IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Development of high performance pervaporation desalination membranes: A brief review
No full textWater scarcity rises as the level of water pollution continues to increase with the progress of urbanization, industrialization and exponential growth of population. Therefore, saline water of the sea should also be made suitable rather than river water to meet the huge global demand of clean and safe drinking water. Pervaporation (PV) desalination, among many purification and separation processes, is a promising technology to reduce the crisis of global drinking water supply. From this perspective, the key success of PV desalination relies on its remarkable salt rejection from highly saline water with appropriate flux to obtain fresh water by using a suitable membrane. In this review we aim to provide a comprehensive assessment of PV desalination membrane materials, transport phenomena, the advantages of the process over comparable technologies (e.g., fractional distillation, membrane distillation, reverse osmosis) and the advantages of crosslinking during the preparation of composite membranes. This review further highlights the advantages of inorganic ceramic substrates as a support of composite membranes and the use of hydrophilic polymers as active layer for preparing stable and robust crosslinked PV desalination membranes.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved
Green synthesis of hierarchically structured Ag-Cu2O on cotton fabric with sustained antimicrobial activity and on-demand oil-water separation ability
No full textFilm deposition/modification of cotton fabric surface is an effective way to impart multiple functionalities towards a broad range of applications. In this work, we demonstrate a facile approach for the green fabrication of hierarchical hollow structures of Ag-Cu2O on cotton fabric (ACN). The effect of key parameters such as time, temperature, precursor concentrations, and type of substrates upon the formation of a unique mud-dauber wasp nest-like structure has been studied and also the formation mechanism of the structure has been proposed. The fabric shows underwater superoleophobicity owing to the presence of hierarchical surface structures and after modification with hexadecyltrimethoxysilane (ACNS), it also shows superhydrophobicity. By virtue of switchable super-wettability, the fabric has been used for on-demand separation of light oil-water and heavy oil-water mixtures with similar to 99% separation efficiency and superior reusability. In addition, the coated fabric, ACNS exhibits an excellent self-cleaning ability towards solid and liquid contaminants. Moreover, the coated fabric, ACN shows antimicrobial activity towards bacteria E. coli and S. aureus and fungi C. albicans with 100% microbial reduction efficiency. The superhydrophobic cotton fabric (ACNS) has been employed to enhance the longevity of antimicrobial activity by hindering the uninhibited release of copper and silver ions. As a result, an efficient and sustainable antimicrobial activity up to 90 days has been achieved. This modification strategy could be useful for advancing research in the field of surface science
Influence of temperatures on structure, thermoelectric, and mechanical properties of nanocrystalline SnSe thin films deposited by thermal evaporation
No full textThe Tin Selenide (SnSe) thermoelectric materials' high heat-electricity inter-conversion capability makes it a potential energy resource material to tap the waste heat from different industrial processing. The present work has optimized parameters for the deposition of single-phase nanocrystalline SnSe thin films using the thermal evaporation technique. The XRD, Raman Spectroscopy, SEM, EDS, Seebeck Coefficient, Electrical Conductivity, and Thermal Conductivity data analyses were used to optimize and establish the structure-thermoelectric property relationship for nanocrystalline SnSe films. The phase analysis of the SnSe thin films deposited at various substrate heating temperatures (Ts) reveals a significant influence of Ts in the evolution of a single phase of SnSe film. The films deposited at Ts & LE; 200 C evolved with the phases of Sn, Se, and SnSe, whereas films deposited at Ts & GE; 300 C grew with single-phase polycrystalline SnSe. An increase in crystallite size with a shape transformation from circular to elongated grains was observed with Ts. The maximum ZT value of 0.64 with a power factor value of-2.2 mu Wcm-1K-2 at 750 K measuring temperature (Ta) was obtained for the SnSe film deposited at Ts = 300 C. The change in thermoelectric properties with Ta, including a p-type to n-type transition observed at-600 K, was correlated with the alteration of structure and the elemental composition of the deposited films after heating at 350 C. The heating temperature significantly influenced the hardness and elastic modulus values of the films deposited at Ts & LE; 300 C
N‑Doped Fluorescent Carbon Nanosheets as a Label-Free Platform for Sensing Bisphenol Derivatives
No full textIn this paper, we report the synthesis of fluorescent
carbon nanosheets from carbon nanoparticles produced from the burning of oil. This has been achieved by nitric acid oxidation, which initiates the sheet formation. We performed a detailed study of the formation mechanism, which revealed that this oxidation technique stitches the small carbon nanoparticles into a large sheet via nitrogen defect incorporation, which, in turn, introduces strain
in the nanosheet through pyridinic or pyrazolic ring formation. The synthesis technique also introduces several oxygenated surface functional groups, which provide excellent colloidal stability to the nanosheets. Nitrogen incorporation also assists in generating strong greenish-yellow fluorescence with ∼15% quantum yield. A comprehensive study of the fluorescence origin reveals that this emission has two different origins: one originating from the excitation wavelength-dependent conjugation of sp2 clusters in the sp3 backbone and the other originating from the fixed n−π* transition of oxygenated and nitrogenated defect states, which is excitation wavelength-independent. These nanosheets are several microns in length and ∼1 to 2 nm in thickness. We explored the application of these nanosheets for label-free sensing of bisphenol derivatives as organic molecules and found that they can interact with the π-ring structures of the nanosheets. Interestingly, bisphenol derivatives interact selectively with the nanosheets, creating a blue shift of the emission spectra. In addition to the high selectivity for bisphenol detection, the detection limit was found to be as low as a few
nanomolar (limit of detection (LOD) ∼0.3 nM)
Technical Assessment of Terracotta Clays Used by Rural Potters in Gujarat
No full textGujarat has about 5000 families engaged in the manufacturing of terracotta pottery. A Survey of rural potters and characterization of their terracotta raw materials carried out in Integrated Pottery Development Project (IPDP) revealed a lot of important technical information regarding terracotta manufacturing. Traditional handicraft rural pottery in Gujarat is faced with range of technical problems related to its manufacturing process. The pond clay and farm clay used by rural potters are soils. Main clay minerals in these soils are kaolinite, muscovite-illite, and Smectites associated with quartz, goethite, feldspars, and anatase. Black soil is the most dominant soil type in Gujarat. The main parent rocks in red soils are crystalline and metamorphic rocks like acid granites, gneisses and quartzites. The red soils are mostly loamy and hence cannot retain water like the black soils. The red colour is more due to the wide diffusion rather than the high percentage of iron oxide content.Alluvial clays were easily available near the rivers, sea, and ponds and are natural body mixes suitable for throwing. The potters residing in areas short of alluvial clays utilize mixtures of black soils and red soils. Plastic and dry properties of black, brown and red terracotta clays from Gujarat showed an increasing trend along with increase in particle fineness. Major shrinkage of terracotta products takes place during the drying process only. Firing shrinkage at 800°C is very less and no consolidation of material takes place during firing. Porosity is increased due to the burning of organic matter and evaporation of mechanical and chemical waters. The average water absorption remains in the range of 14 to 16% when fired at 800°C. Terracotta clays undergo irreversible changes when fired above 600°C. Black terracotta clays have a significant amount of calcite and higher Na2O content causing them to bloat when fired at higher temperatures. A higher quantity of calcite in black clays is also responsible for higher drying and firing rejections
Multimode Mamyshev oscillator
No full textWe present a spatiotemporally mode-locked Mamyshev
oscillator. A wide variety of multimode mode-locked states,
with varying degrees of spatiotemporal coupling, are
observed. We find that some control of the modal content
of the output beam is possible through the cavity design.
Comparison of simulations with experiments indicates that
spatiotemporal mode locking (STML) is enabled by nonlin-
ear intermodal interactions and spatial filtering, along with
the Mamyshev mechanism. This work represents a first, to
the best of our knowledge, exploration of STML in an oscil-
lator with a Mamyshev saturable absorber
Symbiotically Augmented removal of Congo red by polyaniline/cobalt sulfide/graphite composites
No full textThe presence of Congo red dye (CR) in industrial sewage causes a serious threat to the environment. Therefore, it is imperative to develop high-performance, low-cost functional materials to mitigate such issues. During past decades, polyaniline and its composites have been recognized as an emerging candidate to remove hazardous organic effluents from water. The present work demonstrates the successful elimination of CR from water in presence of newly synthesized graphite/cobalt sulfide/PANI-based ternary composites. Several morphological or physicochemical characterization tools were adopted to confirm the formation of the ternary composite and subsequent synergistic interaction between individual elements of the composites. The experimental results delineate that a maximum of similar to 95.55% CR removal (%) was achieved after 120 min. Fast removal (similar to 5-10 min) of CR dye is observed for APS/Ternary composite system. From the fitted experimental data utilizing 1st or 2nd order rate kinetic models, it was observed that the adsorption induced degradation of CR dye and the process was chemisorptions in nature. Further, an intra-molecular diffusion model was also introduced that signifies both boundary layer diffusion or intraparticle diffusion phenomenon was responsible for CR removal. Furthermore, the cytotoxicity profile of the composite treated Congo red aqueous solution was evaluated when exposed to L929 fibroblast cells after 24 h or 72 h of exposure and the result deciphers the non-toxic nature of composite treated CR water
White light phosphorescence from ZnO nanoparticles for white LED applications
No full textWhite light emission from a pristine, solid material is currently the biggest challenge in the lighting industry. In this paper we report for the first time highly reproducible, stable, and intense white phosphorescence (similar to 4-32 mu s) from phase-pure zinc oxide (ZnO) nanopowder synthesized by a simple, low temperature process. The structure and morphology were studied by XRD, FESEM, and TEM. The white light consisted of narrow blue (centered at similar to 425 nm) and broad yellow-orange (centered at similar to 625 nm) photoluminescence and the best result was observed at (0.36,0.33) in the CIE plot. The presence of zinc interstitial (Zn-i) and oxygen interstitial (O-i) defects responsible for such white phosphorescence was confirmed by EDX, XPS, and Raman studies. The visibly bright white emission has appreciable quantum yield (similar to 12-14%) and cool/near cool correlated color temperature, rendering it suitable for W-LED applications. Further, a defect chemistry-based thermodynamic interpretation was invoked to adequately explain the white emission
Nanoscale plasticity in titania densified alumina ceramics
No full textThe present study explores the physics behind the loading rate (dP/dt or P asymptotic to 1 - 1000 mN s(-1)) dependent nanoscale plasticity (NSP) events observed during carefully controlled nanoindentation (NI) experiments on 1, 3, and 5 wt. % Titania Densified Alumina (TDA) ceramics. Characterizations of the TDA ceramics are carried out by x-ray diffraction, field emission scanning electron microscopy (FESEM), and NI techniques. A significant enhancement (similar to 30%) of the nanohardness of TDA ceramics occur with an enhancement in P . The results confirm that both the critical load (P-c) at which micro-pop-in or the NSP events initiate and the corresponding critical depth (h(c)) are sensitive functions of relative density, size of relatively finer grains, loading rate, and the amount of sintering aids. The experimentally observed empirical power law dependence of all the NSP related parameters on P is rationalized theoretically and qualitatively. It is suggested that the shear induced homogeneous dislocation nucleation underneath the nanoindenter may be the main factor contributing to the occurrence of the NSP events at relatively lower loading rates. However, especially at the relatively higher loading rates, the FESEM based evidence and the data obtained from the related NI experiments suggest that there is a more acute interconnection between the homogeneous dislocation nucleation induced profuse occurrence of the NSP events, shear band formations, and microcrack formation in the TDA ceramics. Finally, the design implications of the present results for the development of better alumina ceramics for load and strain tolerant applications are discussed.& nbsp;Published under an exclusive license by AIP Publishing
Heavy metal recovery from electroplating effluent using adsorption by jute waste-derived biochar for soil amendment and plant micro-fertilizer
No full textEffluent from electroplating industries contains various toxic heavy metal ions such as chromium, nickel, lead, cadmium, copper and zinc. Recovery of the valuable heavy metals by environment friendly approach for recycling in various useful applications could be significant from the perspectives of clean process development with techno-economic viability. Zinc is an important component of electroplating effluent found in high concentration (80-750 mg/L). The present study investigates on recovery of zinc from electroplating effluent using an efficient biochar synthesized from jute industrial wastes. Biochar characteristics and metal removal mechanisms were established using BET surface area, zeta potential, FESEM-EDAX, elemental mapping, XRD, FTIR, XPS, XRF, Raman spectroscopy and roles played by functional groups. Optimum adsorption capacity of 526.32 mg g(-1) was obtained for Zn(II). Zn(II) binding was achieved by ion exchange, complexation with functional groups, electrostatic interactions, adsorption and micro-precipitation. The techno-economic analysis was performed for biochar prepared by chemical carbonization process and found competitive in comparison with other reported biochar obtained by slow pyrolysis process. Further, the disposal of the toxic metal-laden spent adsorbent is a critical issue that needs to be addressed. In the present study recycling potential of the exhausted Zn(II)-laden biochar was explored for the development of micro-fertilizer for plants and soil-fertility improvement. Application of the Zn(II)-laden biochar mixed with soil revealed a positive influence on Cicer arietinum seed germination, plant growth parameters, protein and chlorophyll a and b content. Significantly, there were no changes in the antioxidant enzymes activities, superoxide dismutase (SOD) and catalase (CAT) between the plants grown in control soil and different Zn(II)-laden biochar-mixed soil, suggesting that 15% of the Zn(II)-laden biochar could not be excess condition of zinc. The present study thus addresses an important aspect of solid waste management of jute industry considering significant volume of jute waste production of similar to 0.04 MT/day in India along with the remediation of electroplating and other metal-bearing industrial effluent. Further, micro-fertilizer application of the metal-laden sludge and soil productivity improvement at low cost, environmentally safe and fruitful manner makes the study significant from ecological as well as societal perspectives. GRAPHICS]