Nageswara Rao Neti

Synthesis of C-Doped TiO2 Nanoparticles by Novel Sol-Gel Polycondensation of Resorcinol with Formaldehyde for Visible-Light Photocatalysis

Nanosized C-doped TiO 2 was prepared by a new method based on resorcinol-formaldehyde (RF) gel formation in situ during hydrolysis of Ti precursor (TTIP, titanium tetraisopropoxide). XRD, DRS, EDX, SEM and HRTEM results confirmed that the carbon in the sample existed as free carbon (C–C), carbonate carbon (–CO 3 ) and doped into lattice of TiO 2 (Ti–C), resulting in red shift of optical adsorption edge and band gap narrowing. The photo activity of the C-doped TiO 2 , tested on 2-chlorophenol, revealed that it was more active under visible light (k vis = 3.50 × 10 −3 min −1 ).

Advanced treatment of refractory sebacic acid wastewater

AbstractAdvanced treatment of refractory sebacic acid (SA) present in wastewater discharges from SA manufacturing industry (SAWW) is reported. Ion exchange (IE), electrochemical oxidation (EO), EO coupled with electrocoagulation (EO–EC), wet air oxidation (WAO), and catalytic wet air oxidation (CWAO) experiments were conducted. It is found that SA can be efficiently removed from aqueous solutions using a strong base anion-exchange resin (Amberlite IR 400), which showed a breakthrough capacity of 49.0 mg SA/mL resin (0.485 meq/mL). However, presence of inorganic anions (, , Cl–, and ) is detrimental. Regeneration and reuse of spent resin, the effect of inorganic anions and morphology (SEM) of spent resin were also investigated. In addition, batch EO experiments conducted using Ti/RuO2-Pt anode and stainless steel (SS) cathode showed poor mineralization efficiency (8.4%). Pd2+-catalyzed WAO experiments performed in a high pressure reactor (473 K, 0.689 MPa, 2 h) provided more efficient mineralization of SA ...

Preparation, Characterization and Photocatalytic Application of Carbonate Modified Titania

Carbonate is a common pollutant in water and wastewater. A study to understand its influence on the photodegradation rates is necessary especially when TiO2/UV technique is emerging as an advanced technology for pollution abatement. In the present investigation, we report surface modification of titanium dioxide using carbonate ions, characterization of carbonate modified titanium dioxide (CMT) and photocatalytic application of carbonate modified TiO2. Titanium dioxide from two different sources namely BDH, Mumbai and Degussa AG, Germany was used as photocatalyst. The CMT catalysts were characterized using potentiometry, FT-IR and XPS. Approximately, 18.9 mg CO3/g CMT(BDH) and 8.13 mg CO3/g CMT(Degussa) was found loaded as determined by potentiometry. The C 1s and O 1s binding energies observed at 289.2 and 531.3 eV, respectively were attributed to surface carbonate species. The adsorption and photodegradation of Acid Blue I dye examined using neat TiO2 as well as CMT catalysts revealed that carbonate inhibits catalytic activity for color and Chemical Oxygen Demand (COD) removal. The photo degradation rate constant (k, s-1) decreases gradually with increasing concentration of carbonate. Thus, in the absence of carbonate kdye is 5.45 × 10-4 s-1 (R2 = 0.97) and kCOD is 3.50 × 10-5 s-1 (R2 = 0.97). At 100 mg/L CO32-, kdye is 0.16 × 10-4 s-1 (R2 = 0.96) and kCOD is 2.66 × 10-5 s-1 (R2 = 0.98). In addition, the carbonate spiking studies revealed the onset of inhibition soon after the addition of carbonate into reacting suspensions of TiO2. The results suggest that carbonate inhibits catalytic activity through formation of strong surface complex under suitable pH by displacing OH2+ and OH groups from TiO2 surface. This results not only in fewer (OH)surface groups available for h+ trapping for oxidation into OH radicals but also in non-availability of adsorption sites for the dye molecules. A pretreatment to remove carbonate from (waste) water appears necessary prior to application of TiO2/UV technique

Photocatalysts and Photoreactors for Treatment of Industrial Effluents

Development of photocatalysts and photoreactors for treatment of industrial effluents is considered important to harness solar energy for environmental clean up. The photocatalytic method of decolorization of textile dyes utilizes UV component of sunlight (3-5%) and the only solid phase (TiO2 catalyst) can be recycled on a technical scale. Moreover, the method does not produce any sludge unlike adsorption and coagulation methods. These attributes of the photocatalytic method are attractive for possible application in industry. Our group is presently working on pilot scale photoreactors and exploring feasibility of industrial application of this technique. We have developed a few TiO2 based photocatalysts (P-25 TiO2, ZnO, TiO2 (bulk) and rare earth metal (In2O3, Nd2O3, Yb2O3 and Sm2O3) doped TiO2), photo catalyst bearing supports (e.g., acrylic sheet) and photoreactors (annular immersion well type, falling film type and shallow slurry photoreactors) for use with UV & sunlight. We have carried out a few tests with Solar Slurry Photoreactor (SSPR) in field using actual textile wastewater with encouraging results. The SSPR developed under this study was capable of decolorizing textile wastewater under specified conditions approximately with a treatment rate of 9.0 Lh-1. The reactor area exposed to sunlight was approximately 1 m2. Thus, a reactor having 18-20 m2 exposed area would treat about 1.0 m3 textile wastewater at a rate approximately equal to180 Lh-1. The present data suggest that it may be possible to apply this technique initially for the color treatment of textile wastewater from small dyeing operations. However, the details of techno-economic feasibility need to be assessed beforehand. The proposed book chapter would present details of all the above-mentioned efforts. It would be targeted to bring out inadequacies associated with the photocatalytic technology for wastewater treatment.