Ultrasound-assisted Adsorption Research Articles

Ultrasound-assisted enhanced adsorption of textile dyes with metal organic frameworks

In this study, ZIF-67 based metal–organic framework (MOF) is used for the adsorption of several synthetic dye effluents (Malachite green (MG), Rhodamine-B (Rh-B), Methylene Blue (MB) and Congo Red (CR)) with intensified adsorption in the presence of ultrasound. The adsorption capacity of ZIF-67 is evaluated for multiple single dye systems and binary dye mixtures. The effect of different operational parameters such as contact time, adsorbent dosage, dye concentration, temperature, pH, binary dye systems, real effluents, and the presence of ultrasound is explored in detail. The adsorption for single dye systems shows the removal efficiencies in the order of MG > CR > Rh-B > MB. The adsorption of CR and MG on ZIF-67 followed Langmuir isotherm which estimated the maximum adsorption capacity of 701 and 3623 mg. g−1 respectively. An optimum adsorbent loading of 1 g.L−1 is effective for the efficient removal of MG and CR. Further, thermodynamic studies indicate that the adsorption process is spontaneous and endothermic. The kinetic models for both dyes suggested a prevailing chemisorption mechanism, in line with the pseudo second-order model (PSOM). For binary dye systems of MG and CR, the selectivity towards maximum adsorption capacity is favored with MG compared to CR. Ultrasound-assisted adsorption intensified the removal efficiency up to ∼ 67 % and ∼ 93 % within 5 min for CR and MG respectively. ZIF-67 is stable over multiple consecutive cycles affirming its reliability for reuse. Maximum removal of dyes was also obtained with real textile dye effluents.

Ultrasound-assisted adsorption of organic dyes in real water samples using zirconium (IV)-based metal-organic frameworks UiO-66-NH2 as an adsorbent

The utilization of dye adsorption through metal-organic frameworks represents an eco-friendly and highly effective approach in real water treatment. Here, ultrasound assisted adsorption approach was employed for the remediation of three dyes including methylene blue (MB), malachite green (MG), and congo red (CR) from real water samples using zirconium(IV)-based adsorbent (UiO-66-NH2). The adsorbent was characterized for structural, elemental, thermal and morphological features through XRD, XPS, FTIR, thermogravimetric analysis, SEM, BET , and Raman spectroscopy. The adsorption capacity of adsorbent to uptake the pollutants in aqueous solutions was investigated under different experimental conditions such as amount of UiO-66-NH2 at various contact durations, temperatures, pH levels, and initial dye loading amounts. The maximum removal of dyes under optimal conditions was found to be 938, 587, and 623 mg g−1 towardMB, MG, and CR, respectively. The adsorption of the studied dyes on the adsorbent surface was found to be a monolayer and endothermic process. The probable mechanism for the adsorption was chemisorption and follows pseudo-second-order kinetics. From the findings of regeneration studies, it was deduced that the adsorbent can be effectively used for three consecutive cycles without any momentous loss in its adsorption efficacy. Furthermore, UiO-66-NH2 with ultrasound-assisted adsorption might help to safeguard the environment and to develop new strategies for sustainability of natural resources.

Ultrasound-enhanced adsorption of amino acids from aqueous solution onto macroporous resins for green separation: Mass transfer mechanism and acoustic cavitation properties

The utilization of green technology for the recovery of renewable components has garnered significant attention. In this study, efficient and rapid separation of amino acids from aqueous solutions was achieved through ultrasound-assisted macroporous resin adsorption. The numerical simulation revealed the underlying mechanism of mass transfer during ultrasound-assisted adsorption and clarified the impact of acoustic properties on the adsorption process. Low-frequency (LFUS, 20 kHz) caused the damage of resin structure and the increase of adsorption capacity whereas these were less influenced by high-frequency ultrasound (HFUS, 1056 kHz). The external mass transfer coefficient was increased by 161% and 45% during LFUS- and HFUS-assisted adsorption than agitation-assisted adsorption. In addition, both US modes contributed to an enhancement of surface diffusion coefficient by over 100%. The predominant factor governing the intraparticle diffusion for amino acid adsorption was found to be pore volume diffusion, accounting for more than 70% of the overall process. Both LFUS and HFUS were observed to augment the influence of surface diffusion within the overarching diffusion phenomenon, aligning with the concurrent elevation of the surface diffusion coefficient. Furthermore, the mechanism of ultrasound-assisted adsorption was illustrated from the aspect of physical and sonochemical effects generated by the acoustic cavitation. The accumulated acoustic pressure of LFUS exceeded that of HFUS by a factor of 105, reflecting its strong physical effects. The connection between the mass transfer behaviour and acoustic bubble properties during ultrasound-assisted adsorption can provide guidance for the industry to apply ultrasound as a green technology to separate and recover renewable biomaterials from wastewater.

Synergistic sono-adsorption and adsorption-enhanced sonochemical degradation of dyes in water by additive manufactured PVDF-based materials

The present study proposes the first mechanistic model accounting for the most meaningful physico-chemical phenomena taking place in liquid phase adsorption processes under ultrasound. Initially, this study was aimed at developing an easy-to-make and easy-to-recover piezocatalyst for the degradation of RhB in water by combining the high piezocatalytical performance of BaTiO3 with a compatible piezoelectric support such as PVDF, manufactured by a customised additive manufacturing – direct ink writing system with in-situ poling. However, initial results showed that the resulting PVDF-BaTiO3 composite slabs performed worse than BaTiO3 piezocatalysts on their own, and that poling did not have any effect on their performance (82% RhB removal after 2 h when using either poled or unpoled PVDF-BaTiO3 composite slabs compared to 92% RhB removal after 2 h in presence of BaTiO3 piezocatalysts). Further investigation with pure PVDF materials demonstrated that, instead of piezocatalysis, synergistic ultrasound-assisted adsorption and sonochemical degradation were taking place, enabling the removal of >95% of the dye within 40 min of ultrasound treatment in the presence of 4 g L–1 of additive manufactured PVDF slabs. The results of this study and their evaluation with the mechanistic model proposed for liquid phase adsorption under ultrasound suggest that the adsorption of RhB on additive manufactured PVDF slabs was enhanced by the structure, higher specific surface ratio and higher volume of mesopores achieved through the 3D-printing process, as well as the minimisation of film resistance to mass transport due to ultrasound. Moreover, adsorption on additive manufactured PVDF enhanced the sonochemical degradation of the dye due to its high concentration in the adsorbed phase. This study demonstrates that adsorption processes, especially in the presence of PVDF materials, may be significantly more important in piezocatalysis than what has been reported to date, to the point that the synergistic combination of sono-adsorption and sonochemical degradation in presence of additive-manufactured PVDF slabs may be enough to achieve high removal rates of dyes in water.

Ultrasound-assisted adsorption approach for desulfurization of n-heptane using nitrogen-doped magnetic carbon dot nanocomposite

Desulfurization is an important process that not only affects the quality and performances of fuels but also is of great importance from environmental aspects. In this research, nitrogen-doped magnetic carbon dots nanocomposite was synthesized and characterized, and it's potential in adsorptive removal of thiophenes (i.e., thiophene, benzothiophene, and dibenzothiophene) from n-heptane (i.e., as model fuel) was investigated. After optimization of adsorption process, the removal efficiency was obtained above 95% for all of studied thiophenes. Besides that, it was concluded that using ultrasound during the adsorption process could enhance the maximum adsorption capacity. Langmuir model was able to appropriately describe the adsorption isotherm data, where the maximum equilibrium adsorption capacities for thiophene, benzothiophene and dibenzothiophene were obtained as 90.22, 96.51 and 100.38 mgg−1, respectively. The analysis of kinetic data also revealed that all thiophenes were being adsorbed following Pseudo-second-order model. To regenerate the adsorbent, the desorption process was also investigated using different solvents under different conditions, methanol was found as effective solvent for regeneration. The proposed adsorbent was used successfully for the removal of pollutants in a gasoline sample.

Optimization of Methylene Blue Ultrasound-Assisted Adsorption onto Magnetic Sugarcane Bagasse Activated Carbon Using Response Surface Methodology

This study focused on the optimization of methylene blue removal on a magnetic activated carbon from the carbon-rich agro-industrial residue, sugarcane bagasse, synthesized by microwave method. The adsorption process was assisted by ultrasound. The magnetic sugarcane bagasse activated carbon (MSB) was characterized by FTIR and SEM-EDX. Based on FTIR results, the functional groups found in magnetic sugarcane bagasse activated carbon are O-H, C=C, C-O, and Fe-O. The SEM results show that MSB is porous with a rough surface. In addition, EDX data found the presence of three main elements, namely C, O, and Fe. Response Surface Methodology (RSM) Box-Behnken Design was applied to analyze the effects of three parameters, including adsorbent dosage (50-100 mg/L), ultrasonic power (100-200 W), and contact time (30-60 min). The obtained optimum conditions of the adsorption process were the sonication power of 155.65 W, the adsorbent dosage of 89.77 mg/L, and the sonication time of 57,81 minutes. The results indicated that the parameters of adsorbent dosage, ultrasonic power, and contact time influenced the response (qe and methylene blue removal).

Ultrasound-Assisted Adsorption of Perchlorate Using Calcined Hydrotalcites and the Thermal Stabilization Effect of Recycled Adsorbents on Poly(vinyl chloride).

Due to their high anion exchange and memory effect, the layered double hydroxides (LHDs) have wide applications for some areas. In this work, an efficient and green recycling route for layered double hydroxide based adsorbents is proposed specifically for application as a poly(vinyl chloride) (PVC) heat stabilizer without requiring secondary calcination. Conventional magnesium-aluminum hydrotalcite was synthesized using the hydrothermal method followed by removal of carbonate anion (CO32-) between LDH layers by calcination. The adsorption of perchlorate anion (ClO4-) by the memory effect of calcined LDHs with and without ultrasound assistance was compared. Using ultrasound assistance, the maximum adsorption capacity of the adsorbents (291.89 mg/g) was increased, and the adsorption process was fitted using the kinetic Elovich rate equation (R2 = 0.992) and Langmuir adsorption model (R2 = 0.996). This material was characterized using XRD, FT-IR, EDS, and TGA which demonstrated that ClO4- was intercalated into the hydrotalcite layer successfully. The recycled adsorbents were used to augment a commercial calcium-zinc-based PVC stabilizer package applied in a epoxidized soybean oil plasticized cast sheet which is based on an emulsion type PVC homopolymer resin. Use of perchlorate intercalated LDH augmentation yielded significant improvement to static heat resistance as indicated by the degree of discoloration with a life extension of approximately 60 min. The improved stability was corroborated by evaluation of HCl gas evolved during thermal degradation using conductivity change curves and the Congo red test.

Ultrasound-assisted adsorption of chlorpyrifos from aqueous solutions using magnetic chitosan/graphene quantum dot‑iron oxide nanocomposite hydrogel beads in batch adsorption column and fixed bed

Chlorpyrifos is a hazardous material that pollutes the environment and also poses risks to human health. Thus, it is necessary to remove chlorpyrifos from aqueous media. In this study, chitosan-based hydrogel beads with different content of iron oxide-graphene quantum dots were synthesized and used for the ultrasonic-assisted removal of chlorpyrifos from wastewater. The results of batch adsorption experiments showed that among the hydrogel beads-based nanocomposites, the chitosan/graphene quantum dot‑iron oxide (10) indicated a higher adsorption efficiency of about 99.997 % at optimum conditions of the response surface method. Fitting the experimental equilibrium data to different models shows that the adsorption of chlorpyrifos is well described by the Jossens, Avrami, and double exponential models. Furthermore, for the first time, the study of the ultrasonic effect on the removal performance of chlorpyrifos showed that the ultrasonic-assisted removal of chlorpyrifos significantly reduces the equilibration time. It is expected that the ultrasonic-assisted removal strategy can be a new method to develop highly efficient adsorbents for rapid removal of pollutants in wastewater. Also, the results of the fixed bed adsorption column showed that the breakthrough time and exhausting time of chitosan/graphene quantum dot‑iron oxide (10) were equal to 485 and 1099 min, respectively. And finally, the adsorption-desorption study showed the successful reuse of adsorbent for chlorpyrifos adsorption in seven runs without a significant decrease in adsorption efficiency. Therefore, it can be said that the adsorbent has a high economic and functional potential for industrial applications.

Analytical modeling and interpretation of ultrasound-assisted adsorption mechanism of fuchsine dye on MgZnFeO nanocomposites

An efficient co-precipitation followed by ultrasonication process is used for the synthesis of trimetallic MgZnFeO nanocomposites (MZFONCs) and further characterized by FE-SEM, FT-IR, XRD, EDX, etc. spectroscopic techniques. The adsorption process is applied for the removal of toxic cationic Basic Fuchsine (BF) dye using batch experiments. To enhance removal efficiency, the effect of deviation in parameters including shaking time; adsorbent dose; pH; etc. are studied. Q max obtained by Langmuir is found to be 250 mg/g for BF on the MZFONCs surface, at pH = 6.5; 40 min of agitation time, and a small dose of nanoparticles. The best match for the adsorption of BF on MZFONCs is a double-layer method which also describes the adsorption mechanism. The ‘n’ parameter value (0.507–0.628) is obtained from the statistical physics model, which shows mixed-orientation type adsorption of BF molecules on MZFONCs adsorbents. The calculated energies for BF dye adsorption are found to be less than 30 KJ/mol, hence implying an endothermic and physical adsorption mechanism.

Removal of methylene blue from water by ultrasound-assisted adsorption using low-cost bentonites

This study focused on the comparison of ultrasound-assisted (UA) and conventional (shaking or stirring) adsorption techniques, taking into account the time-dependent adsorption capacities. Six different bentonite samples were used as adsorbents, and methylene blue (MB) was used as adsorbate. Effects of pH, contact time, MB initial concentration, and temperature on the UA-adsorption were also investigated. XRD analyzes showed that all the bentonite samples were mostly composed of montmorillonite clay minerals, while XRF analyzes showed that the samples contained high percentage of silicon and aluminum oxides (≥70 wt%). Maximum zeta potential values (37.1–42.1 mV) were measured at pH 12 and, to confirm this, maximum adsorption capacities were also determined at this point. Ultrasound irradiation significantly increased the adsorption capacities of all bentonite samples in the early stages. For example, the adsorption capacity of the B-1 bentonite sample was measured as 388 mg/g by UA-adsorption at the first 5th minute, while it was 286 mg/g by conventional (C) adsorption technique at the same time. All bentonite samples showed increasing adsorption capacity with increased temperature confirming endothermic reaction. Maximum adsorption capacities of B-1, B-2, B-3, B-4, B-5, and B-6 bentonite samples with the 96–100 % MB removal percentages at selected conditions (pH: 11–12, temperature: 25 °C, contact time: 60 min, and MB initial concentrations for B-1: 800, B-2: 700, B-3,4: 650, B-5: 600, and B-6: 500 mg/L) were measured as 398, 342, 320, 296, 288, and 243 mg/g, respectively. Pseudo-second-order kinetic model and Langmuir isotherm model with higher correlation coefficients were found to be more suitable to explain the adsorption of MB cations onto bentonites. In addition, maximum adsorption capacities of B-1, B-2, B-3, B-4, B-5, and B-6 samples at 25 °C calculated from Langmuir isotherm data determined as 500, 454.5, 400, 384.6, 370, and 357.1 mg/g, respectively.

Ligustrum lucidum Leaf Extract-Assisted Green Synthesis of Silver Nanoparticles and Nano-Adsorbents Having Potential in Ultrasound-Assisted Adsorptive Removal of Methylene Blue Dye from Wastewater and Antimicrobial Activity.

Present study was conducted to investigate the adsorption and ultrasound-assisted adsorption potential of silver nanoparticles (AgNPs) and silver nanoparticles loaded on chitosan (AgCS composite) as nano-adsorbents for methylene blue (MB) removal. AgNPs were synthesized using leaf extract of Ligustrum lucidum, which were incorporated on the chitosan’s surface for modification. UV–Vis Spectroscopy, FTIR, XRD, SEM, and EDX techniques were used to confirm the synthesis and characterization of nanomaterials. Batch adsorption and sono-adsorption experiments for the removal of MB were executed under optimal conditions; for fitting the experimental equilibrium data, Langmuir and Freundlich’s isotherm models were adopted. In addition, the antimicrobial potential of the AgNPs and AgCS were examined against selected bacterial and fungal strains. UV–Vis spectroscopy confirmed AgNPs synthesis from the leaf extract of L. lucidum used as a reducer, which was spherical as exposed in the SEM analysis. The FTIR spectrum illustrated phytochemicals in the leaf extract of L. lucidum functioning as stabilizing agents around AgNPs and AgCS. Whereas, corresponding crystalline peaks of nanomaterial, including a signal peak at 3 keV indicating the presence of silver, were confirmed by XRD and EDX. The Langmuir model was chosen as an efficient model for adsorption and sono-adsorption, which exposed that under optimum conditions (pH = 6, dye initial concentration = 5 mg L−1, adsorbents dosage = 0.005 g, time = 120 min, US power 80 W), MB removal efficiency of AgNPs was >70%, using ultrasound-assisted adsorption compared to the non-sonicated adsorption. Furthermore, AgNPs exhibited promising antibacterial potential against Staphylococcus aureus with the maximum zone of inhibition (14.67 ± 0.47 mm). It was concluded that the green synthesis approach for the large-scale production of metallic nanoparticles is quite effective and can be recommended for efficient and cost-effective way to eradicate dyes, particularly from textile wastewater.

Bridge between mass transfer behavior and properties of bubbles under two-stage ultrasound-assisted physisorption of polyphenols using macroporous resin

Ultrasound is efficient to enhance various mass transfer processes. This study demonstrates that both ultrasound pretreatment and ultrasonication during adsorption promote the physisorption of polyphenols. The time to reach the adsorption equilibrium was shortened by more than 90 % when the resin diameter deceased from 592 μm to 60.23 μm in the intensive ultrasound pretreatment. The mass transfer mechanism of adsorption under mild sonication differs from that of adoption with intensive ultrasound pretreatment. Mild sonication during adsorption strengthens the influence of surface diffusion of polyphenols on intraparticle diffusion. In contrast, severe disruption of resin particles due to intensive ultrasound pretreatment weakens the surface diffusivity of polyphenols and reduces the contribution of surface diffusion. Also, the physics and sonochemistry of cavitation under sonication environments were explored. Under intensive and mild ultrasound treatments, the calculated bubble numbers were approximately 18789 L-1 and 6312 L-1, respectively. Moreover, a relationship was established between adsorption capacity from mass transfer modeling and bubble properties including the bubble collapse pressure, bubble number, processing time, and processing scale. This bridge between mass transfer behavior and properties of bubbles provides guidance and new insight for the design and scale-up of the ultrasound-assisted adsorption.

Two agitation routes for the adsorption of Reactive Red 120 dye on NiFe LDH/AC nanosheets from wastewater and river water

The influence of the ultrasound-assisted and conventional adsorption processes as two commonly used agitation techniques on the adsorptive removal of Reactive Red 120 dye onto Nickel Iron Layered Double Hydroxides/Activated Carbon (NiFe LDH/AC) nanosheets from wastewater and river water were studied. The impact of key adsorption parameters such as solution pH (2−10), mass of the adsorbent (10–50 mg), solution volume (20–80 mL) and contact time (5–50 min) were explored by the ultrasound-assisted and conventional adsorption processes, under similar conditions. The results of the adsorption isotherms and kinetics demonstrated that the experimental data fitted well with the Redlich-Peterson and the pseudo-second order kinetic models, respectively, for both adsorption processes. Under optimum conditions, the maximum adsorption capacities were determined as 118.20 and 99.60 mg g−1 for the ultrasound-assisted and conventional adsorption of RR 120 dye, respectively. Notably, the chemisorption adsorption mechanism was influenced by different interactions such as electrostatic attraction, n-π stacking, and H-bonding. Interestingly, physicochemical parameters, such as pH, Electrical Conductivity (EC), Total dissolved solids (TDS), and turbidity after the application of NiFe LDH/AC for the adsorption of RR 120 dye in wastewater and river water samples were comparable to the drinking water parameters, thus exhibiting that the ultrasound-assisted adsorption was better suited for the removal of RR 120 dye.

Ultrasound-assisted adsorption of Pb ions by carbonized/activated date stones from singles/mixed aqueous solutions

This work aims to assess the adsorption efficiency of date stones biowaste subjected to carbonization and activation processes for the removal of Pb ions from single and mixed solutions. Several techniques have been used for characterization of adsorbents such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), methylene blue index and point of zero charge (pHpzc). An excellent adsorption capacity of 97.43% is achieved at an initial concentration of 300 ​mg/L, solution volume 75 ​mL of Pb nitrate, adsorbent mass of 0.7 ​g, temperature of 30 ​°C, a stirring speed of 500 ​rpm/min, a contact time of 180 ​min and pH 6. Specifically, a comparison has been conducted between carbonized/activated date stones “CADS” and commercial activated carbon “CAC” besides investigating the influence of the presence of Co ions and the utilization of ultrasound radiation. A higher adsorption rate of 98.16% is reached under ultrasound radiation at Pb(II) initial concentration of 100 ​mg/L for a contact time of 3 ​h. Nevertheless, the temperature has shown a negative effect; the adsorption rate decreases from 98.31% at 18 ​°C to 92.70% at 60 ​°C. The modeling of the experimental adsorption data manifests a type-L isotherm characteristic of Langmuir and Freundlich models. The kinetic study has shown that the experimental data are well described by a pseudo-second-order rate model and controlled by the internal diffusion, a limiting-step that controls the transfer rate of Pb(II) to the adsorbent surface. The calculated thermodynamic parameters (ΔG0, ΔH0, ΔS0) indicate that the adsorption of Pb(II) is spontaneous and exothermic process.

Ultrasound-assisted adsorption of dyes and cadmium ion from aqueous solutions by ZnAl2O4 nanoparticles

In this study, we investigated the process of removing heavy metal ions and dyes by ZnAl2O4 nanoparticles from an aqueous solution. ZnAl2O4 nanoparticles were characterized by various physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Brauer–Emmett–teller (BET). The parameters of solution pH, sonication time, adsorbent amount, Cd2+, AO, and MB concentrations were investigated under different conditions. We performed the process modeling by Box-Behnken design (BBD) based on response surface methodology (RSM). A second-order polynomial equation was proposed to remove the desired analytes. The high values of the R2adj> 98% and R2pred> 97% parameters indicated the accuracy of second-order polynomial equations for all three analytes. In optimal conditions (pH = 6 for Cd2+, pH = 7 for AO and MB dyes, Cd2+ concentration 20 mg L−1, adsorbent amount 55 mg, ultrasound time 17 min, concentration of AO and MB dyes 10 mg L−1) 92.78%, 97.73%, and 95.30% were removed from Cd2+, AO and MB, respectively. Interference studies showed that the presence of different ions did not considerably affect the removal of Cd2+, AO, and MB. Reusability studies were analyzed based on the number of adsorption-desorption cycles, and the results showed no significant reduction in ZnAl2O4 efficiency if ZnAl2O4 is reused up to 5 times. ZnAl2O4 nanoparticles were also used to remove Cd2+, AO, and MB from environmental and wastewater samples. The results showed that the above process could be used with appropriate and high efficiency to remove Cd2+, AO, and MB from environmental water samples.

Ultrasound-assisted adsorption of fenoterol from water solution by shells of plum seeds activated carbon

• AC obtained by of plum seeds using water vapor is suitable for use in human medicine. • The PSC has a high adsorption capacity for fenoterol, and it is 337.8 mg/g. • The process of adsorption of fenoterol on PSC is thermodynamically favorable. • The application of ultrasound has a favorable of adsorption of fenoterol on PSC. The aim of the study was to preliminarily investigate the possibility of using active carbon (AC) of the shell of plum seeds (PSC) in cases of acute poisoning by excessive oral intake of fenoterol. It was found that the PSC surface is characterized by a large specific area, 1680 m 2 /g, high Langmuir monolayer capacity, 337.8 mg/g without ultrasound (US) and 351 mg/g with US. The Langmuir, Flory–Huggins, pseudo second order and intraparticular diffusion model, follow the experimental results well, R 2 = 0.99 was in all cases. According to Boyd’s criterion, a combination of diffusion of solute through the film and through the pores, limiting steps for fenoterol adsorption onto PSC are. The contribution of US was positive in this study. This was shown by the adsorption rate constant of the pseudo-second-order which, without application of US it was 298 g/mg·min and with the application of US was 347 g/mg·min. The Gibbs free energy ΔG values, −27.25 kJ/mol, −27.93 kJ/mol and −28.58 kJ/mol, obtained by Langmuir constant K L , were negative at all operating temperatures, verifying that the adsorption of fenoterol was spontaneous and thermodynamically favorable. PSC has been shown to be a highly effective adsorbent that can be used in acute oral fenoterol poisoning and US is not contraindicated, on the contrary.

Removal of hexavalent chromium ions and Acid Red 18 by superparamagnetic CoFe2O4/polyaniline nanocomposites under external ultrasonic fields

In the present research, the adsorptive removal of dye and Cr(VI) ions from the aquatic solutions have been investigated using fabricated magnetic cobalt ferrite (CoFe 2 O 4 ) nanoparticles coated by polyaniline (CoFe 2 O 4 /PANI) via a hydrothermal and in-situ polymerization method. Magnetic composite of CoFe 2 O 4 /PANI was characterized by FE-SEM, EDS, XRD, VSM, FTIR, BET, BJH, and element mapping. The resulting composite was applied for the removal of hexavalent chromium (Cr(VI)) ions and Acid Red 18 (AR18) anionic azo dye individually from an aqueous solution under external ultrasonic fields. The removal efficiency of Cr(VI) ions and AR18 dye were studied as functions of the various parameters like time sonication, amount of adsorbent, initial concentration of Cr(VI) or AR18, and solution pH. The adsorption behavior and the equilibrium data were represented by the Langmuir isotherm model. The maximum monolayer adsorption capacity by as-prepared composite reached 103.11 mg g −1 and 172.41 mg g −1 for Cr(VI) ions and AR18 dye, respectively. The thermodynamic analysis demonstrated that these adsorption processes were spontaneous in nature and endothermic. The magnetically recyclable composite indicated suitable reusability during cyclic adsorption. The increase in ionic strength causes a decrease in the adsorption of Cr(VI) and AR18. This study may provide a promising magnetic composite for the efficient removal of inorganic and organic anions from the water environment. • Application of magnetic CoFe 2 O 4 /PANI for ultrasound assisted adsorption of Cr(VI) ions and AR18 dye. • Desirability function approach combined with CCD method was used to optimize the process variables. • CoFe 2 O 4 /PANI is superior to CoFe 2 O 4 for Cr(VI) ions and AR18 dye adsorption. • The maximum adsorption capacity for Cr(VI) ions and AR18 dye reached 103.11 mg g −1 and 172.41 mg g −1 , respectively. • Reusability tests indicated suitable regenerability of CoFe 2 O 4 /PANI.

Ultrasound-assisted adsorption/desorption of jujube peel flavonoids using macroporous resins

The work explored the process of ultrasound-assisted adsorption/desorption to efficiently purify jujube peel flavonoids (JPFs) using macroporous resins (MRs). The impact of ultrasound power and temperature on the adsorption/desorption features of JPFs on MRs were studied. The maximum adsorption (80.21 ± 2.11 mg/g) /desorption (76.22 ± 1.68 mg/g) capacity of total flavonoids content were obtained. The pseudo-second-order kinetic and Freundlich isotherm models better described the whole process of ultrasound-assisted adsorption. The adsorption process was spontaneous, physical, and dominated by multilinear intraparticle diffusion. Ultrasound mainly enhanced the adsorption capacity by strengthening the formation of hydrogen bonds and increasing the surface roughness of MRs. Besides, the principal individual flavonoid ((+)-Catechin, (−)-Epicatechin, Rutin, Quercetin-3-O-robinobioside) content of JPFs in ultrasound treatment was 2–3 times that of shaking treatment, and biological activities were significantly increased. Overall, as a low-cost green technology, ultrasound can improve the properties of MRs and better purify JPFs.

The superior adsorption capacity of 2,4-Dinitrophenol under ultrasound-assisted magnetic adsorption system: Modeling and process optimization by central composite design

2,4-Dinitrophenol (DNP) was listed as a priority pollutant; accordingly, DNP-contaminated effluent must be treated before discharging to the receiving resources. In the present study, the hybrid ultrasound-assisted GO-Fe3O4 system was employed to decontaminate DNP solution. Ultrasound irradiation makes the mass transfer of adsorbate improved and Fe3O4 enables GO separation from liquid phase under external magnetic field. The as-synthesized GO-Fe3O4 composite was characterized by SEM, TEM, XRD, FTIR, BET and VSM. A response surface methodology based central composite design (RSM-CCD) was used to estimate and optimize of various variables on DNP removal percentage. Under optimal conditions (pH: 4.45, adsorbent dose: 0.178 g/L, ultrasound frequency: 40.02 kHz and DNP concentration: 50.10 mg/L, maximum adsorption capacity was calculated to be 425.58 mg/g for the ultrasound system, higher than the simple system 309.40 mg/g, indicating the importance of synergistic effect between the ultrasound waves and the adsorption process. The ultrasound-assisted adsorption system showed the better agreement with the Langmuir isotherm (R2 > 0.997), while the results of the stirring system were more consistent with the Freundlich model (R2 > 0.991). The experimental results indicated that the pseudo-second-order kinetic model well fitted by experiment data and rate constant was calculated to be 0.000148 min−1 and 0.000002 min−1 under ultrasound and silent systems, respectively. The rate of desorption under ultrasound was more favorable and reuse of the adsorbent in both systems after 10th consecutive cycles reduced by about 22%. Thermodynamic calculations also confirmed the endothermicity and spontaneity of both systems. Electrostatic attraction, hydrogen bonding, and π -π interactions played key roles during the adsorption of DNP onto the MGO. In conclusion, the outcomes of this study provide valuable information of the ultrasound-assisted GO-Fe3O4 system for practical applications.

Ultrasound-assisted Adsorption of Copper from Aqueous Solution by using Natural Mauritanian Clay as Low-cost Adsorbent: A Preliminary Study

The aim of the present study concerns the feasibility of using natural Mauritanian clay for the removal of Copper from an aqueous solution. The proposed adsorbent was characterized by pH, moisture, bulk density, loss mass ignition, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The effects of adsorbent mass and contact time were analyzed. The adsorption kinetic data were analyzed using the Pseudo First Order (PFO) and Pseudo Second Order (PSO) models and the results showed that the PSO model best described the adsorption kinetics. The adsorption equilibrium of Copper was described by Langmuir and Freundlich equations. The equilibrium is perfectly adapted to the Langmuir model with the maximum adsorption capacities for Copper on Mauritanian clay adsorbent at pH 6.8 and pH 9 were found to be 0.081 and 0.31 mg g-1, respectively on a single layer. This study convinced that the Mauritanian clay is a promising adsorbent and could be an alternative, attractive, economic, and environmentally friendly adsorbent for Copper removal from aqueous solution via ultrasound-assisted adsorption.