a b s t r a c tClay-alumina compositions of 0, 20, 40 and 55 weight percent (wt%) clay and rest alumina were maintained in porous support preparation by extrusion followed by sintering at 1300 • C for 2.5 h to obtain 3 mm/2 mm (outer diameter/inner diameter) capillary. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97%) (C8) was used to modify the capillary surface of all compositions without any intermediate membrane layer to impart hydrophobic characteristics and compared in terms of contact angle produced by the capillaries with water and liquid entry pressure (LEP w ). FTIR analysis showed that the hydrophilic surface of the capillary membranes was efficiently modified by the proposed grafting method. Capillary with 55 wt% clay produced a pore size of 1.43 micron and was considered as an ideal candidate for grafting with C8 polymer to impart surface hydrophobicity. The contact angle and LEP w value obtained for this modified membrane (C-55-M) were 145 • and 1 bar, respectively. The modified capillary membrane was applied for desalination of brine by air gap membrane distillation (AGMD) at a feed pressure of 0.85 bar. Maximum flux obtained for C-55-M membrane was 98.66 L/m 2 day at a temperature difference of 60 • C with salt rejection of 99.96%. Mass transfer coefficient of C-55-M was 16 × 10 −3 mm/s at feed temperature of 70 • C.
We report the fabrication and testing of a multilayer flexible screen-printed coil that can be used to generate low-frequency (<1 kHz) magnetic fields for applications such as electrodynamic wireless power transmission (EWPT). Compared to traditional coil-forming methods, screen printing enables rapid fabrication of thin, light weight, conformable, and flexible structures. The flexibility is demonstrated by repeated bending of a stack of up to three layers for a curvature (inverse bending radius) of 53.2 mm −1 . We also demonstrate wireless power transmission of 1 mW of power at a distance of 4 cm between the flexible receiver and transmitter. The effect of the flexibility is observed through a 32% power increase when the receiver is bent concavely and a 20% output power decrease when the stack is bent convexly. It is also seen that the insertion of a 0.2 mm-thick soft-magnetic material sheet increased the magnetic field by 41% from its original value. Mechanical cycling was also performed for the stack. After 10 000 bending cycles, a 16.4% increase in the coil resistance was measured for a 0.33 Hz frequency and 78% increase for a 1 Hz cycling frequency, respectively. Screen printed 3D flexible transmitter coils can enable the incorporation of EWPT for wireless charging in applications such as healthcare and consumer-based electronics.
Macro-porous pure alumina membrane was prepared from boehmite sol having a pH of 3.6 as a binder with alumina powder in different concentrations in weight percentage (2.5, 4 and 7 %) to make extrudable ceramic paste. The pastes were extruded by a plunger type extruder to 3/2 mm (outer/inner diameter) capillary tube. The capillaries were dried in a roller drier and subjected to retarded sintering at 1350°C for 2.5 h. Prepared membrane were characterized and compared with each other and membrane prepared with Methocel as organic binder for pore size, porosity, mechanical strength and clean water flux. The pore size of 7 % boehmite sol based membrane was found to be 400 nm when compared to 1.3 lm for membrane prepared with Methocel. The boehmite act as sintering agent and carry out the retarded sintering of alumina at 1350°C in place of 1700°C to form porous alumina membrane. Boehmite membrane was used for treatment of contaminated tannery wastewater and compared with membrane prepared from conventional organic binder. About 99 % removal in total organic carbon was obtained in case of boehmite membrane and chemical oxygen demand (COD) was reduced to 100 mg/L from an initial value of 6600 mg/L whereas in case of Methocel membrane COD was only reduced to 390 mg/L.
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