in partial fulfillment of the requirements for the degree of

Effect of superficial gas velocity on gas holdup at different initial volumes of the liquid. Variation of the pseudo-first-order rate constant  kapp with the pH of the medium for the ozone feed rate of 0.44 mg s and initial DCF concentration of 50 mg dm.

Figure 7.1. Chromatogram of raw pharmaceutical industrial effluent. 201 Figure 7.2

INTRODUCTION AND LITERATURE REVIEW

Although the amounts of drugs were in the range of µg dm, the chronic effects of these compounds are due to their long duration. Qualitative analysis of sewage plays a key role in the degradation process and its efficiency.

Figure 1.1. Revenue of the pharmaceutical industries in last 20 years around the world [1–3].

MATERIALS AND METHODS

Experimental setup

An ozonation system used to degrade pharmaceutical wastewater consists of an oxygen concentrator, an ozone generator connected to a nebulizer, a glass reactor, and an ozone destructor to reduce excess ozone. To supply ozone to the reactor vessel. In this method, the applied voltage created nascent oxygen, which combined with the oxygen molecule to create ozone.

A rotameter (Manufacturer: Instrumentation Engineers Pvt. Ltd., Model: 1114C, Country: India) was used to measure the flow rate of the ozone-oxygen mixture emerging from the ozone generator. The pore size of the nebulizer (Manufacturer: Oz-Air, Model: S4, Country: India) used in this study was 40 µm. The pH of the samples was monitored using an inline pH meter (Brand: Equiptronics, Model: EQ 610, Country: India).

The surface morphology and pore structure of the used sparger were analyzed by FESEM (make: Jeol, model: JSM-7610F, country: Japan).

Figure 2.1. Schematic of the experimental setup for ozonation process.

Chemical and reagents used

Analytical methods

Details of mobile phase composition and gradient method are given in Table 2.3. Raw wastewater properties were measured with a photometer (Manufacturer: Palintest, Model: . 7100, Country: UK). A reagent containing silver nitrate was then added and the chloride present in the sample reacted with it to form a cloudy dispersion of silver chloride.

The COD reagents were carefully added to the COD vials and dissolved for 2 h in the COD solvent (Make: Velp Scientifica, Model: ECO 25, Country: India) at 423 K. Then, the dissolved samples were kept at room temperature for to get cold. , and COD was measured. The instrument displays the carbon content present in the sample as TOC content in mg dm.

The concentration of dissolved ozone in the reactor was quantified with a photometer using the ozone-specific reagent DPD (diethyl-p-phenylenediamine).

Table 2.2. Operating conditions for HPLC analysis

OZONE MICROBUBBLE-AIDED

INTENSIFICATION OF DEGRADTION OF NAPROXEN IN A PLANT PROTOTYPE

KINETICS AND MASS TRASNFER

Introduction

NPX is a nonsteroidal anti-inflammatory drug (NSAID) that works by reducing hormones in the body that cause inflammation and pain. NPX is a pain reliever used to treat conditions such as arthritis, tendinitis, ankylosing spondylitis, bursitis, and menstrual cramps. Traces of NPX have been found in water bodies due to extensive use of it as a pain reliever.

The ineffectiveness of conventional treatment methods and the toxicity of metabolites generated during oxidation have been reported in previous studies. This work focuses on the complete removal of NPX under different operating variables and the intermediates generated during the process.

Results and Discussion

For the determination of the ozone volume mass transfer coefficient, two phenomena are important, i.e., the mass transfer of gaseous ozone to the aqueous phase and the rate of self-decomposition of ozone adsorbed in solution. The solubility of ozone in water was several times higher than that of oxygen (i.e., the solubility of the mole fraction of oxygen in water is 2.3×105 and the same for ozone is 9.1×105 in 298 K and atmospheric pressure). The concentration of ozone in the aqueous phase can be described by Henry's law: p = Hc.

The concentration of ozone in water increases with time and reaches equilibrium after a certain time. The diffusion of ozone in the gas phase is much higher than that in water. With the decomposition of ozone and the mass transfer rate of ozone, the mass balance equation of ozone can be written as.

For the same amount of ozone input and residence time, the degradation in the acidic medium was relatively slower than in the alkaline medium.

Figure 3.1. A typical example of image analysis for measuring the size of the microbubbles

O NPX

The values ​​of the reaction rate constant for different pH and ozone feed rate are summarized in Table 3.5. Rate constant values ​​for the O3/H2O2 system were always higher than those for O3 alone (see Figure 3.13) due to the involvement of the hydroxyl radicals. It may be due to the insufficient amount of hydroxyl radicals in the alkaline medium for ozone alone.

The full scan ESI mass spectrum of the NPX metabolites (negative ions) was performed on the samples collected from the reactor. In the first step, NPX was attacked by the hydroxyl radical and an unstable intermediate was formed. Intermediate B further forms 1-(6-methoxynaphthalen-2-yl) ethyl hydroperoxide (m/z = 216.6) as a result of the combination of the oxygen radicals.

Degradation of NPX was investigated using ozone microbubbles in the presence and absence of H2O2.

Figure 3.11. Plot of  

OZONATION OF DICLOFENAC IN A LABORATORY-SCALE BUBBLE COLUMN

INTERMEDIATES, MECHANISM, AND MASS TRANSFER STUDIES

Introduction

DCF is one of the commonly used analgesic, antiarthritic and anti-inflammatory nonsteroidal drugs (NSAID). Although it is a proven fact that DCF can be removed by natural photolysis, it is still one of the most commonly found drugs in water bodies such as groundwater [137,138] and surface water in concentrations up to 1.2 µg ds. The potential of AOPs for drug degradation from wastewater has been well established in previous studies.

However, only a limited amount of studies are available for the intermediates and the degradation mechanism. The effects of system pH, ozone supply rate and initial concentration of the substrate were studied in detail. A kinetic model for the ozonation of DCF was developed and the kinetic parameters of the model were determined from the experimental data.

Mass transfer of ozone in the aqueous phase was analyzed and the mass transfer parameters were calculated.

Results and Discussion

The increase in the rate of degradation of DCF with the pH of the medium indicates in situ generation of the hydroxyl radicals. Non-selectivity and higher oxidizing power of the hydroxyl radicals make them a better oxidizing agent than molecular ozone for the oxidation of DCF. Involvement of the hydroxyl radical in the oxidation of DCF was also confirmed by adding a catalyst and a scavenger for the hydroxyl radical (see Section 4.2.2).

Change of the pseudo-first-order rate constant  kapp with medium pH for an ozone feed rate of 0.44 mg s and an initial DCF concentration of 50 mg. Direct ozonation of the parent compound resulted in the production of less degradable intermediates that can be partially scavenged by hydroxyl radicals. The dependence of the pseudo-first-order rate constant on the operating parameters was also studied.

Due to the unstable nature of ozone and the limitations encountered during the measurement of the concentration of hydroxyl radicals in the reaction medium, the ozone supply was considered as an independent variable.

Figure 4.2. Variation of the pseudo-first-order rate constant   k app with the pH of the medium for the ozone supply rate of 0.44 mg s  and initial DCF concentration of 50 mg

Conclusions

It can be concluded that the substances present in the waste water competed with DCF to take up the oxidant present in the solution. Therefore, the availability of ozone and hydroxyl radicals for oxidizing DCF decreased and a reduced removal rate was observed. The presence of other contaminants can be expected to inhibit the degradation process, so that the removal efficiency achieved in the case of ultrapure water cannot be achieved in real wastewater.

88% of total chlorine and 72% of total nitrogen were released during the degradation process. The mineralization of DCF by ozone mainly consisted of three steps, i.e., oxidant attack, CN bond cleavage, and ring opening. The major intermediates detected in HR-LCMS were dichloro aniline, 5-hydroxy DCF, DCF-2 5-iminoquinone, 2-chloro benzoate, phenylacetic acid derivatives, and carboxylic acids (eg, acetic, formic, and oxalic acids).

A Pre-exponential factor in the Arrhenius equation (s1) A Coefficient in the correlation given by equation (4.6) (s1) a Coefficient in the correlation given by equation (4.6) (-) b Coefficient in the correlation given by equation (4.6).

One of the important factors affecting the degradation of RNT is the initial pH of the wastewater. A higher dose of ozone in the reaction system increased the rate of hydroxyl radical formation. During RNA degradation, reactions with hydroxyl radicals take place, whereby the latter are consumed.

The involvement of the hydroxyl radical and its effect on the degradation of RNT is shown in Figure 5.4. The availability of ozone in the aqueous solution primarily controls the rate of degradation of RNT. In the second pathway, the degradation of RNT started with the binding of the oxygen atom to the nitrogen atom (i.e., M1, m/z 330).

The proposed reaction pathway for the ozonation of RNT is shown schematically in Figure 5.11.

Figure 5.1. Degradation of RNT by ozone at pH 4 – 9 and [RNT] 0 = 50 mg dm  for the ozone supply rate (a) 0.44 mg s  , (b) 0.48 mg s  , and (c) 0.50 mg s 

TREATMENT OF A REAL PHARMACEUTICAL INDUSTRIAL EFFLUENT BY A HYBRID

ADSORPTION BY ACTIVATED CHAR

Introduction

Most pharmaceutical industries are located in the Indian cities of Ahmedabad, Bangalore, Hyderabad and Mumbai. Recent studies have found traces of pharmaceuticals in the lakes, rivers and wells in Hyderabad [263,283]. Although drug amounts were within the range of µg dm, the chronic effects of these compounds are caused by their prolonged exposure [18,19].

Most of the AOPs involve the formation of the hydroxyl radical as the primary oxidant. However, the commercial application of the AOPs is still scarce due to their high cost. The present study covers the complexities encountered in the treatment of real wastewater viz. the presence of matrices and interference from other organic compounds.

The presence of drugs against cancer, antipsychotics, antidepressants and antibiotics was confirmed in the effluent.

Results and discussion

As the pH rises, the high rate of ozone depletion leads to the formation of hydroxyl radicals, see equation. As the organic compounds present in the aqueous medium are broken down, the concentration of carbonates and bicarbonates increases. Carbonates and bicarbonates not only hinder the production of the accelerators for the breakdown of O3, such as O2.

After 100 minutes of reaction, the increase in the concentration of these scavengers significantly slows down the reaction. It is therefore concluded that the alkaline medium promotes mineralization, but that the ozone concentration or its exposure over a longer period of time does not appreciably accelerate mineralization. The reaction rate equation can be written in terms of COD and ozone concentrations in the solution as follows:

Figure 6.1. Chromatogram of the industrial wastewater.

COD    COD

COD  0

Conclusion