Hafiz Zahid Shafi
KFUPM, Mechanical Enggineering, Faculty Member
- Enthusiastic researcheredit
ABSTRACT GeC thin films have been prepared by reactive pulsed laser ablation technique. Methane pressure (P(CH4)) was varied from 0 to 75 milli torrs (mT). Optical analysis of all the samples was performed by spectroscopic ellipsometry... more
ABSTRACT GeC thin films have been prepared by reactive pulsed laser ablation technique. Methane pressure (P(CH4)) was varied from 0 to 75 milli torrs (mT). Optical analysis of all the samples was performed by spectroscopic ellipsometry (SE). The optical constants i.e. refractive index (n), extinction coefficient (k), absorption coefficient (alpha) and thickness of deposited film(s) were obtained by modeling and simulations of ellipsometric data. It was found that deposition parameter (change in pressure of methane) has a profound effect on the properties of the deposited films. To support our results of optical analysis, other important diagnostic techniques like atomic force microscopy (AFM), Fourier Transform Infrared Spectroscopy (FTIR) etc. were employed.
Research Interests:
Research Interests:
• Surface modification of commercial RO desalination membranes • p(4VP-co-EGDA) co-polymerization via initiated chemical vapor deposition • Functionalization of the co-polymer to carboxybetaine zwitterion surface moieties • Significant... more
• Surface modification of commercial RO desalination membranes • p(4VP-co-EGDA) co-polymerization via initiated chemical vapor deposition • Functionalization of the co-polymer to carboxybetaine zwitterion surface moieties • Significant reduction of bacterial cell attachment on modified membrane surface • Perm selectivity under cross flow conditions comparable to virgin membranes a b s t r a c t Copolymer films of poly(4-vinylpyridine-co-ethylene glycol diacrylate) (p(4-VP-co-EGDA)) were synthesized and first deposited on various substrates via initiated chemical vapor deposition (iCVD). As-deposited copolymer films were converted to surface zwitterionic structures containing poly(carboxybetaine acrylic acetate) (pCBAA) units by a quaternization reaction with 3-bromopropionic acid (3-BPA). Conversion to a zwitterionic structure was confirmed by FTIR and high-resolution XPS N1s scans. Biopolymer adsorption of the deposited copolymer coatings was investigated by quartz crystal microbalance with dissipation (QCM-D) using a model foulant‐ bovin serum albumin (BSA). The optimized copolymer films were then deposited onto commercial RO membranes and with subsequent zwitterionicalization. Inertness to bacterial adhesion of the modified membranes was investigated by counting the number of Escherichia coli and Pseudomonas aeruginosa cells attached on the membrane surface under static conditions. Bacterial adhesion studies revealed an almost 98% reduction in microorganism attachment onto the surface of modified membranes compared to bare membranes, which clearly demonstrates the effectiveness and superior performance of the zwitterionic coating against bacterial adhesion. The salt rejection performance of the modified membranes resulted in improved salt rejection (98%); however, permeate flux was slightly compromised compared to virgin membranes. AFM analysis demonstrated that modified membranes showed lower RMS roughness compared to virgin membranes.