Effect of nitrate ions on the efficiency of sonophotochemical phenol degradation

A sonophotochemical oxidation process has been used for the treatment of an aqueous solution of phenol. The aim of this work is to evaluate the effect of nitrate ions on hydroxyl radical production and on phenol oxidation. It has been demonstrated that ultrasound can produce NOx (nitrate and nitrite), with a production rate of 2.2 μM min⁻¹. The photolysis of nitrate can significantly improve the hydroxyl radical production. The apparent rate constant for hydroxyl radical production increased from 0.0015 min⁻¹ to 0.0073 min⁻¹ while increasing initial nitrate concentration from 0 to 0.5 mM. The concentration of hydroxyl radical was directly proportional to the initial nitrate concentration. Using US/UV process, the apparent reaction rate constant of phenol degradation in the presence of nitrate reached 0.020 min⁻¹, which was relatively lower than the value obtained (0.027 min⁻¹) in the absence of nitrate. It appeared that, nitrate ions can inhibit the sonochemical degradation of organic compounds such as phenol.     

Sonocatalyzed decolorization of synthetic textile wastewater using sonochemically synthesized MgO nanostructures

The present study focused on the synthesis of nanostructured MgO via sonochemical method and its application as sonocatalyst for the decolorization of Basic Red 46 (BR46) dye under ultrasonic irradiation. The sonocatalyst was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray microanalysis (EDX). In the following, the sonocatalytic removal of the dye under different operational conditions was evaluated kinetically on the basis of pseudo first-order kinetic model. The reaction rate of sonocatalyzed decolorization using MgO nanostructures (12.7 × 10⁻³ min⁻¹) was more efficient than that of ultrasound alone (2.0 × 10⁻³ min⁻¹). The increased sonocatalyst dosage showed better sonocatalytic activity but the application of excessive dosage should be avoided. The presence of periodate ions substantially increased the decolorization rate from 14.76 × 10⁻³ to 33.4 × 10⁻³ min⁻¹. Although the application of aeration favored the decolorization rate (17.8 × 10⁻³ min⁻¹), the addition of hydrogen peroxide resulted in a considerable decrease in the decolorization rate (9.5 × 10⁻³ min⁻¹) due to its scavenging effects at specific concentrations. Unlike alcoholic compounds, the addition of phenol had an insignificant scavenging effect on the sonocatalysis. A mineralization rate of 7.4 × 10⁻³ min⁻¹ was obtained within 120 min. The intermediate byproducts were also detected using GC–MS analysis.     

Ultrasonically controlled growth of monodispersed octahedral BiVO4 microcrystals for improved photoelectrochemical water oxidation

The synthesis of facet-controlled structures with precise morphology and exposed reactive surface is one of the key research challenges. We effectively endeavoured to obtain the monodisperse octahedral bismuth vanadate microcrystals with exposed {1 0 1},{2 0 0},{3 1 2} and {0 2 1} dominant facets through an optimized sonochemical assisted hydrothermal process. A pulse sonication (5-s ON and 2-s OFF cycle, 21 W ultrasonic power and 20 kHz ultrasonic frequency) for 30 mins followed by 1 h hydrothermal treatment was found to yield the preferred octahedral morphology. The microscopic and X-ray analysis suggested a potent role of ultrasonic waves for the initial seed growth and its evolution into a well-defined monodisperse microcrystals. The density functional theory (DFT) calculations revealed strongly localized bandgap states with a bandgap of ~2.47 eV. The PEC measurements for water oxidation demonstrated the efficacy of these microcrystals as photoanode. Notably, the optimized octahedral BiVO₄ microstructure exhibited a superior performance as evident from photocurrent density ~0.9 mAcm⁻² at 1.23 V vs. RHE and %IPCE value of ~22% compared to analogous photoanodes under visible light irradiation.     

Improvement of sonochemical degradation of Brilliant blue R in water using periodate ions: Implication of iodine radicals in the oxidation process

In this paper, the effect of periodate (IO₄⁻) on the ultrasonic degradation at 300 kHz of Brilliant Blue R (BBR), an organic dye pollutant, was investigated. The experiments were realized in the absence and presence of periodate for various operating conditions including initial solution pH (2–8) and delivered ultrasonic power (20–80 W). It was found that periodate greatly enhanced the sonochemical degradation of BBR. The degradation rate increased significantly with increasing IO₄⁻ concentration up to 10 mM and decreased afterward. With 10 mM of periodate, the degradation rate was 2.4-fold higher than that with ultrasound alone. The chemical probes experiments showed that periodate activation into free radicals (IO₃, IO₄ and OH) takes place by sonolysis and iodine radicals contribute significantly in the oxidation process. It was found that the periodate-enhanced effect was strongly experimental parameters dependent. The advantageous effect of periodate increased significantly with decreasing power and the best enhancing effect was obtained for the lowest power. Correspondingly, the periodate-enhanced effect increased with pH increase in the range 2–8 and it was more remarkable at near alkaline condition (pH 8). A reaction scheme for periodate sonolysis was proposed, for the first time, discussed and then used for interpreting the obtained results.     

Medium-high frequency ultrasound and ozone based advanced oxidation for amoxicillin removal in water

In this study, treatment of an antibiotic compound amoxicillin by medium-high frequency ultrasonic irradiation and/or ozonation has been studied. Ultrasonic irradiation process was carried out in a batch reactor for aqueous amoxicillin solutions at three different frequencies (575, 861 and 1141 kHz). The applied ultrasonic power was 75 W and the diffused power was calculated as 14.6 W/L. The highest removal was achieved at 575 kHz ultrasonic frequency (>99%) with the highest pseudo first order reaction rate constant 0.04 min⁻¹ at pH 10 but the mineralization achieved was around 10%. Presence of alkalinity and humic acid species had negative effect on the removal efficiency (50% decrease). To improve the poor outcomes, ozonation had been applied with or without ultrasound. Ozone removed the amoxicillin at a rate 50 times faster than ultrasound. Moreover, due to the synergistic effect, coupling of ozone and ultrasound gave rise to rate constant of 2.5 min⁻¹ (625 times higher than ultrasound). In the processes where ozone was used, humic acid did not show any significant effect because the rate constant was so high that ozone has easily overcome the scavenging effects of natural water constituents. Furthermore, the intermediate compounds, after the incomplete oxidation mechanisms, has been analyzed to reveal the possible degradation pathways of amoxicillin through ultrasonic irradiation and ozonation applications. The outcomes of the intermediate compounds experiments and the toxicity was investigated to give a clear explanation about the safety of the resulting solution. The relevance of all the results concluded that hybrid advanced oxidation system was the best option for amoxicillin removal.     

Intercalation and exfoliation behavior of carbon fibers during electrolysis in H2SO4

Electrochemical preparation of intercalation compounds of carbon fibers in sulfuric acid solutions and their exfoliation were studied. Effect of the concentration of sulfuric acid on the intercalation was examined. In low concentration of sulfuric acid solutions, the formation of intercalation compound and subsequent exfoliation were accelerated. By rapid heating at 1000 °C, the residue compounds of carbon fibers formed by electrolysis in 2.3–9.0 mol dm⁻³ were found to exfoliate and showed marked morphological changes. In high concentration electrolytes, however, the formation of intercalation compounds of carbon fibers and their exfoliation were depressed. The successful intercalation in low concentration electrolytes might be due to oxygen generated by anodic polarization, which resulted in marked exfoliation.     

Intensification of sonochemical degradation of ammonium perfluorooctanoate by persulfate oxidant

Ammonium perfluorooctanoate (APFO) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. The decomposition of APFO in aqueous solution with a combination of persulfate oxidant and ultrasonic irradiation was investigated. The effects of operating parameters, such as ultrasonic power, persulfate concentration, APFO concentration, and initial media pH on APFO degradation were discussed. In the absence of persulfate, 35.5% of initial APFO in 46.4 μmol/L solution under ultrasound irradiation, was decomposed rapidly after 120 min with the defluorination ratio reaching 6.73%. In contrast, when 10 mmol/L persulfate was used, 51.2% of initial APFO (46.4 μmol/L) was decomposed and the defluorination ratio reached 11.15% within 120 min reaction time. Enhancement of the decomposition of APFO can be explained by acceleration of substrate decarboxylation, induced by sulfate radical anions formed from the persulfate during ultrasonic irradiation. The SO₄^−•/APFO reactions at the bubble-water interface appear to be the primary pathway for the sonochemical degradation of the perfluorinated surfactants.     

Calorimetric studies of NO on Ni{2 1 1}: criteria for switching from dissociative to molecular adsorption

The coverage-dependent heats of adsorption and sticking probabilities in the interaction of nitric oxide with clean and oxygen pre-covered Ni{2 1 1} surfaces have been measured at 300 K using single crystal adsorption calorimetry. The results are consistent with a switch from dissociative to molecular chemisorption at 1 ML of O plus N adatoms. Initial dissociative adsorption is attributed to step sites with a heat of 400 kJ mol⁻¹. When steps are saturated with adatoms, adsorption proceeds molecularly with a heat of 160 kJ mol⁻¹. With 0.24 ML oxygen adatom pre-coverage, the initial heat is only 250 kJ mol⁻¹ and with 0.6 ML oxygen adatom, NO adsorption is only molecular with an initial heat of 160 kJ mol⁻¹. The NO sticking probability behaviour is consistent with this picture, with successive precursor mediated adsorption at step and terrace sites. The inhibition of dissociation above O, or O plus N, adatom coverages of 1 ML is attributed to the strong lateral repulsive interactions between adatoms, which would drive the dissociative heat of adsorption below that of molecular adsorption at higher coverages.     

Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone in airlift sonochemical reactor

Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone was studied in a new type reactor – the airlift loop sonochemical reactor. The reactor plays a synergistic effect of sonochemsity and higher oxygen transfer rate. The influences of ultrasound intensity, reaction temperature, the molar ratio of benzaldehyde to cyclohexanone and oxygen gas flow rate on the conversion and selectivity of cyclohexanone were investigated and discussed. Under ultrasound, the amount of benzaldehyde can be reduced from 75% to 67%. Ultrasound not only intensified the rates of reactions but also increased the yield of product. The optimized operation conditions are listed as follows: the reaction temperature is 30 °C, the molar ratio of cyclohexanone to benzaldehyde is 1:2, the oxygen gas flow rate is 1.15 cm s⁻¹, and ultrasonic irradiations 2 h at 40 kHz, 2.25 W cm⁻². Under the optimum operation conditions, the average molar yield of ε-caprolactone comes up to 87.7%.     

Sonochemical characterisation of ultrasonic dental descalers

An ultrasonic dental descaling instrument has been characterised using sonochemical techniques. Mapping the emission from luminol solution revealed the distribution of cavitation produced in water around the tips. Hydroxyl radical production rates arising from water sonolysis were measured using terephthalate dosimetry and found to be in the range of μmol min⁻¹, comparable with those from a sonochemical horn. Removal of an ink coating from a glass slide showed that cleaning occurred primarily where the tip contacted the surface but was also observed in regions where cavitation occurred even when the tip did not contact the surface. Differences in behaviour were noted between different tip designs and computer simulation of the acoustic pressure distributions using COMSOL showed the reasons behind the different behaviour of the tip designs.     

Ultrasound-promoted dispersive micro solid-phase extraction of trace anti-hypertensive drugs from biological matrices using a sonochemically synthesized conductive polymer nanocomposite

In this work, a rapid and efficient procedure named ultrasound meliorated dispersive micro solid-phase extraction followed by high performance liquid chromatography-ultra violet detection (US-D-μSPE-HPLC-UV) was developed for the pre-concentration of the main trace anti-hypertensive drugs in complex matrices. The basis of this procedure was a polypyrrole-sodium dodecylbenzenesulfonate/zinc oxide (PPy-DBSNa/ZnO) nanocomposite. It was readily synthesized by the impressive way of in situ sonochemical oxidative polymerization in the presence of some additives such as FeCl₃ and DBSNa, ultimately leading to the effective coating of PPy on the ZnO nanoparticle cores. Characterization of the proposed nanosorbent was performed by different techniques such as FESEM, XRD,EDX, and TGA, confirming the high quality and proper physico-chemical properties of the proposed sorbent. In order to better investigate the input variables, the central composite design (CCD) combined with the desirability function (DF) was utilized. The enriched optimum conditions consisted of the initial pH value of 11.8, 15 mg of the PPy-DBSNa/ZnO nanocomposite, a sonication time of 4.6 min, and 100 μL of methanol, resulting in maximum responses at a relatively low extraction time with a logical DF. Under the optimum conditions, good linearity (5–5000, 2.5–3500, and 2.5–3000 ng mL⁻¹ for metoprolol, propranolol, and carvedilol, respectively, with the correlation of determinations (R²s) higher than 0.99), low limits of detection (LODs) (0.8–1.5 ng mL⁻¹), proper repeatabilities (relative standard deviation values (RSDs) below 6.3%, n = 3), reasonable enrichment factors (EFs) (60–72), and good extraction recoveries (ERs) (higher than %75) were obtainable. These appropriate validations corroborated a good effectiveness of ultrasonic waves in the achievement of a supreme solid phase as well as a facile and efficient microextraction of the low therapeutic concentrations in human plasma and urine samples.     

Synergistic effects of combining ultrasound with the Fenton process in the degradation of Reactive Blue 19

The decoloration of reactive dye C.I. Reactive Blue 19 (RB 19) using combined ultrasound with the Fenton process has been investigated. The effect of varying the concentrations of hydrogen peroxide and iron sulfate, initial pH, ultrasonic power, initial dye concentration and dissolved gas on the decoloration and degradation efficiencies was measured. Calibration of the ultrasound systems was performed using calorimetric measurements and oxidative species monitoring using the Fricke dosimeter and degradations were carried out with a 20 kHz probe type transducer at 2, 4, 6 and 8 W cm⁻² of acoustic intensity at 15, 25, 50 and 75 mg L⁻¹ initial dye concentrations. First order rate kinetics was observed. It was found that while the degradation rate due to ultrasound alone was slow, sonication significantly accelerated the Fenton reaction. While the results were similar to those reported for other dyes, the effects occurred at lower concentrations. The rate and extent of decoloration of RB 19 increased with rising hydrogen peroxide concentration, ultrasonic powers and iron sulfate concentration but decreased with increasing dye concentration. An optimum pH value of pH = 3.5 was found. The rate of decoloration was higher when dissolved oxygen was present as compared with nitrogen and argon confirming the solution phase mechanism of the degradation.     

Sonochemical synthesis of LiNi0.5Mn1.5O4 and its electrochemical performance as a cathode material for 5 V Li-ion batteries

LiNi_0.5Mn_1.5O₄ was synthesized as a cathode material for Li-ion batteries by a sonochemical reaction followed by annealing, and was characterized by XRD, SEM, HRTEM and Raman spectroscopy in conjunction with electrochemical measurements. Two samples were prepared by a sonochemical process, one without using glucose (sample-S1) and another with glucose (sample-S2). An initial discharge specific capacity of 130 mA h g⁻¹ is obtained for LiNi_0.5Mn_1.5O₄ at a relatively slow rate of C/10 in galvanostatic charge–discharge cycling. The capacity retention upon 50 cycles at this rate was around 95.4% and 98.9% for sample-S1 and sample-S2, respectively, at 30 °C.     

Evaluation on the air-borne ultrasound-assisted hot air convection thin-layer drying performance of municipal sewage sludge

The thin-layer drying behavior of the municipal sewage sludge in a laboratory-scale hot air forced convective dryer assisted with air-borne ultrasound was investigated in between 70 and 130 °C hot air temperatures. The drying kinetics in the convective process alone were compared to that for ultrasound-assist process at three ultrasound powers (30, 90, 150 W). The average drying rates within whole drying temperature range at ultrasound powers of 30, 90 and 150 W increased by about 22.6%, 27.8% and 32.2% compared with the convective drying alone (without ultrasound). As the temperature increasing from 70 °C to 130 °C, there were maximum increasing ratios for the effective moisture diffusivities of the sewage sludge in both falling rate periods at ultrasonic power of 30 W in comparison with other two high powers. In between the ultrasound powers of 0 and 30 W, the effect of the power on the drying rate was significant, while its effect was not obvious over 30 W. Therefore, the low ultrasonic power can be just set in the drying process. The values of the apparent activation energy in the first falling rate period were down from 13.52 to 12.78 kJ mol⁻¹, and from 17.21 to 15.10 kJ mol⁻¹ for the second falling rate period with increasing the ultrasonic power from 30 to 150 W. The values of the apparent activation energy in two falling rate periods with the ultrasound-assist were less than that for the hot air convective drying alone.     

Rapid preparation of high electrochemical performance LiFePO4/C composite cathode material with an ultrasonic-intensified micro-impinging jetting reactor

A joint chemical reactor system referred to as an ultrasonic-intensified micro-impinging jetting reactor (UIJR), which possesses the feature of fast micro-mixing, was proposed and has been employed for rapid preparation of FePO₄ particles that are amalgamated by nanoscale primary crystals. As one of the important precursors for the fabrication of lithium iron phosphate cathode, the properties of FePO₄ nano particles significantly affect the performance of the lithium iron phosphate cathode. Thus, the effects of joint use of impinging stream and ultrasonic irradiation on the formation of mesoporous structure of FePO₄ nano precursor particles and the electrochemical properties of amalgamated LiFePO₄/C have been investigated. Additionally, the effects of the reactant concentration (C = 0.5, 1.0 and 1.5 mol L⁻¹), and volumetric flow rate (V = 17.15, 51.44, and 85.74 mL min⁻¹) on synthesis of FePO₄·2H₂O nucleus have been studied when the impinging jetting reactor (IJR) and UIJR are to operate in nonsubmerged mode. It was affirmed from the experiments that the FePO₄ nano precursor particles prepared using UIJR have well-formed mesoporous structures with the primary crystal size of 44.6 nm, an average pore size of 15.2 nm, and a specific surface area of 134.54 m² g⁻¹ when the reactant concentration and volumetric flow rate are 1.0 mol L⁻¹ and 85.74 mL min⁻¹ respectively. The amalgamated LiFePO₄/C composites can deliver good electrochemical performance with discharge capacities of 156.7 mA h g⁻¹ at 0.1 C, and exhibit 138.0 mA h g⁻¹ after 100 cycles at 0.5 C, which is 95.3% of the initial discharge capacity.     

Ultrasonic-assisted degradation of phenazopyridine with a combination of Sm-doped ZnO nanoparticles and inorganic oxidants

Pure and samarium doped ZnO nanoparticles were synthesized by a sonochemical method and characterized by TEM, SEM, EDX, XRD, Pl, and DRS techniques. The average crystallite size of pure and Sm-doped ZnO nanoparticles was about 20 nm. The sonocatalytic activity of pure and Sm-doped ZnO nanoparticles was considered toward degradation of phenazopyridine as a model organic contaminant. The Sm-doped ZnO nanoparticles with Sm concentration of 0.4 mol% indicated a higher sonocatalytic activity (59%) than the pure ZnO (51%) and other Sm-doped ZnO nanoparticles. It was believed that Sm³⁺ ion with optimal concentration (0.4 mol%) can act as superficial trapping for electrons in the conduction band of ZnO and delayed the recombination of charge carriers. The influence of the nature and concentration of various oxidants, including periodate, hydrogen peroxide, peroxymonosulfate, and peroxydisulfate on the sonocatalytic activity of Sm-doped ZnO nanoparticles was studied. The influence of the oxidants concentration (0.2–1.4 g L⁻¹) on the degradation rate was established by the 3D response surface and the 2D contour plots. The results demonstrated that the utilizing of oxidants in combination with Sm-doped ZnO resulting in rapid removal of contaminant, which can be referable to a dual role of oxidants; (i) scavenging the generated electrons in the conduction band of ZnO and (ii) creating highly reactive radical species under ultrasonic irradiation. It was found that the Sm-doped ZnO and periodate combination is the most efficient catalytic system under ultrasonic irradiation.     

Studies on the effect of chlorides of magnesium,calcium, strontium and barium on the temperature of the sound velocity maximum of water

The effect of chlorides of magnesium, calcium, strontium and barium on the temperature of the sound velocity maximum (TSVM) of water, T_w, has been studied by determining the ultrasonic velocity using a single crystal variable path interferometer working at 3 MHz. The accuracy in ultrasonic velocity measurement is ± 0.05 m s^− 1. The ultrasonic velocity measurements were carried out at ≃ 2 °C intervals over a range of 5 °C to either side of TSVM of the solutions. The accuracy in fixing TSVM is ± 0.2 °C. The shifts in TSVM of water due to the addition of MgCl₂ and CaCl₂, (ΔT_obs), are found to be positive at low concentrations becoming maxima around the weight fraction w ≃ 2.3 × 10^− 2 for MgCl₂ and w ≃ 3.8 × 10^− 2 for CaCl₂ and becoming negative around w ≃ 5.6 × 10^− 2 for MgCl₂ and w ≃ 3.8 × 10^− 2 for CaCl₂. (ΔT_obs) for MgCl₂ > CaCl₂ > SrCl₂ > BaCl₂ indicating that the strength of the structural interactions in modifying the hydrogen-bonded structure of water is in the order Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺. The results are explained in the light of the structural properties of the anions and cations in the solutions in modifying the three dimensional hydrogen-bonded structure of water.     

Organic light sources look forward to optimize the photosynthesis process

We introduce a series of organic LEDs that exploit the monomer and excimer emissions from single phosphor dopant emitters. These organic LEDs were found to be effective in the simultaneous creation of blue and red emission bands essential for plant growth. By varying the concentration of novel phosphorescent dopants selected from a series of newly synthesized platinum complexes [PtL^22–25Cl], we have manufactured the blue-biased LEDs [with the Commission Internationale de L’Eclairage (CIE) coordinates (x, y) (0.27, 0.37)] and the red-biased LEDs [CIE coordinates (0.53, 0.38)], at a high luminance of ≈500 cd/m² and with external electroluminescence (EL) quantum efficiency of 15–18% photon/electron (→ power efficiency 8–12 lm/W). The EL spectrum most suitable for the action spectrum of photosynthesis yield was that of a device incorporating 20 wt.% content of [PtL²³Cl]. This LED yielded photosynthetic photon flux (PPF) approaching 10 μmol s⁻¹ W⁻¹ of the electrical power, a value which significantly exceeds that for the professional lamps used commonly for horticultural lighting.     

Mechanistic proposal for the electrochemical and sonoelectrochemical oxidation of thiram on a boron-doped diamond anode

A comparative study was carried out of sonochemical (SCh), electrochemical (ECh) and sonoelectrochemical (SECh) strategies for the degradation of the fungicide thiram in dilute aqueous solution. The SCh and SECh studies were performed using a sonicator equipped with an 11 mm titanium-alloy probe and operated at 20 kHz with a power intensity of 523 W cm⁻². In the ECh and SECh investigations, galvanostatic electrolyses were implemented using a single compartment electrochemical cell with a boron-doped diamond electrode as anode and applied current densities in the range 10–50 mA cm⁻². For these processes, the decrease in concentration of thiram was monitored by high performance liquid chromatographic (HPLC) analysis and values of current efficiency and energy consumption were determined. The results showed that the rate of degradation of thiram and the amount of energy consumed were directly proportional to the applied current density, while current efficiency was inversely related to current density. The kinetics of thiram degradation followed a pseudo first order model with apparent rate constants in the region of 10⁻³ min⁻¹. Thiram in aqueous solution was subjected to “exhaustive” degradation by ECh and SECh processes for 5 h at applied current densities of 35 mA cm⁻² and the intermediates/byproducts so-formed were identified by HPLC–mass spectrometry. Mechanisms of the degradation reactions have been proposed on the basis of the results obtained.     

Catalytic dechlorination of 2,4-dichlorophenol by Ni/Fe nanoparticles prepared in the presence of ultrasonic irradiation

In this study, nickle/iron (Ni/Fe) nanoparticles were synthesized by liquid phase reductive method in the presence of 20 kHz ultrasonic irradiation to improve nanoparticles’ disparity and avoid agglomeration. The characterized results showed that this method has obviously modified most of the particles in term of sizes and specific surface areas. Meanwhile, the improved nanoscale Ni/Fe particles were employed for the reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) as a function of some influential factors (Ni content, Ni/Fe nanoparticles dosage, reaction temperature and initial pH values) and degradation path. Experimental results showed that 2,4-DCP was first adsorbed by Ni/Fe nanoparticles, then quickly reduced to o-chlorophenol (o-CP), p-chlorophenol (p-CP), and finally to phenol (P). The application of ultrasonic irradiation for Ni/Fe nanoparticles synthesis was found to significantly enhance the removal efficiency of 2,4-DCP. Consequently, the phenol production rates increased from 68% (in the absence of ultrasonic irradiation) to 87% (in the presence of ultrasonic irradiation) within 180 min. Nearly 96% of 2,4-DCP was removed after 300 min reaction with these optimized conditions: Ni content over Fe⁰ 3 wt%, initial 2,4-DCP concentration 20 mg L⁻¹, Ni/Fe dosage 3 g L⁻¹, initial pH value 3.0, and reaction temperature 25 °C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0737 min⁻¹. This study suggested that the presence of ultrasonic irradiation in the synthesis of nanoscale Ni/Fe particles could be a promising technique to enhance nanoparticle’s disparity and avoid agglomeration.