Deposition of transparent, hydrophobic polydimethylsiloxane - nanocrystalline TiO2 hybrid films on glass substrate

Transparent, hydrophobic hybrid films were deposited on glass substrate from solution containing hydroxyl-terminatedpolydimethylsiloxane (PDMS) and TiO2 sol by using a dip coating method. The effects of the film heat-treatment temperatureand PDMS/TiO2 component on surface properties of the hybrid films were investigated by water drop contact angle measurement,and by atomic force microscopy (AFM) and scanning electron microscope (SEM) analyses. Surface morphology of the hybrid film changed from smooth surface containing tiny spikes to rougher surface containing large protrusions during heattreatmenttemperatures of 60 - 300°C and became smooth surface containing very fine spikes at 500°C, corresponding to a change hydrophobicity behavior from contact angle measurement. The suitable condition for preparation of hydrophobic coating from this current recipe was at the PDMS/TiO2 volume ratio of 1.00 - 2.33 and heat-treatment temperature of 60°C. All the films were transparent regardless of post heat-treatment temperature. However, the films containing higher content of PDMS were slightly more transparent

Dissolution Performance of Carbon/Hydroxyapatite Nanocomposite Prepared from Fish Scales

The utilization of waste as raw materials in the production of functional materials is a growing area of interest to promote global sustainable growth. This work studied the microstructure, chemical properties, and phosphorus (P) dissolution efficiency of carbon/hydroxyapatite (HAP) nanocomposites derived from fish scale wastes, namely FSBCs. Tilapia scales were pyrolyzed at different temperatures (450–600 °C) and the dissolution performance of the biochars in acidic media was evaluated. The pyrolysis of fish scales yielded biochars which are carbon/HAP nanocomposites of which the characteristics, including the specific surface area, carbon content, degree of crystallinity of HAP, and the degree of CO32− substitution in HAP crystals, were dependent on the pyrolysis temperature and had an influence on the dissolution efficiency. P dissolution experiments suggested that the specific surface area and the presence of carbon in the composite played an important role during the dissolution process. The presence of the organic residues on the carbon could potentially block the calcium sites on HAP from citric acid and lower the dissolution efficiency. The ratio of CO32−/PO43− substitution in HAP also affected the dissolubility of FSBCs. The manipulation of their surface area and the CO32−/PO43− ratio of these materials would allow us to increase its solubility, which could benefit a prospective application such as P fertilizer production

Enhancement of Air Filter with TiO2 Photocatalysis for Mycobacterium Tuberculosis Removal

HEPA filter is normally recommended for removal of Mycobacterium tuberculosis from the airstream. Due to its high cost, a cheaper air-filter substitution is proposed in this study. Low grade and high grade glass fiber air filters were coated with 5 % TiO2 using polyethylene glycol (PEG), Silane (Si-69), or DURAMAX (D-3005) as a binder. The coated filter was placed in a test duct and irradiated with UVA at intensity of 4.85 ± 0.41 mW/cm2 to investigate photocatalysis for M. tuberculosis. The effects of dark and light conditions as well as initial exposure to UVA on bacterial removal were studied. Silver-doped and iron-doped TiO2 at different concentrations were also tested using face velocities of 0.1 and 1 m/s and humidity levels of 50 ± 10 % and 70 ± 10 % RH. The most appropriate binder for coating TiO2 onto filters was 3 % D3005. With 0.1 % metal-doping, 100 % removals were found. Dark/light conditions affected the hydrophobic/hydrophilic properties of TiO2-coated filters and the removal efficiencies. The removal rate could be increased by extending the warm up period of the lamps. When face velocity increased, the removal efficiency dropped in both filters. Similarly, high humidity adversely affected the removal efficiency, particularly with the coated high grade air filter

Solar photocatalytic degradation of carbendazim in water using TiO2 particle- and sol-gel dip-coating filters

Carbendazim degradation with TiO2 photocatalysis under sunlight irradiation using particle- and sol-gel coating filters was studied. For particle coating, an appropriate concentration of Degussa P25, namely 0.3, 0.5, and 1% w/v, and binder types, namely Duramax B1000, PEG1000, PEG2000, PEG4000, and PEG6000 were investigated. It was found that 0.5% w/v of P25 and 1 wt% of PEG6000 yielded the highest efficiency of 89–91% from triplicate runs. The best kinetic rate constant was 0.048 min−1. For sol-gel coating, different anatase to rutile (A/R) ratio were compared for efficiency. The synergistic effect from photocatalysis and sorption due to the honeycomb-like coating surface was observed. The efficiency of 98–99.5% in 10 min were obtained from PEG4000-6000. Zeta potential analysis revealed that the TiO2 from both coatings and carbendazim had negative charge, which was the same as that of the TiO2, then the sorption was not due to the opposite charge attraction

Dissolution Performance of Carbon/Hydroxyapatite Nanocomposite Prepared from Fish Scales

The utilization of waste as raw materials in the production of functional materials is a growing area of interest to promote global sustainable growth. This work studied the microstructure, chemical properties, and phosphorus (P) dissolution efficiency of carbon/hydroxyapatite (HAP) nanocomposites derived from fish scale wastes, namely FSBCs. Tilapia scales were pyrolyzed at different temperatures (450–600 °C) and the dissolution performance of the biochars in acidic media was evaluated. The pyrolysis of fish scales yielded biochars which are carbon/HAP nanocomposites of which the characteristics, including the specific surface area, carbon content, degree of crystallinity of HAP, and the degree of CO32− substitution in HAP crystals, were dependent on the pyrolysis temperature and had an influence on the dissolution efficiency. P dissolution experiments suggested that the specific surface area and the presence of carbon in the composite played an important role during the dissolution process. The presence of the organic residues on the carbon could potentially block the calcium sites on HAP from citric acid and lower the dissolution efficiency. The ratio of CO32−/PO43− substitution in HAP also affected the dissolubility of FSBCs. The manipulation of their surface area and the CO32−/PO43− ratio of these materials would allow us to increase its solubility, which could benefit a prospective application such as P fertilizer production

Performance of photocatalytic lamps on reduction of culturable airborne microorganism concentration

Reduction of viable airborne Staphylococcus epidermidis and Aspergillus niger spore concentrations using two types of photocatalytic fluorescent lamps under controlled environmental conditions (25 vs. 35 degrees C and 55 vs. 75% relative humidity) were investigated. Visible white-light and UVA black light were in-house spray-coated with TiO(2) and then compared with a commercially coated visible white-light for microbial concentration reduction. The white-light photocatalytic lamps reduced the concentration of culturable S. epidermidis up to 92% independent of temperature or humidity change, while the black light photocatalytic lamps completely inactivated the culturable bacteria at 25 degrees C, 55% relative humidity. Humidity seemed to alleviate UVA damage since better bacteria survival was found. For A. niger spores, rising humidity or temperature could lower their concentration or drop their culturabilities so that a difference between the natural decay and photocatalytic disinfection could not be distinguished. Reductions of total bacteria and total fungi concentrations using these lamps were also examined under uncontrolled environmental conditions in an office and a waste-storage room. It was found that photocatalytic lamps could reduce total culturable bacteria concentration from 9 to 97% and total culturable fungi concentration from 3 to 95% within irradiation time of 30-480 min, respectively. Insignificant difference in concentration reduction among these photocatalytic lamps was pronounced

Study of optimization condition for spin coating of the photoresist film on rectangular substrate by Taguchi design of an experiment

There are four parameters concerning the spin coating of a positive photoresist film. This paper focuses on spin coating of the positive photoresist Clariantz AZ-P4620 on a 2x7 cm rectangular substrate. By ways of Taguchi L16 (44) method, the number of experiments can be reduced from 256 to 16. By analyzing the main impact plot of the signal to noise ratio, it is found that the most suitable values of the four parameters giving the desired thickness and uniformity is a photoresist dispense time of 13 seconds, then spin at a speed of 700 rpm for 5 seconds, and then accelerate at 2,000 rpm per seconds to 4,000 rpm. The speed is maintained at 4,000 rpm for 60 seconds with an exhaust pressure of 300 Pa. The substrate is later baked at 100 oCfor 90 seconds. The calculated thickness of the final film is 48,107.70±1,096 Angstroms. The analysis of the deviation showsthat no parameter has a significant on the thickness and uniformity of the final photoresist film with a confidence level of 95%. This DOE can be used in many applications in the micro and nano fabrication industry