Anoop Verma

An efficient TiO2 coated immobilized system for the degradation studies of herbicide isoproturon: Durability studies

The investigation presents the observations on the use of cement beads for the immobilization of TiO2 for the degradation of herbicide isoproturon. The immobilized system was effective in degrading and mineralizing the herbicide for continuous thirty cycles without losing its durability. Catalyst was characterized by SEM-EDAX for checking the durability of the catalyst. The degradation rate followed first order kinetics as measured by change in absorption intensity in UV range as well as HPLC analysis. Two rounds of TiO2 coating on inert cement beads with average diameter 1.5cm at UV Intensity 25Wm(-2) calcined at 400°C were the optimized conditions for the degradation of herbicide isoproturon. More than 90% TOC and COD reduction along with ammonium ions generation (80%) confirmed the mineralization of isoproturon. Fixed bed baffled reactor studies under solar irradiations using the TiO2 immobilized beads confirmed 85% degradation after 6h. LC-MS studies confirmed the intermediates formation and their subsequent degradation using immobilized system.

Photocatalytic, Sonolytic and Sonophotocatalytic Degradation of 4-Chloro-2-Nitro Phenol

Abstract The photocatalytic, sonolytic and sonophotocatalytic degradation of 4-chloro-2-nitrophenol (4C2NP) using heterogeneous (TiO2) was investigated in this study. Experiments were performed in slurry mode with artificial UV 125 watt medium pressure mercury lamp coupled with ultrasound (100 W, 33+3 KHz) for sonication of the slurry. The degradation of compound was studied in terms of first order kinetics. The catalyst concentration was optimized at 1.5 gL-1, pH at 7 and oxidant concentration at 1.5 gL-1. The results obtained were quite appreciable as 80% degradation was obtained for photocatalytic treatment in 120 minutes whereas, ultrasound imparting synergistic effect as degradation achieved 96% increase in 90 minutes during sonophotocatalysis. The degradation follows the trend sonophotocatalysis > photocatalysis > sonocatalytic > sonolysis. The results of sonophotocatalytic degradation of pharmaceutical compound showed that it could be used as efficient and environmentally friendly technique for the complete degradation of recalcitrant organic pollutants which will increase the chances for the reuse of wastewater.

Photocatalytic treatment of pharmaceutical industry wastewater over TiO2 using immersion well reactor: synergistic effect coupling with ultrasound

AbstractThe sonophotocatalytic degradation of pharmaceutical industry wastewater was studied with a TiO2 slurry mode process with UV 125 W medium-pressure mercury lamp coupled with ultrasound (100 W, 33 ± 3 kHz). The degradation of wastewater was investigated in terms of reduction in COD that confirmed the apparent first- order degradation kinetics. The rate constant was greatly affected by catalyst dose, variation in pH, and concentration of oxidant (H2O2).The catalyst concentration was optimized at 1.0 g L−1, pH at 4, and the oxidant concentration at 0.075 g L−1. The first-order rate constants obtained from coupled sonophotocatalysis were two-folds than those obtained from photocatalysis and approximately ten-folds than sonolysis. The COD reduction follows the trend, sonophotocatalysis > photocatalysis > sonocatalytic > sonolysis. The study demonstrates better efficiency of coupled sonophotocatalysis over independent treatment processes.

Heterogeneous solar photo-fenton degradation of reactive black 5 using foundry sand and fly ash: value addition to waste

AbstractThis work evaluates the scope of alternative sources of iron i.e. Foundry Sand (FS), Fly Ash (FA) and mixture of FS and FA in heterogeneous photo-Fenton process for the degradation and decolourization of the dye Reactive Black5 (RB5). SEM-EDS characterization of FS and FA confirmed the presence of iron and aluminium which are required for photo-Fenton. In case of FS as an iron source, results confirmed the degradation and decolourization efficiency of 90% in 70 min and 45 min respectively when the reaction parameters were H2O2 = 2.2 mM, FS dose = 0.5 g, pH 3. With FA 90% degradation was achieved within 30 min and 93% decolourization rate within 15 min. When a mixture of FS (0.1 gm) and FA (0.05 gm) is used as source of iron 99% degradation and decolourization of the dye was achieved under the reaction conditions where H2O2 = 2.2 mM, FA:FS = 1:2, pH 3.

Sequential photo-Fenton and sono-photo-Fenton degradation studies of Reactive Black 5 (RB5)

AbstractSequential treatment studies have been done using photo-Fenton and sono-photo-Fenton, and compared with individual processes to analyze possible favorable effects of combined systems for the degradation of Reactive Black 5 (RB5). The coupled system enhances the degradation as compared to the ultrasound or UV–light irradiation processes along with the reduction in treatment time. Batch runs were carried out to investigate the process operational conditions: pH, H2O2 dosage, Fe2+ dosage, and RB5 concentration; to obtain the results at best possible operating conditions render advanced oxidation processe (AOP) competitive with other processes; and to ensure the rapid and complete transformation of the toxic organic compounds to benign chemicals. Degradation observed was 69% under Fenton and 93% under photo-Fenton with experimentally optimized conditions i.e. pH 4, Fe2+ concentration 0.050 gL−1 and H2O2 0.150 gL−1 after 20 min. Sono-photo-Fenton treatment enhances the degradation up to 98% with experi...

Assessment of solar photocatalytic degradation and mineralization of amoxicillin trihydrate (AMT) using slurry and fixed-bed batch reactor: efficacy of parabolic trough collector

Heterogeneous photocatalytic mineralization of amoxicillin trihydrate (AMT) using TiO2 in suspended and supported form has been investigated in the present study. Cement beads and alginate balls were used for the immobilization of TiO2 for the degradation of AMT. The dip coating method was used for catalyst immobilization on the cement beads, whereas the catalyst was physically entrapped in alginate gel. 87%, 69% and 51% degradation was observed under shallow pond slurry reactor, coated cemented beads and immobilized sodium alginate balls, respectively, at optimized conditions. XRD and solid spectra analysis of TiO2 confirmed that no deformities occurred in the structure of catalyst after use. Reduction in COD and TOC along with the generation of ammonium ions further indicates the mineralization of AMT. Experiments conducted on a parabolic trough collector (PTC) with TiO2 immobilized cement beads at a flow rate of 1.0 L min−1 in the presence of oxidant (0.12 g L−1) yielded 92% degradation within 4 h of irradiation. The structure of TiO2 was found to be intact after the fifth recycle.

Catalyst-coated cement beads for the degradation and mineralization of fungicide carbendazim using laboratory and pilot-scale reactor: catalyst stability analysis

ABSTRACT The fixed-bed photocatalytic degradation of fungicide carbendazim using catalyst-coated spherical cement beads has been investigated. Thirty beads with optimum size 13 mm along with 0.3 gL−1 H2O2 with an initial concentration of carbendazim of 10 mgL−1 were the optimized conditions for better degradation. The reduction in COD and total organic carbon along with the generation of nitrite and nitrate ions under the optimized conditions confirms the complete mineralization of compound. The suggested degradation pathway for carbendazim has also been proposed as intermediates formed during photodegradation were analyzed through gas chromatography–mass spectrometry. The coated cement beads were found to be durable even after 30 cycles as confirmed by scanning electron microscopy and energy dispersive spectroscopy analysis. Scale-up trails have also been carried out in a solar-baffled fixed-bed reactor for the degradation of pollutant to seek the commercial viability of the technique. GRAPHICAL ABSTRACT

Stability and durability studies of TiO2 coated immobilized system for the degradation of imidacloprid

The present article demonstrates the use of supported TiO2 for studying the degradation of an insecticide, imidacloprid (IMI), along with durability studies of the catalyst. Operating conditions for the best degradation were optimized in suspension mode by varying the dose of TiO2, H2O2, pH and area/volume ratio of the batch reactor. With all conditions optimized, approximately 95% degradation of IMI was achieved after 3 h of photocatalytic treatment. For fixed-bed studies, TiO2 coated spherical cement beads were used for the degradation of IMI. Studies on the number of catalyst coatings, calcination temperature and catalyst durability were undertaken for the degradation. Spherical beads having a diameter of around 2.0 cm with two coatings of catalyst were efficient enough for 89% degradation of IMI after 6 h of treatment. The stability and efficacy of the supported catalyst were assessed by recycling the beads more than 30 times. The catalyst was characterized by SEM/EDS, XRD and DRS analysis. The durability of the catalyst was further confirmed by using catalyst coated beads that had previously been used for 100 cycles. The mineralization of IMI was validated by reduction in COD along with chloride ion (Cl−1) generation. A tentative degradation pathway for IMI has been proposed by carefully identifying the intermediates using GC-MS analysis.

N, Ag co-doped TiO2 mediated modified in-situ dual process (modified photocatalysis and photo-Fenton) in fixed-mode for the degradation of Cephalexin under solar irradiations

Novel FeNAgTiO2 composite beads possessing unusual characteristics of modified in-situ dual process (modified photocatalysis and photo-Fenton) resulted in reduction in treatment time of Cephalexin (CEX). These composite beads were prepared using NAgTiO2 and waste foundry sand (FS) and fly-ash (FA) as alternative source of iron. The modified TiO2 was characterized through SEM/EDS, DRS, XRD, TGA, FTIR, XPS and Raman spectroscopy to affirm the distribution of Ag and N on TiO2 surface. The modified in-situ dual process using FeNAgTiO2 composite beads yielded 77% degradation of CEX after 60 min of solar irradiations with overall synergy of 24% over individual processes. FeNAgTiO2 composite beads were characterized through SEM/EDS, XRD and DRS to confirm the presence of Fe along with Ag, N and TiO2 on the surface of beads. These composite beads were stable and active even after 15 recycles. The mineralization of CEX was validated through reduction in COD and TOC along with generation of anions while intermediates were identified through GC-MS analysis.