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.

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.

No abstract

No abstract

The effect of incorporating Zr0 2 and TiC on different mechanical properties as well as the performance of alumina based ceramic cutting tools has been studied. Along with the mechanical properties of the tool materials, the importance of tool geometry and the effect of different cutting parameters, viz. cutting speed, feed and depth of cut, on the tool life have also been discussed. It was observed that these tools were useable successfully even at a cutting speed of 350 m/min and up to that limit, the increase in cutting speed had a slightly negative effect on their performances while the wear rate was found to be more sensitive to the variation of depth of cut. Addition of TiC and Zr0 2 improved their performances for the applications requiring very high speed and high depth of cut respectively.