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Clean water, which is free from pathogens and toxic chemicals, is vital to human health. The blue planet is encountering remarkable challenges in meeting the ever-increasing demands of clean water. The intention of this research study was to develop a water filter material that is capable of removing bacterial contaminants and heavy metals from fresh water using cost effective and easily fabricated biocompatible filter material. For this purpose, granular activated carbon (GAC) was coated with both hydroxyapatite (HAP) nanoflakes and turmeric extract (TE) (HAP/TE/ GAC) which had been extracted from natural turmeric powder. In addition, GAC was coated only with HAP nanoflakes to synthesize HAP coated GAC (HAP/GAC) composite. Prepared HAP/GAC and HAP/TE/GAC were characterized using Fourier-transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy and UV-visible spectrophotometry. Antibacterial effect of the prepared nanocomposites, HAP/GAC and HAP/TE/GAC was compared with neat GAC using Gram-negative bacteria Escherichia coli. Results showed that antibacterial studies of the synthesized nanocomposites exhibit effective antibacterial activity against E. coli compared with neat GAC alone. However, the composite HAP/TE/GAC revealed better activity than HAP/GAC. Heavy metal adsorption ability of the synthesized composites was carried out using Pb2+ ions at room temperature at different time intervals and different pH levels. The equilibrium adsorption data were assessed via Langmuir and Freundlich adsorption isotherm models for neat GAC, HAP/GAC and HAP/TE/GAC at pH 6. The equilibrium adsorption data for GAC, HAP/GAC and HAP/TE/GAC were well fitted with both Freundlich and Langmuir isotherm models in the given Pb2+ concentrations. The HAP/TE/GAC composite is capable of maintaining the natural function of GAC in addition to removal of bacterial contaminants and heavy metals, which can be used as a point-of-use water filter material. [ABSTRACT FROM AUTHOR]

Synthesis of neat nano hydroxyapatite (HAp) was carried out using wet chemical precipitation methods at low temperature and this resulted rod like HAp nanocrystals with a diameter around 50–80 nm and length of about 250 nm. Impregnation of nano HAp onto the granular activated carbon (GAC) to prepare hydroxyapatite granular activated carbon nanocomposite (C-HAp) was carried out using in situ synthesis of nano HAp in the presence of GAC. The samples of neat nano HAp and C-HAp composite were characterized using Fourier-Transformed Infrared Spectroscopy (FT-IR), powder X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Detailed adsorption studies of neat nano HAp, C-HAp and neat GAC were conducted for Pb 2+ ions at room temperature at different pH levels. The adsorption data for Pb 2+ ions was evaluated according to both Langmuir and Freundlich adsorption isotherm models for both neat nano HAp and C-HAp separately at ambient temperature, 298 K. The equilibrium adsorption data were fitted well with Langmuir adsorption isotherm for neat nano HAp with an adsorption capacity in the range of 138–83 mg g −1 . For C-HAp nanocomposite the adsorption data were well fitted with Freundlich model and the calculated adsorption capacity was in the range of 9–14 mg g −1 . Leaching of Ca 2+ ions by neat nano HAp and C-HAp were also analyzed as a function of pH. It was found that the leaching of Ca 2+ was high in neat HAp than C-HAp. The leaching of Ca 2+ by neat HAp and C-HAp during adsorption of Pb 2+ ions were also investigated and revealed the lower percentage of leaching of Ca 2+ from the C-HAp nanocomposite when compared to neat nano HAp. [ABSTRACT FROM AUTHOR]

For the first time we report fabrication of a keratin protein based bio material for efficient removal of hazardous dye waste from water using merino wool fibers. Surface hydrolysed keratin protein fibers were prepared by subjecting merino wool fibers to controlled hydrolysis. During the hydrolysis the cuticle cells which sheath the hierarchical microstructure of the wool fibers were denatured. This has resulted in exposing ortho cortex of the fibers with comparatively higher degree of free amine and other surface functional groups which were confirmed by the SEM, EDX, AFM, FT-IR, NMR and CHNS analysis. The material showed exceptional adsorption capacities for carcinogenic Rhodamine B dye in the presence of acetic acid. Under optimized conditions, the surface hydrolysed keratin protein fibers showed ~95% of dye adsorption with maximum adsorption capacity of 294 mg/g at 298 K, in the presence of 3.5% acetic acid. This is the highest reported for the Rodhamine dye adsorption at similar conditions using other dye adsorption methods. Adsorption isotherm studies and Scatchard analysis of the isotherms were carried out to understand the binding mechanism of the dye molecules to the keratin protein fiber material. The main chemical attractions were found to be due to the free amine and carboxylic functionalities presence in the hydrolysed wool fiber material. Also it was observed to have charge induced adsorption and desorption which were driven mainly due to the protonation and deprotonation of the amine groups present in the keratin protein fibers. It is also confirmed that keratin protein fiber can be used for multiple times for adsorption of the dye molecules from an aqueous medium. Combining the high adsorption capacity and recyclability, surface hydrolysed keratin protein fibers prepared from merino wool can be a promising bio material to remove Rhodamine B dye from an aqueous medium modulated by acetic acid. Image 1 • Surface hydrolysed keratin protein fibers were prepared using merino wool. • Hydrolysed wool fibers showed exceptional adsorption of Rhodamine. • Equilibrium capacity is best aligned with the Langmuir isotherm model. • The keratin protein fibers showed an adsorption capacity of 294 mg/g at 298 K. • Up to now, the highest reported for the Rodhamine adsorption. [ABSTRACT FROM AUTHOR]