Noble metal nanoparticles (NMNPs) are viable alternative green sources compared to the chemical available methods in several approach like Food, medical, biotechnology, and textile industries. The biological synthesis of platinum nanoparticles (PtNPs), as a strong photocatalytic agent, has proved as more effective and safer method. In this study, PtNPs were synthesized at four different temperatures (25 °C, 50 °C, 70 °C, and 100 °C). PtNPs synthesized at 100 °C were smaller and exhibited spherical morphology with a high degree of dispersion. A series of physicochemical characterizations were applied to investigate the synthesis, particle size, crystalline nature, and surface morphology of PtNPs. The biosynthesized PtNPs were tested for the photodegradation of methylene blue (MB) under visible light irradiations. The results showed that PtNPs exhibited remarkable photocatalytic activity by degrading 98% of MB only in 40 min. The acid phosphatase mediated PtNPs showed strong bacterial inhibition efficiency against S. aureus and E. coli. Furthermore, it showed high antioxidant activity (88%) against 1,1-diphenyl-2-picryl-hydrazil (DPPH). In conclusion, this study provided an overview of the applications of PtNPs in food chemistry, biotechnology, and textile industries for the deterioration of the natural and synthetic dyes and its potential application in the suppression of pathogenic microbes of the biological systems. Thus, it could be used as a novel approach in the food microbiology, biomedical and environmental applications.

Nonsteroidal anti-inflammatory hydrophobic drugs (NSAIDs) are amongst the most commonly given categories of drugs worldwide in the treatment of pain, irritation and some of them even fever in many conditions. Critical micelle concentration of NSAIDs with Naproxen sodium (NS) and its mixture with non-ionic surfactants i.e. Tween 20, Tween 40 and Tween 60 was investigated at 293 K, 303 K, 313 K and 323 K at different concentrations using surface tension and dynamic laser light scattering (DLS) techniques. Due to amphiphilic behaviour in aqueous solution NS form aggregates at sufficiently high concentration. Thermodynamic/adsorption properties like free energy of micellization (ΔG_mic), enthalpy of micellization (ΔH_mic), entropy of micellization (ΔS_mic), Γ_mic and area per molecule (A₂) of NS in the presence of surfactants were also measured at different temperatures. The results showed that the presence of surfactants favoured the ΔG_mic and become more enhanced with increase in temperature. Further the solubility of drug is more favourable with increase in polyethylene chain in basic surfactant molecules i.e. 20–60, which indicates that Tween-60 enhanced the solubility of NS more comparatively to Tween-40 and Tween-20 and may be applied as best additive for solubilisation of NS.

The superabsorbent hydrogels (SAHs) are 3D polymer networks having hydrophilic nature, which can swell, absorb, and hold incredible amount of water in aqueous medium showing better sorption ability. The sorption ability enables SAH to absorb organic pollutants, dyes, and heavy metal ions (HMI) from wastewater. Therefore, SAHs have recently got considerable interest from the researchers to be used for wastewater treatment. In order to know the swelling property and to understand the wastewater treatment in general and heavy metal ion removal from industrial effluent in particular, this chapter describes the removal of heavy metal ions from wastewater in details. Thus this chapter will enable us to understand the theoretical and experimental part regarding the removal of heavy metal ions by SAH from wastewater. It also highlights the parameters of adsorption process such as effect of initial concentration of heavy metal ions, effect of external stimuli (pH), effect of temperature on the removal of heavy metal ions, and dosage studies. The synthesis of SAH and its use for removal of heavy metal ions from wastewater as well as recycling, selectivity, and effectiveness are also discussed in detail.