Oualid Hamdaoui

This research aims at optimizing the effects of processing conditions, salts, natural organic materials, and water matrices quality on the effectiveness of the Fe(II)/K2S2O8(KPS)/hydroxylamine process in the degradation of pararosaniline, a toxic and carcinogenic dye. Assisting the Fe(II)/KPS treatment with protonated hydroxylamine (H3NOH+) increas...

A comprehensive numerical investigation was conducted to analyze the effect of ultrasound frequency (213-1000 kHz), ultrasonic intensity (0.7-1.5 W/cm²) and medium temperature (293.15-333.15 K) on the production of hydrogen from methanol decomposition inside acoustic bubbles (methanol sono-conversion). The adopted model was firstly compared with so...

In the last decades, great interest has been focused on developing innovative, efficient and eco-friendly methods for the reduction of carbon dioxide (CO2). The use of ultrasound (sonochemistry) has appeared as one these techniques, thanks to its operational simplicity (working at ambient conditions), safety and being environmentally benign (in gen...

The present study combines, for the first time, experimental degradation findings and numerical simulation results of CCl4 sonochemistry for (i) understanding the right mechanism by which CCl4 improves Safranin O (SO) sono-bleaching (1.7 MHz, 15 W) and (ii) stating the impact of operational conditions on reactive species dis- tribution toward the...

To anticipate emulsion breakdown in the ELM process, the Box–Behnken design was used with an artificial neural network (ANN) and a metaheuristic approach, namely particle swarm optimization (PSO) and response surface methodology (RSM). Membrane stability testing began with an experimental component to collect data. The following parameters were use...

Power ultrasonic (> 100 kHz) splits water into free radicals and hydrogen. As a result, water sonochemistry is considered as an alternative clean and fossil-fuel-free hydrogen production technique. In this research work, the impact of rare gases (Xe, Ar, and He) on the sonochemical production of hydrogen as well as the population of active bubbl...

In this work, after exploring the first report on the synergism of combining ultrasound (US: 600 kHz) and chlorine toward the degradation of Allura Red AC (ARAC) textile dye, as a contaminant model, the impact of various mineral water constituents (Cl–, SO42–, NO3–, HCO3– and NO2–) and natural organic matter, i.e., humic acid (HA), on the performan...

For the objective of establishing a large vision on the limits of hydroxylamine-induced acceleration of the Fenton process, the impact of wide range of processing conditions and water matrix composition...

A comprehensive numerical investigation was conducted to analyze the effect of ultrasound frequency (213-1000 kHz), ultrasonic intensity (0.7-1.5 W/cm 2) and medium temperature (293.15-333.15 K) on the production of hydrogen from methanol decomposition inside acoustic bubbles (methanol sono-conversion). The adopted model was firstly compared with s...

The present paper introduces a novel semi-empirical technique for the determination of active bubbles’ number in sonicated solutions. This method links the chemistry of a single bubble to that taking place over the whole sonochemical reactor (solution). The probe compound is CCl4, where its eliminated amount within a single bubble (though pyrolysis...

A number of theoretical and experimental works showed the possibility of increasing the sonochemical production of hydrogen through the pyrolysis of methanol within the acoustic cavitation (i.e. sonolysis of aqueous methanol solution). In this study, numerical simulations have been conducted in order to reveal, for the first time, the effect of met...

Carbon Tetrachloride (CCl 4 ) has a versatile role in sonochemistry, e.g., self�degradation, accelerator of ● OH radical production, and reactive chorine radical generator. These example aspects arise from the pyrolysis of CCl 4 inside acoustic bubbles. A model of CCl 4 sono-pyrolysis inside an acoustic bubble is used to provide a novel mechanistic...

In this paper, the degradation of the diazo dye naphthol blue black (NBB) using the Galvano-Fenton process is studied experimentally and numerically. The simulations are carried out based on the anodic, cathodic, and 34 elementary reactions evolving in the electrolyte, in addition to the oxidative attack of NBB by HO• at a constant rate of 3.35×107...

In addition to bubble number density, bubble size distribution is an important population parameter governing the activity of acoustic cavitation bubbles. In the present paper, an iterative numerical method for equilibrium size distribution is proposed and combined to a model for bubble counting, in order to approach the number density within a pop...

The present paper investigates the potential of the Galvano-Fenton process as an advanced technique in terms of the simultaneous oxidation of a model pollutant, phenol, and the energy release and saving as compared to conventional electrochemical techniques, namely, Fenton, Fenton-like, and Electro-Fenton. A numerical model describing the electroch...

A novel approach allowing the production of electrical energy by an advanced oxidation process is proposed to eliminate organic micropollutants (MPs) in wastewaters. This approach is based on associating the Galvano–Fenton process to the generation of electrical power. In the previous studies describing the Galvano–Fenton (GF) process, iron was dir...

UV/periodate (IO ⁻ 4 ) process is one of the recent advanced oxidation processes (AOPs) that have been efficiently applied to degrade various persistent organic pollutants and lower chemical oxygen demand in industrial wastewater. The photo-irradiation of periodate (λ < 400 nm) in aqueous solutions can produce several reactive radicals and non-radi...

The present chapter addresses the place of ultrasound and sonochemistry in water remediation applications, the panoply of effects generated by ultrasound travelling across wastewater are discussed in regards to their nature, i.e. physical and chemical, and impact, water disinfection and chemical oxidation. The mechanisms of action of ultrasound ran...

The cationic dye safranin-O was removed from an aqueous solution using the Emulsion Liquid membrane (ELM) method. The ELM system consists of a diluent (hexane) and a surfactant (Span 80). Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters regulating the safranin-O dye removal were investigated. Twenty-nine (29)...

The cationic dye safranin-O was removed from an aqueous solution using the Emulsion Liquid membrane (ELM) method. The ELM system consists of a diluent (hexane) and a surfactant (Span 80). Sulfuric acid (H2SO4) solution was used as an internal aqueous phase. The key parameters regulating the safranin-O dye removal were investigated. Twenty-nine (29)...

Sonochemistry is considered as one of the cleaner pathways for hydrogen production. The present paper investigates the potential of this technique based upon mass, mass to energy and energy conversion metrics, using modelling and experimental approaches. Four scenarios are examined assuming four saturating gases, namely O2, air, N2 and Ar, four aco...

It is known that the evaporation of carbon tetrachloride (CCl4) into the acoustic cavitation during water sonolysis results in the generation of many reactive species (e.g. chlorinated elements), probable reduction of bubble temperature and the scavenging of hydrogen atom by its reaction with CCl4. Consequently, the chemistry of bubbles (sono-activ...

In spite of the great number of experimental works conducted on CCl4 sono-degradation, several controversies are observed, these including the main species generated upon CCl4 decomposition and the mechanism by which CCl4 accelerated the sonolytic removal of nonvolatile contaminates. In this paper, a new mechanism of carbon tetrachloride pyrolysis...

Several experimental and computational works have been focused on the production of hydrogen by using ultrasonic irradiation. However, the effects of the different ultrasonic conditions have been analyzed by considering a single value for the ambient bubble radius R0 (mean value), which is not the true case as the size of active bubbles in sonicati...

Numerical simulations have been performed on a range of ambient bubble radii, in order to reveal the effect of mass transport, heat exchange and chemical reactions heat on the chemical bubble yield of single acoustic bubble. The results of each of these energy mechanisms were compared to a normal model in which all these processes (mass transport,...

The effect of static pressure (P∞) on.bubble.sonochemistry (i.e. hydrogen and reactive species production) is investigated on a range of ambient bubble sizes (R0) for argon-saturated water. The used ambient pressure ranges from 0.3 to 2 atm, where its impact is shown for frequencies of 355, 500 and 1000.kHz. It is found that for each ambient pressu...

In the present study, the kinetics of degradation of acid orange 7 (AO7) by the Galvano-Fenton process is assessed experimentally and simulated numerically in order to figure out the mechanism of generation and consumption of free radicals with this novel advanced oxidation process. 10 mg/L of the azo dye are degraded during 20 min by combining a c...

The present study treats the effects of mass transport, heat transfer and chemical reactions heat on the bubble dynamics by spanning a range of ambient bubble radii. The thermodynamic behavior of the acoustic bubble was shown for three wave frequencies, 355, 515 and 1000 kHz. The used acoustic amplitude ranges from 1 to 3 atm. It has been demonstra...

The acoustic cavitation bubble as an open energetic system is the seat of conversion of various forms of energy accompanying the bubble oscillation. The energy conversion would explain specific dynamical, thermal and kinetical behaviors. In the present paper, the energy balance related to a stable bubble irradiated by dual-frequency field is simula...

The present paper reports a numerical investigation of the feasibility of a hybrid concept associating the 1-Butyl-3-methylimidazolium Acetate [C4mim][CH3COO] to sonication, in terms of cavitation formation and generated extreme conditions allowing cellulose decomposition in the second reactivity site. The results of the proposed model revealed an...

Owing to the stability and resistance to biodegradation of synthetic dyes, their elimination from industrial wastewater is a very difficult task. This problem has triggered environmental engineers and scientists to search for innovative solutions. Over the last two decades, considerable attention has been paid to the use of ultrasound as an alterna...

Sonolysis and ozonation are two advanced oxidation processes (AOPs) that are actually well documented and their mechanisms are well established. Recently, the combination of these two processes, that is sonolytic ozonation [ultrasound (US)/O3], has been successfully applied to improve the degradation of several water contaminants, as compared to ea...

Both sonolysis and heat-activated persulfate (HAPS) are effective advanced oxidation processes (AOPs) for the destruction of organic pollutants in wastewater. Although ultrasound can activate persulfate at ambient temperature, the synergy between ultrasound and HAPS was poorly investigated, especially when megahertz frequency ultrasound is used. Th...

Acoustic cavitation is the central event of the sonochemical process, which is one of the most recent advanced oxidation processes for water treatment. Even though the liquid compressibility effect on acoustic cavitation has already been investigated by certain studies, their results are still limited to the radial dynamics and the thermodynamic be...

Acoustic cavitation is the central event of water sonolysis, which generates several radical and nonradical species such as H•, •OH, H2, and H2O2. In addition to these species, production of HNO2 and HNO3 was demonstrated in N2-containing aqueous solutions. These species were usually liberated as nitrite and nitrate ions. The mechanism by which NO2...

Injecting of soluble gases in water under sonication is an important tool for improving the efficiency of the sonochemical treatment of water. Among several used gases, nitrous oxide (N2O) has shown a special effect. Instead other gases, dissolving pure N2O in solutions suppresses all sonochemical effects. However, when low amount of this gas is in...

The mechanism by which seawater salts affect the sonochemical activity is until now under debate. In this work, a theoretical approach based on single bubble sonochemistry model has been adopted for examining the effect of seawater salinity on the acoustic generation of free radicals. The model combines the fluctuation dynamics of single acoustic b...

In the present work, the Paracentrotus lividus spines (PLS) are proposed as a novel low-cost non-conventional adsorbent for the removal of malachite green (MG) from aqueous phases in the absence and presence of ultrasonic irradiation and by combining simultaneously ultrasound and mechanical agitation. The PLS was characterized by Fourier transform...

Photocatalysis and sonolysis are two advanced oxidation processes, which are actually well documented and their mechanisms are well established. Recently, the combination of these two processes, i.e., sonophotocatalysis, has shown a potential application for the degradation of persistent organic dyes. This hybrid process has mostly shown a synergis...

The paper presents a numerical modeling approach predicting the sonochemical efficiency for water decontamination integrally based on micro‐scale activity of a single bubble, coupled to macro‐scale energetic balance on a batch sonochemical reactor volume. The sonochemical efficiency is axed on the powerful oxidative effect of HO• radicals on organi...

This paper presents the first modeling study on UV/periodate (IO4–) advanced oxidation process. A reaction mechanism consisting in 45 chemical reactions including a number of radicals (IO3•, IO4•, •OH, O•–, HO2•, O2•–, O3•–) and non-radical intermediates/products (O(3 P), O3, IO3–, H2O2, HO2–, I2O6 and I2O8) has been developed to assess the reactiv...

Although most of researchers agree on the elementary reactions behind the sonolytic formation of molecular hydrogen (H2) from water, namely the radical attack of H2O and H2O2 and the free radicals recombination, several recent papers ignore the intervention of the dissolved gas molecules in the kinetic pathways of free radicals, and hence may wrong...

The present paper constitutes a conjugate numerical and experimental study of a novel process patented as Galvano-Fenton, based on the association of galvanic corrosion and Fenton reaction. The study investigates the pathways of the in-situ formation and regeneration of iron species involved in electrochemical and chemical mechanisms of the Galvano...

In this study, a dynamic mathematical model for direct contact membrane distillation (MD) is developed and validated. Two model formulations were considered each of which can be cast in lumped or spatial structure. All types of models were verified against experimental transient data for the permeate and brine temperatures. The proposed models prov...

La ciprofloxacine (CIP) fait partie de la famille des fluoroquinolones qui sont des antibiotiques fréquemment utilisés en prescription médicale courante car ils possèdent un bon profil de tolérance, une excellente biodisponibilité et un large spectre antibactérien. Les effets secondaires de la CIP sont pour la plupart des réactions attendues : gast...

The present work consists of an innovative approach aiming to address the scalability dilemma of the sonochemical activity dependency of acoustic frequency. The study originates from the discordance of observations between the theoretical investigations of the sonochemical activity of the single acoustic cavitation bubble in function of the acousti...

The impact of various mineral anions, diverse organic substrates and different environmental matrices on the removal of C.I. reactive green 12 (RG12) refractory textile dye by UV/chlorine emerging advanced oxidation process (AOP) was performed. The co-exposure of RG12 (20 mg L⁻¹) to UV and chlorine (0.5 mM) at pH 5 produced a strong synergism on th...

In this work, we have explored for the first time the potential application of trace‐Fe(III)/chlorine system as an innovative oxidation technology for the degradation of persistent textile dyes. Fe(III)/chlorine combination improved the dye removal by ~40% within 30 s, as compared with chlorination alone, mainly through a radical pathway induced by...

The present paper consists of a numerical simulation that investigates the opportunity to treat wastewater contaminated with methanol by sonolysis. The technique offers a double benefit in regards to two axes: methanol degradation and hydrogen emergence. The adopted model based on the simultaneous evolutions of bubble dynamics, physical and chemica...

Even through the liquid compressibility effect on acoustic cavitation has already been investigated by several authors, their results, however, are still limited to the radial dynamics and the thermodynamic behavior of the gas inside the bubble. In this computational study, the effect of liquid compressibility was investigated on both the bubble dy...

Among various applied aspects of sonochemistry, the sonochemical production of hydrogen is of great interest, although available experimental data on this field is in general very limited. Sonochemistry is an environmentally friendly area of chemistry where chemical reactions are induced by ultrasound waves in the range of 20–1000 kHz. This review...

The synergy of applying UV/chlorine advanced oxidation process (AOP) for the degradation of organic pollutants was usually reported. However, very limited information is available on the influence of processing conditions on the resulted synergism. In this work, C.I. reactive green 12 (RG12), a refractory textile dye, has been selected as a polluta...

The discovery of sonochemistry and the advent of green processing concept occurred with a time difference of almost four decades and one-step ahead for sonochemistry. Yet sonochemistry is often winded for its green character. For sure, sonochemistry was not first implemented in this perspective, which suggests a “benign-by-design process.” This ide...

This paper describes the intercalation of ciprofloxacin (CIP), a bactericidal antibiotic, into the interlayer space of layered double hydroxides (LDH). To counter the problem of bacterial resistance and also to improve the properties of CIP drug, the drug carrier approach promises significant benefits. Through a tightly control of the synthesis par...

This work is focused on the combination of classic and modified (ultrasound-assisted) of the Fenton process, for the treatment of water contaminated by an azo dye. The experiments presented herein were carried out on naphthol blue black (NBB), and the obtained results demonstrate a remarkable elimination attaining 99%. The influence of different op...

We have recently reported that the reaction of H2O2/IO4⁻ could be a new advanced oxidation process (AOP) for water treatment [N. E. Chadi, S. Merouani, O. Hamdaoui, M. Bouhelassa and M. Ashokkumar, H2O2/periodate (IO4⁻): a novel advanced oxidation technology for the degradation of refractory organic pollutants, Environ. Sci.: Water Res. Technol., 2...

BACKGROUND Carbon dioxide (CO2) is a gas that has a distinguished effect on the sonochemical process. Dissolving pure CO2 in solutions prevented sonochemical action in all laboratory‐scale experiments, reported until know. The mechanism underlying the pure‐CO2 nullifying sonochemical treatment is until now under debate. RESULTS Herein, thanks to c...

The present paper consists of a numerical study attempting to characterize the bubble population within a sonochemical reactor through modeling and simulating the number density of bubbles and the void fraction. In a first step, both previous parameters were estimated under 1.52 bar and various acoustic frequencies ranging from 20 to 1000 kHz in fu...

The sonochemical activity of an oxygen bubble formed in an aqueous medium and oscillating under a dual-frequency excitation is studied in this paper. Several couples of frequencies are formed amongst 35, 140, 300 and 515 kHz, with a maximum acoustic amplitude of 1.5 atm. The molar yields of the emerging oxidants are analyzed in accordance with the...

The objective of the present numerical study is to examine the sonochemical production within a single acoustic bubble that oscillates in an aqueous methanol solution under an oxygen-argon mixture. The produced molar yield during the strong collapse was analyzed in accordance with the system composition, i.e. the molar fraction of argon and the vol...

Herein, we show the first report on the degradation of hazardous organic pollutants in very saline matrice (seawater) using acetone photoactivated process at 253.7 nm. Chloral black (CB), a very persistent dye of well‐established carcinogenic and mutagenic effects, was chosen a substrate model. The photodegradation of CB was monotonically increased...

The project aim on the development of intercalated compounds based on layered double hydroxide (LDH) materials as carriers of bioactive species.

Owing to the marked stability and resistance to biodegradation of synthetic dyes, their removal from industrial wastewater is a very difficult process. Herein, we investigated the feasibility of Fe(II)/chlorine system to remove synthetic dyes from water. It was found that the presence of chlorine in solution containing 25 µM of Fe(II) at pH 5 accel...

This study demonstrated, for the first time, that the H2O2/IO4⁻ system could be an efficient advanced oxidation process (AOP) for wastewater treatment. Batch experiments conducted under ambient conditions with toluidine blue (TB), as a model pollutant, showed that 98% of TB and 73% of the initial total organic carbon were removed after only 1 min o...

In recent years, ozonation combined with ultrasound (US/O 3 process) has been actively researched as a promising method of advanced oxidation processes. Comparing with ozonation or ultrasound alone, it appears to be more effective and uses less energy, and it has the advantages of being nonselective, leading to no secondary pollution, and being par...

The present paper constitutes an objective review and a constructive analyze of the main bibliographic results regarding the production of hydrogen using ultrasound. In spite of clear trends showing the efficiency of sonolysis for H2 production, as compared to conventional techniques, reported by several authors, many debates are still opened regar...

Understanding the effect of the liquid depth (z) on the acoustic generation of hydrogen is highly required for designing large-scale sonoreactors for hydrogen production because acoustic cavitation is the central event that initiates sonochemical reactions. In this paper, we present a computational analysis of the liquid-depth effect on the generat...

The results presented in this study illustrate the multiple roles of seawater salinity toward the sonochemical degradation, at variable frequencies (300-1700kHz), of several hazardous substances, i.e. propylparaben (PPR) endocrine disruptor and several synthetic dyes: naphthol blue black (NBB), malachite green (MG), basic red 29 (BR29), acid orange...

This study examined the effect of different mineral and organic additives on the degradation of Chlorazol Black (CB, 25.5 μM) in aqueous media by UV/acetone process. Initially, it was found that acetone (50 mM)-assisted UV irradiation accelerated the CB removal within 30 min to 98% against 34% for the sole UV, presumably due to the implication of m...

A particular case of harmonics excitation using ultrasonic waves with the frequencies of 200, 300 and 500 kHz at an acoustic amplitude of 2 atm is numerically investigated in the present paper, as a new method aiming to improve the sonochemical production of hydrogen within active cavitation bubble. The modification of the conventional sine signal,...

This work aimed at the characterization and application of a cavitation field induced in water by an ultrasonic reactor operating at 1700 kHz and 15 W. It was found that the size of active bubbles varied from 0.23 to 3 µm. The number of active bubbles increased from 6.1142 × 108 s−1 L−1 at 25 °C to 4.4684 × 109 s−1 L−1 at 55 °C. The most active bub...