Venkatram Reddy | CSMCRI, Bhavnagar (original) (raw)
Papers by Venkatram Reddy
Journal of Membrane Science, 2008
Novel composite nanofiltration membranes containing aromaticcycloaliphatic polyamide skin layer ... more Novel composite nanofiltration membranes containing aromaticcycloaliphatic polyamide skin layer on a reinforced polyethersulfone ultrafiltration membrane were prepared by in situ interfacial polymerization of 1,3-cyclohexanebis(methylamine) (CHMA) in water with trimesoyl ...
Journal of Membrane Science, 2013
Chemical modification was employed for tuning the molecular weight cut off (MWCO) values of poly(... more Chemical modification was employed for tuning the molecular weight cut off (MWCO) values of poly(acrylonitrile-co-methacrylic acid) hollow fibre ultrafiltration membranes by treating them with aqueous NaOH solutions of different concentration (0.25, 0.75, 1.25 and 1.75 M) separately for 1, 3, 6 or 9 h and then with 0.1 M HCl solution for 2 h at room temperature. This has resulted in the decrease of MWCO values of the fibres from the initial 92 kDa to the range of 9-75 kDa. The flux was decreased from 215 to 28-150 L/m 2 h at 1.5 kg/cm 2. NaOH-HCl treated fibres exhibited somewhat higher MWCO value and permeate flux than those of the fibres which were treated with NaOH only. Modified fibres exhibited lower fouling tendency for the ultrafiltration of aqueous solutions of polyethyleneoxide and bovine serum albumin, as indicated by their flux recovery ratio values of 91%-93%, when compared to the 53%-58% for virgin fibres. IR spectra of NaOH treated fibres showed a new peak at about 1580 cm À 1 due to the conversion of nitrile group to cyclic-CQN-naphthyridine structure. HCl treatment was resulted in the disappearance of the peak at 1580 cm À 1 and appearance of a new peak around 1695 cm À 1 due to the amide carbonyl group that was generated by the hydrolysis of naphthyridine structure. The fibres were characterized by scanning electron microscopy, contact angles and zeta potential measurements.
Desalination, 2008
Membranes with high permeation combined with high rejection rate and high fouling resistance are ... more Membranes with high permeation combined with high rejection rate and high fouling resistance are in high demand in market. The stability of membrane is necessary in aqueous applications for separation of biological products such as proteins. Polyethersulfone (PES) is hydrophobic material hence it fouls rapidly during aqueous biological and macromolecular solute separations. Membrane with hydrophilic characteristics have drawn considerable attention in practical use in recent years because of its better fouling resistance. This paper is an attempt to prepare hydrophilic PES membranes by blending polyethersulfone (PES) and polyacrylonitrile (PAN) in dimethylformamide (DMF) solvent in different proportions. Blend ultrafiltration membranes of PES and PAN were prepared on non-woven polyester fabric using motor driven prototype membrane casting machine according to phase inversion method. It has been observed that these membranes foul rapidly during ultrafiltration of macromolecular solutes. To improve fouling resistance membrane surfaces modified by treatment with aqueous alkali solutions of different concentration at room temperature. Unmodified and modified membranes were characterized using aqueous solution of inorganic solutes (NaCl & Na 2 SO 4) and organic solutes (polyethyleneglycol [PEG], dextran [DXT], poly (sodium 4-styrene sufonate) [PSSA]). Modified membrane had shown high flux recovery ratio compared to unmodified membranes, this improvement in the fouling resistance is due to hydrophilicity of membrane surface. Hydrophilicity was confirmed by advanced contact angle using DATA Physics direct contact angle tensiometer. Compatibility of polymer blends was confirmed by measuring glass transition temperature using differential scanning
Water reclamation from grey-water containing detergent and salinity ($2,000 ppm) was carried out ... more Water reclamation from grey-water containing detergent and salinity ($2,000 ppm) was carried out using indigenously developed brackish water TFC membrane module (4040 size) at 250 psi operating pressure. Reusable water with <300 ppm inorganic solutes and trace amounts of organic content of detergent origin was produced upon reverse osmosis (RO) treatment of grey-water. The RO module performance in terms of product flux was influenced by the detergent type present in the feed water. While the product flux was rather unchanged for the feed containing a commercial linear alkyl benzene-alfa olefin sulfonatesoda ash based detergent, a significant flux decline ($25%) was observed for the feed containing a commercial C 8 -C 24 primary/secondary ethoxylates based detergent. However, the membrane selectivity in terms of salt rejection was slightly higher for the feed with detergent than that of the detergent-free feed. This can be due to the surface-active agent of the detergent which alters the surface potential of the membrane. This is in agreement with the changes observed by atomic force microscopy (AFM) and the Zeta-potential measurements.
Journal of Membrane Science, 2008
Novel composite nanofiltration membranes containing aromaticcycloaliphatic polyamide skin layer ... more Novel composite nanofiltration membranes containing aromaticcycloaliphatic polyamide skin layer on a reinforced polyethersulfone ultrafiltration membrane were prepared by in situ interfacial polymerization of 1,3-cyclohexanebis(methylamine) (CHMA) in water with trimesoyl ...
Journal of Membrane Science, 2013
Chemical modification was employed for tuning the molecular weight cut off (MWCO) values of poly(... more Chemical modification was employed for tuning the molecular weight cut off (MWCO) values of poly(acrylonitrile-co-methacrylic acid) hollow fibre ultrafiltration membranes by treating them with aqueous NaOH solutions of different concentration (0.25, 0.75, 1.25 and 1.75 M) separately for 1, 3, 6 or 9 h and then with 0.1 M HCl solution for 2 h at room temperature. This has resulted in the decrease of MWCO values of the fibres from the initial 92 kDa to the range of 9-75 kDa. The flux was decreased from 215 to 28-150 L/m 2 h at 1.5 kg/cm 2. NaOH-HCl treated fibres exhibited somewhat higher MWCO value and permeate flux than those of the fibres which were treated with NaOH only. Modified fibres exhibited lower fouling tendency for the ultrafiltration of aqueous solutions of polyethyleneoxide and bovine serum albumin, as indicated by their flux recovery ratio values of 91%-93%, when compared to the 53%-58% for virgin fibres. IR spectra of NaOH treated fibres showed a new peak at about 1580 cm À 1 due to the conversion of nitrile group to cyclic-CQN-naphthyridine structure. HCl treatment was resulted in the disappearance of the peak at 1580 cm À 1 and appearance of a new peak around 1695 cm À 1 due to the amide carbonyl group that was generated by the hydrolysis of naphthyridine structure. The fibres were characterized by scanning electron microscopy, contact angles and zeta potential measurements.
Desalination, 2008
Membranes with high permeation combined with high rejection rate and high fouling resistance are ... more Membranes with high permeation combined with high rejection rate and high fouling resistance are in high demand in market. The stability of membrane is necessary in aqueous applications for separation of biological products such as proteins. Polyethersulfone (PES) is hydrophobic material hence it fouls rapidly during aqueous biological and macromolecular solute separations. Membrane with hydrophilic characteristics have drawn considerable attention in practical use in recent years because of its better fouling resistance. This paper is an attempt to prepare hydrophilic PES membranes by blending polyethersulfone (PES) and polyacrylonitrile (PAN) in dimethylformamide (DMF) solvent in different proportions. Blend ultrafiltration membranes of PES and PAN were prepared on non-woven polyester fabric using motor driven prototype membrane casting machine according to phase inversion method. It has been observed that these membranes foul rapidly during ultrafiltration of macromolecular solutes. To improve fouling resistance membrane surfaces modified by treatment with aqueous alkali solutions of different concentration at room temperature. Unmodified and modified membranes were characterized using aqueous solution of inorganic solutes (NaCl & Na 2 SO 4) and organic solutes (polyethyleneglycol [PEG], dextran [DXT], poly (sodium 4-styrene sufonate) [PSSA]). Modified membrane had shown high flux recovery ratio compared to unmodified membranes, this improvement in the fouling resistance is due to hydrophilicity of membrane surface. Hydrophilicity was confirmed by advanced contact angle using DATA Physics direct contact angle tensiometer. Compatibility of polymer blends was confirmed by measuring glass transition temperature using differential scanning
Water reclamation from grey-water containing detergent and salinity ($2,000 ppm) was carried out ... more Water reclamation from grey-water containing detergent and salinity ($2,000 ppm) was carried out using indigenously developed brackish water TFC membrane module (4040 size) at 250 psi operating pressure. Reusable water with <300 ppm inorganic solutes and trace amounts of organic content of detergent origin was produced upon reverse osmosis (RO) treatment of grey-water. The RO module performance in terms of product flux was influenced by the detergent type present in the feed water. While the product flux was rather unchanged for the feed containing a commercial linear alkyl benzene-alfa olefin sulfonatesoda ash based detergent, a significant flux decline ($25%) was observed for the feed containing a commercial C 8 -C 24 primary/secondary ethoxylates based detergent. However, the membrane selectivity in terms of salt rejection was slightly higher for the feed with detergent than that of the detergent-free feed. This can be due to the surface-active agent of the detergent which alters the surface potential of the membrane. This is in agreement with the changes observed by atomic force microscopy (AFM) and the Zeta-potential measurements.