg ml−1 for CLSM 001. The sub-MIC concentrations (0·0078–2 mg ml−1) of the guaijaverin were evaluated for its cariogenic properties such as acid production, cell-surface hydrophobicity, sucrose-dependent adherence to glass surface and sucrose-induced aggregation of Strep. mutans.



Conclusions:  The active flavonoid compound, quercetin-3-O-α-l-arabinopyranoside (guaijaverin) demonstrated high potential antiplaque agent by inhibiting the growth of the Strep. mutans.



Significance and Impact of the Study:  This study demonstrated the new growth-inhibitory compound guaijaverin against Strep. mutans and led to the acceptance of traditional medicine and natural products as an alternative form of health care.

Guaijaverin -- a plant flavonoid as potential antiplaque agent against Streptococcus mutans.

Healing potential of Datura alba on burn wounds in albino rats.

Fabrication of nanofibrous biomaterials based on natural materials (collagen, gelatin, etc.) through various techniques is an important research topic. Electrospinning, a well-established technique for nanofiber production has also been extended for producing nanofibrous structures of natural materials. Collagen nanofiber production utilizes hexafluoro isopropanol (HFIP) as a solvent for electrospinning. Research efforts are now focused on replacing HFIP with an environmentally benign solvent. In this study, electrospinning of Type I collagen of bovine skin with polycaprolactone (PCL) as a blend and an environmentally benign solvent, acetic acid, was carried out. The samples produced were subjected to contact angle measurements, porosity estimation, SEM, FTIR, TGA, and DSC. Nanofibers in the range of 100–200 nm were produced with an optimum porosity of 60%. The instrumental analyses confirm the physical interaction between collagen and PCL. Electrospinning of collagen in an environmentally benign solvent has been carried out and its usage in tissue engineering is being investigated by our research group. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Electrospinning of type I collagen and PCL nanofibers using acetic acid

Hides and skins, by-product of the meat industry is converted into a value added product namely leather by the tanners. Tanning essentially is the process of converting raw hides and skins into imputrescible substance. The tanning process has number of steps and generates significant quantities of by products and wastes. These solid and liquid wastes pose major environmental problem if not managed effectively. Large–scale production systems are adopted for leather processing in clusters and therefore, the industry receives focus of environmentalists and society. Consequently tremendous pressure is exerted by various pollution regulatory bodies. The hides and skins, after trimming, removal of flesh and fat, are treated with chemicals, which cross-link the collagen fibers to form a stable, durable material. The chemicals used may be derived from traditional vegetable products, or inorganic metal salts. During leather processing number of size reduction, leveling and purification operations are carried out which results in generation of untanned and tanned proteinous waste materials. In this paper, various recovery processes and utilization methodologies of proteinous solid wastes, emanating from leather processing operations prior to tanning is reviewed.

Arumugam Gnanamani

Papers

Treatment of textile wastewater by homogeneous and heterogeneous Fenton oxidation processes

Guaijaverin -- a plant flavonoid as potential antiplaque agent against Streptococcus mutans.

Healing potential of Datura alba on burn wounds in albino rats.

Electrospinning of type I collagen and PCL nanofibers using acetic acid

Recovery and utilization of proteinous wastes of leather making: a review