Ultrasonic-assisted Adsorption Research Articles

Elimination of Ciprofloxacin from Aqueous Solution by Ultrasonic-Assisted Adsorption Using Chitosan Crosslinked Graphene Oxide Nanoparticles

Elimination of Ciprofloxacin from Aqueous Solution by Ultrasonic-Assisted Adsorption Using Chitosan Crosslinked Graphene Oxide Nanoparticles

Ultrasonic-assisted adsorption of heavy copper and lead metal ions by g-C3N4, application of g-C3N4@MNPs (M: Pb, Cu) in the catalytic photoreduction of organic pollutants

In this paper, the prepared g-C3N4 was used firstly as an adsorbent of copper and lead ions by using both ultrasonic and classical methods in order to improve the adsorption of bigger metal amounts in a very good dispersion. This adsorption study was performed in-depth by evaluating the influence of contact time, the metal concentration, and the pH effect. The adsorption mechanism follows the Langmuir isotherm and the pseudo-second-order model which confirm its chemisorption type. The maximal adsorbed quantities obtained were 285.7 mg/g and 238.09 mg/g for Cu2+ and Pb2+ respectively which represent a high performance. Once the adsorption was done, the obtained nanocomposite g-C3N4@CuNPs and g-C3N4@PbNPs were used in the photocatalytic reduction of anionic and cationic dye in a simple and binary system which constitutes a recovery and recycling of heavy metals. All materials were characterized by several analyses in order to investigate the structural, thermal, textural, and morphological properties. Each nanocomposite showed an affinity for a specific material according to its surface charge. Finally, the rate constants towards methylene blue dye reached a high level up to 1.2881 min−1 and 0.6406 min−1 for the g-C3N4@CuNPs and g-C3N4@PbNPs respectively, implying a large efficiency against both organic and inorganic water pollutants.

Ultrasonic-assisted removal of cationic and anionic dyes residues from wastewater using functionalized triptycene-based polymers of intrinsic microporosity (PIMs)

In this work, a series of hypercrosslinked polymers of intrinsic microporosity (HCP-PIMs), namely nitro-triptycene (TRIP-NO2), amino-triptycene (TRIP-NH2), sulfonated-triptycene (TRIP-SO3H) and hydrocarbon-triptycene (TRIP-HC), are employed for the adsorption of organic dyes from wastewater. The materials show the efficient removal of cationic (malachite green, MG) and anionic (methyl orange, MO) dyes. The adsorption parameters herein investigated include the initial pH, the adsorbate concentration and the contact time, with the aim to elucidate their effect on the adsorption process. Furthermore, the adsorption kinetic and isotherms are studied, and the findings suggest the results fit well with pseudo-second-order kinetics and Langmuir model. The reported maximum adsorption capacity is competitive for all the tested polymers. More specifically, TRIP-SO3H and TRIP-HC exhibit adsorptions of ~ 303 and ~ 270 mg g−1 for MG and MO, respectively. The selectivity toward cationic and anionic dyes is assessed by mixing the two dyes, and showing that TRIP-HC completely removes both species, whereas TRIP-NO2, TRIP-NH2 and TRIP-SO3H show an enhanced selectivity toward the cationic MG, compared to the anionic MO. The effect of the type of water is assessed by performing ultrasonic-assisted adsorption experiments, using TRIP-SO3H and TRIP-HC in the presence of either tap or seawater. The presence of competing ions and their concentrations is evaluated by ICP-MS. Our study shows that tap water does not have a detrimental effect on the adsorption of both polymers, whereas, in the presence of seawater, the performance of TRIP-HC toward MO proved to be more stable than MG with TRIP-SO3H, which is probably due to a larger concentration of competing ions. Comparison between ultrasonic-assisted and magnetic stirring adsorption demonstrates that the former exhibits a greater efficiency. This seems due to a more rapid mass transfer, driven by the formation of high velocity micro-jets, acoustic microstreaming and shock waves, at the polymer surface. Reusability studies show a good stability up to five adsorption–desorption cycles.

Isotherm, kinetics, thermodynamics, recyclability and mechanism of ultrasonic assisted adsorption of methylene blue and lead (II) ions using green synthesized nickel oxide nanoparticles

One of the urgent global problems demanding effective mitigation strategies is the pollution caused by organic dyes and metal ions like methylene blue and lead (II) ions. In recent times, the increasing applications of nickel oxide nanoparticles in biomedicine, catalysis, sensors in optoelectronic materials, and the prevention of environmental pollution have attracted researchers' interest across the globe. Herein, Psidium guajava leaves extract was utilized to synthesize green nickel oxide nanoparticles (PG-NiONPs). Surface and analytical techniques were employed to characterize PG-NiONPs and were thereafter applied to remove methylene blue and lead (II) ions from wastewater. The results revealed the quantified presence of phytochemicals such as alkaloids, phenols, tannins, flavonoids and saponins in the Psidium guajava leaves extract. The prepared PG-NiONPs revealed a crystalline phase, functional groups, mesoporous and microstructural arrangements typical of nickel oxide nanoparticles. The surface area of PG-NiONPs was obtained as 85.40 m2/g. The best ultrasonic-assisted adsorption of MB and Pb(II) ions was achieved at pH values of 6 and 5 for MB and Pb(II), a contact time of 60 min, an adsorbent mass of 40 mg/L, and a temperature of 50 °C, respectively. The maximum MB and Pb(II) adsorption capacities of 495.58 and 508.56 mg/g were evaluated. The experimental data corroborated with the pseudo-second-order and Toth isotherm models. The adsorption of MB and Pb(II) over green PG-NiONPs was a thermodynamically spontaneous process. The PG-NiONPs indicated good recyclability with high stability even after 8 adsorption cycles. Overall, the PG-NiONPs is a potential adsorbent for improved toxic dyes, metal ions and other scavengers removal from wastewater.

Erratum to: Comparison of Conventional and Ultrasonic-Assisted Adsorption Processes by Using H3PO4 Activated Cypress Tree Cone for Methylene Blue Removal

Erratum to: Comparison of Conventional and Ultrasonic-Assisted Adsorption Processes by Using H3PO4 Activated Cypress Tree Cone for Methylene Blue Removal

Comparison of H3PO4 and ZnCl2 Activated Filtered Coffee Waste Carbon-Based Adsorbents in Methylene Blue Removal by Using Ultrasonic-Assisted Adsorption

Comparison of H3PO4 and ZnCl2 Activated Filtered Coffee Waste Carbon-Based Adsorbents in Methylene Blue Removal by Using Ultrasonic-Assisted Adsorption

Comparison of Conventional and Ultrasonic-Assisted Adsorption Processes by Using H3PO4 Activated Cypress Tree Cone for Methylene Blue Removal

Comparison of Conventional and Ultrasonic-Assisted Adsorption Processes by Using H3PO4 Activated Cypress Tree Cone for Methylene Blue Removal

Ultrasonic-Assisted Removal of Eriochrome Black T onto Vermicompost: Characterization, Isotherm and Kinetic Modelling

Recently, utilization of biological adsorbents plays an important role in the removal of toxic dyes such as Eriochrome Black T (EBT) azo-dye as they are considered as being produced from natural renewable source, easy availability, low cost, and being environmentally friendly. In this study, vermicompost (VC) was utilized to remove Eriochrome Black T (EBT) azo-dye from aqueous solution along ultrasonic ultrasonic-assisted adsorption. The parameters such as pH, adsorbent amount, operating time, and initial EBT concentration were investigated. The highest adsorption capacity was obtained as 50.64 (mg-EBT g-1-VC) at the pH of value of 2 after 2 minutes of ultrasonic adsorption. Pseudo first order kinetic model fitted very well with the experimental data (R2=0.9824). The determination coefficient of Temkin isotherm model (R2=0.8659) revealed that suggested model was compatible to experimental results. The results suggested that ultrasonic assisted adsorption of EBT onto VC could be cost- and time-efficient. Besides, the Scanning Electron Microscopy (SEM) analysis of adsorbent identified the surface structure morphology of VC. Moreover, functional groups of VC were detected after and before the ultrasonic-assisted adsorption by using Fourier Transform Infrared Spectroscopy (FTIR). Thus, interaction mechanism between VC and EBT were determined.

Ultrasonic-assisted adsorption of eriochrome black T and celestine blue dyes onto Ipomoea batatas-derived biochar

ABSTRACT In a bid to develop efficient biochars, we prepared new biochar by the pyrolysis of Ipomoea batatas feedstock for the ultrasonic-aided adsorption of eriochrome black T (EBT) and celestine blue (CB) dyes. The characterisation of the Ipomoea batatas-derived biochar (IBBC) showed potent functional groups, good thermal stability, porous structure and a point of zero charge of 6.41. The pH of 2.0 and 7.0 was found to be optimum for the uptake of anionic EBT and cationic CB onto IBBC, respectively. A decrease in the surface area of IBBC from 96.35 m2/g to 48.43 m2/g and 32.11 m2/g was obtained after the adsorption of EBT and CB, respectively. Thermogravimetric analysis revealed high thermal stability of IBBC up to 350°C. The Energy dispersive X-ray (EDX) spectrum revealed carbon (52.6%), oxygen (24.5%) and potassium (7.1%) as the major component of the biochar. The elemental analysis showed carbon, hydrogen and nitrogen compositions of 55.4%. 2.6% and 1.2%, respectively. Moreover, a biochar yield of 36.2% was obtained. The adsorption of both dye molecules was well correlated by the Freundlich isotherm, supported by the Scatchard model analysis. Kinetics was well fitted to the film diffusion and pseudo-second-order models, while thermodynamics showed an endothermic and spontaneous dye uptake on IBBC. The adsorption capacity of the biochar for EBT and CB was 59.24 mg/g and 63.69 mg/g respectively. Percentage desorption of 87.5% for EBT and 82.3% for CB was achieved during regeneration of the dye-loaded biochar. Moreover, IBBC showed good potentials to be reused for adsorption. The results revealed the potentials of the novel biochar for efficient adsorption of both cationic and anionic dye species.

Modeling and optimization of porous aerogel adsorbent for removal of cadmium from crab viscera homogenate using response surface method and artificial neural network

The purpose of this study was to establish an efficient modern strategy for the reduction and control of cadmium (Cd) content in the crab viscera homogenate. To this end, the coupling of an artificial neural network (ANN) technique with the genetic algorithm (GA) method and compared the performance of GA-ANN with response surface methodology (RSM) were demonstrated in the prediction and optimization of the ultrasonic-assisted adsorption of Cd using a aerogel adsorbent. On the basis of single factor test, the data sample was established by Box–Behnken Design, and the effects of ultrasonic time, temperature, the addition amount of aerogel, and pH on the removal rate of Cd were researched. The results revealed that the RSM and GA-ANN models had relative errors and coefficients of determination R2 values of 3.90%, 0.8440, and 1.79%, 0.9283, respectively, suggesting that GA-ANN is more accurate than RSM. The maximum percentage of Cd extracted (79.13%) was obtained using GA-ANN model as ultrasonic time of 87 min, temperature of 81 °C, adsorbent dosage of 0.07 g, pH of 3.20. In conclusion, the present results provide an effective method for optimizing multi-technology coupling to reduce the toxic heavy metal content in aquatic products.

Biosynthesis of copper oxide nanoparticles using biomass, peel, and extract polysaccharides of Solanum Tuberosum for ultrasound‐assisted adsorption of azo direct red 80 contaminants

Bio-fabrication of nanomaterials using plant polysaccharides has recently attracted much scientific attention due to its low cost and simple operation. The green synthesis of copper oxide nanoparticles as adsorbent is performed for the removal of azo direct red 80 contaminants from aqueous solution with adsorption and ultrasonic-assisted adsorption processes. The biomass, peel, and extract polysaccharides of Solanum Tuberosum were applied as eco-friendly stabilizing agents to synthesize nanoparticles. The CuO nanoparticles were characterized using FESEM, XRD, BET, and antibacterial activity tests. The CuO nanoparticles biosynthesized from peel extract have better structural properties as compared to the nanoparticles prepared from biomass and extract of Solanum Tuberosum. The result showed that the average crystallite size of the CuO nanoparticles was about 25 nm with a specific surface area of 16.35 m2/g. The adsorption capacities of 13.09 and 14.07 mg/g were obtained for dye removal with the adsorption and ultrasonic-assisted adsorption processes. Adsorption process followed the pseudo-second-order kinetic model and the contribution of intra-particle diffusion was also observed. The adsorption potential of the nanoparticles in adsorption and ultrasonic-assisted adsorption processes was assessed for binary dye solution with synergetic effect. The CuO nanoparticle has shown its high regeneration ability even after 4 consecutive cycles of regeneration-reuse.

Rapid and efficient ultrasonic assisted adsorption of PNP onto LDH-GO-CNTs: ANFIS, GRNN and RSM modeling, optimization, isotherm, kinetic, and thermodynamic study

In this work, the original, inexpensive, efficient and biodegradable nanocomposite (Mg/Co/Al/LDH − GO − MWCNT) was fabricated and characterized by the analyses of SEM, EDX, TEM, XRD, RAMAN, TGA, and BET and then used as adsorbent for removal of Para Nitrophenol (PNP) from aqueous solutions. In addition, the GRNN, ANFIS and RSM based on the CCD experiments were developed to predication the Para Nitrophenol removal. The aforementioned approaches determined the impacts of adsorbent mass, PNP concentration, pH, temperature, and sonication time. In addition, the preference of mentioned approaches was judged in terms of different statistical criteria including RMSE, MSE, MAE, AAD, SSE, SAE, ARE, HYBRID, MPSD, χ2 and R2 and the best algorithm was proposed for the process studied. Furthermore, comprehensive kinetic, isotherm, thermodynamic, the effect of interfering ions, reusability cycles and optimization (by GA and DF) studies were investigated to understand the behaviour and adsorption mechanism of PNP on the surface of Mg/Co/Al/LDH-GO-MWCNT nanocomposite. The results proposed that the optimum values to attain a maximum PNP removal (94.77%) were Mg/Co/Al/LDH-GO-MWCNT dose 10.00 mg, pH 5.35, temperature 50.15 °C, PNP initial concentration 16.22 mg L−1, and sonication time 13.36 min with DF about 0.94. The equilibrium data pointed out excellent fit to the Langmuir isotherm model with maximum monolayer adsorption capacity of 769.23 mg/g at 25 °C and pH 5.35. Dubinin–Radushkevich isotherm model based on mean sorption energy determine high contribution of chemisorption (9.280 kJ/mol) on removal process. Moreover, diffusion-chemisorption kinetic model delivered a better correlation for the experimental data in comparison to the pseudo-first-order kinetic model and intraparticle diffusion mechanism. High removal efficiency (96%) of PNP in only 13.36 min, along with an excellent capacity (823.33 mg/g) that has ever been reported and reusability (seven times), turns the nanocomposite to a very promising option in adsorption of PNP.

Efficient ultrasonic assisted adsorption of organic pollutants employing bimetallic-carbon nanocomposites

ABSTRACT In recent times, carbon nanofibers (CNF) have been used extensively for the remediation of environment owing to their hollow layered organization, high specific surface area, and strong electrostatic interactions which formulate it as an appropriate adsorbent material. Metallic nanoparticles were blended onto its surface in order to engineer a novel metal-CNF nanocomposite. The study aimed the ultrasonic assisted adsorption of rhodamine B dye (RhB) and pesticide dichlorophenoxyacetic acid (2,4-D) out of aqueous matrix by using silver (Ag) and copper (Cu) based bimetallic composite (Ag-Cu/CNF) material. The synthesized nanocomposites were characterized for its crystalline analysis, textural characteristics, surface chemical bonding, and specific surface area. Ag-Cu/CNF illustrated superior adsorptive efficiency when compared with Ag/CNF and Cu/CNF. Adsorption equilibrium was studied by Freundlich and Langmuir isotherms. Evaluation of the data predicted that Langmuir model described the maximum fit toward equilibrium data with utmost adsorption efficiency of 201 mg/g and 112 mg/g for RhB and 2,4-D, respectively. Also, the comparison between adsorption aided by ultrasound, magnetic stirrer, and vortex shaker assisted methods revealed that sono-sorption is a proficient option for commencement of adsorption phenomenon due to convenient and facile diffusion.

Ultrasonic-assisted adsorption of propyl paraben on ultrasonically synthesized TiO2 nano particles loaded on activated carbon: optimization, kinetic and equilibrium studies

Ultrasonic-assisted adsorption of propyl paraben on ultrasonically synthesized TiO2 nano particles loaded on activated carbon: optimization, kinetic and equilibrium studies

Rice husk ash derived nanocrystalline ZSM-5 for highly efficient removal of a toxic textile dye

Synergistic solution of two different environmental issues such as solid waste management and wastewater treatment is not just a sustainable solution but also adds to circular economy. In this study, a novel nano ZSM-5 zeolite (nZSM-5) was synthesized from agro-waste rice husk ash by two-step method for removal of industrial toxic dye crystal violet (CV) from water using ultrasonic-assisted adsorption process. The physico-chemical properties of as-synthesized nZSM-5 was examined by means of TEM, XRF, FESEM, XRD, FTIR, and BET analysis. Surface area, average pore volume, average crystal size, and product yield of nZSM-5 were found as 608.93 m2/g, 0.245 cm3/g, and 8.5 nm, 87% respectively. Also, from FESEM analysis, the average particle size was found to be 32.42 nm. Effect of solution pH (3–11), sonication time (0–60 min), adsorbent dose (50–250 mg/100 ml), and initial CV dye concentration (25–125 mg/L) on nZSM-5 was analyzed in ultrasound-assisted adsorption process. Pseudo-second order kinetic (R2 = 0.994) model and Langmuir isotherm (R2 = 0.991) model were best fitted for the adsorption of CV on nZSM-5 with maximum Langmuir adsorption capacity of 125.43 mg/g. The removal efficiency of nZSM-5 zeolite for CV dye was estimated as 99.99%. This study suggests that the synthesized novel nZSM-5 zeolite is a highly efficient adsorbent for CV dye under ultrasonication.

Biogenic and chemically synthesized Solanum tuberosum peel\u2013silver nanoparticle hybrid for the ultrasonic aided adsorption of bromophenol blue dye

This work was aimed at the synthesis of a hybrid (STpe-AgNP), obtained by impregnation of silver nanoparticles (AgNP) onto Solanum tuberosum peel (STpe), for the ultrasonic assisted adsorption of bromophenol blue (BB) dye. SEM, FTIR, XRD, EDX, TGA and BET techniques were used to characterize the adsorbents. The XRD, SEM and EDX confirmed successful impregnation of AgNPs onto STpe to form the hybrid. The AgNPs impregnated onto the hybrid were found to be water stable at various pH values of 2.0–9.0. Chi-square (χ2 < 0.024) and linear regression (R2 > 0.996) showed that the Freundlich model was best fitted among the isotherm models, corroborated by the oriented site model. Kinetic analysis conformed to the intraparticle diffusion and pseudo-first-order rate equations, while thermodynamics displayed a physical, spontaneous and endothermic adsorption process. The presence of competing Pb(II), Ni(II), Cd(II) and Zn(II) metal ions in solution interfered with the adsorption of BB onto the biosorbents. In terms of reusability, STpe and STpe-AgNP showed BB desorption of 91.3% and 88.5% respectively, using NaOH as eluent. Ultra-sonication significantly enhanced the adsorption of BB by both adsorbents, but the impregnation of AgNPs only slightly improved adsorption of the dye from the simulated wastewater. This study also illustrated that pristine STpe biomass waste is a cheap viable option for the decontamination of BB from water.

Comparative study on ultrasonic assisted adsorption of Basic Blue 3, Basic Yellow 28 and Acid Red 336 dyes onto hydromagnesite stromatolite: kinetic, isotherm and error analysis

In this study, we focused on the performance of an adsorbent such as a hydromagnesite stromatolite (HS) for rapid and efficient ultrasonic-assisted adsorption of Basic Blue 3, Basic Yellow 28 and Acid Red 336 dyes from aqueous solution. The initial dye concentration (0.05-0.10 g/L), adsorbent dose (0.1–0.5 g), pH (2–10), and temperature (20-40 °C) were evaluated. HS was characterized by means of BET, FTIR, SEM, and XRD. The surface area was observed to be 20.12 m2/g for HS. Different kinetic models, isotherm models (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Redlich-Peterson, Frumkin, Harkins - Jura, Halsey and Henderson) and error analysis were calculated to explain the adsorption mechanism of dye on the surface of HS. The kinetic parameters of adsorption of all dyes were well-defined by the pseudo-second-order with R2 of 0.984-1.000 while the thermodynamic parameters demonstrated endothermic and feasible nature of the adsorption with ΔHo of 24.6-45.1 kJ/mol and ΔSo of 109.4-322.5 J/mol K. The uptake (%) values of HS for BB3, BY28 and AR336 were %31, %50, and %91, respectively. An eco-friendly and low-cost HS for removal of dyes from the aqueous solution within 100 s – 1200 s; HS was proposed in wastewater treatment.

Ultrasonic-assisted recycling of Nile tilapia fish scale biowaste into low-cost nano-hydroxyapatite: Ultrasonic-assisted adsorption for Hg2+ removal from aqueous solution followed by "turn-off" fluorescent sensor based on Hg2+-graphene quantum dots.

This study was planned to recycle calcium and the phosphorus-rich Nile tilapia fish scale biowaste into nano-hydroxyapatite (FHAP), using ultrasonic-assisted extraction of calcium and phosphorus from fish scales, which was optimized in term of extraction time, acid concentration, extraction temperature, and ultrasonic power. These two elements were determined simultaneously by inductively coupled plasma atomic emission spectrometry and the FHAP phase was formed upon addition of the extracted element solution in alkaline medium using homogenous precipitation assisted with ultrasound energy. The FHAP adsorbent was characterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller. A combination of FHAP and the ultrasonic method was then used to remove Hg2+ from aqueous solution. Four significant variables affecting Hg2+ removal, namely, adsorbent dosage, pH, ultrasonic power, and adsorption time, were studied. The results exhibited that the optimal conditions for maximizing the removal of Hg2+ were 0.02g adsorbent dosage, pH 8, 0.4kW ultrasonic power, 20min adsorption time, and 30°C adsorption temperature. The sorption mechanism of Hg2+ was revealed by isotherm modeling, indicating that FHAP adsorbent has a potential for Hg2+ removal in aqueous media with the maximum adsorption capacity being 227.27mgg-1. This adsorption behavior is in agreement with the Langmuir model as reflected by a satisfactory R2 value of 0.9967, when the kinetics data were fitted with pseudo-second-order. Therefore, the FHAP could be an alternative adsorbent for the ultrasonic-assisted removal of Hg2+ at very high efficiency and within a very short period of time.

Ultrasonic-assisted modifications of macroporous resin to improve anthocyanin purification from a Pyrus communis var. Starkrimson extract.

The present study presents an attempt to modify the surface properties of macroporous resins (MRs) in order to improve anthocyanin adsorption and desorption from Pyrus communis var Starkrimson fruit peel extract. A number of MRs were tested to optimise the ultrasonic-assisted adsorption (UAA) conditions; including ultrasonic power (100-400 W), resin-to-extract ratio (1-3 g/50 mL) and temperature (20-40 °C). Similarly, varying ultrasonic-assisted desorption (UAD) conditions were optimised; including ultrasonic power (200-600 W), resin-to-solvent ratio (1-4 g/50 mL), ethanol concentration (60-90% v/v) and temperature (20-40 °C). The Amberlyst 15 (H) cationic resin was found to be superior to the other tested resins. The maximum adsorption capacity (659 µg/g) of cyanidin 3-galactoside (Cy 3-gal) was achieved under the optimised UAA conditions (400 W, 20 °C and 1 g/50 mL), while 616 µg/g of Cy 3-gal was recovered under the optimised UAD conditions (582 W, 1 g/50 mL, 60% and 20 °C). Moreover, titratable-acid and total-sugar contents were found to be significantly lower under UAA than under conventional-assisted adsorption (CAA). ANOVA revealed that process factors had significant effects on the Cy 3-gal purification, as depicted by their linear, quadratic and interactive effects. While anthocyanin adsorption was found to be significantly improved at lower ultrasonic power, higher power promoted the desorption process. Adsorption under optimized UAA conditions followed pseudo second-order kinetics and multilayer adsorption (Freundlich isotherm) onto the Amberlyst 15 (H) resin surface was observed. The particle-size distribution curve and scanning electron microscopic images also revealed higher resin-surface roughness, peeling and the appearance of pores on the surface under ultrasonication.This is the first study to use ultrasonication to modify a cationic exchange resin for the improvement of Cy 3-gal purification from a fruit extract. This study can recommend the use of ultrasonication as a low-cost green technique that can improve macroporous resin characteristics for better purification of compounds from an extract.

Titanium oxide nanoparticles loaded onto activated carbon prepared from bio-waste watermelon rind for the efficient ultrasonic-assisted adsorption of congo red and phenol red dyes from wastewaters

The simultaneous ultrasonic-assisted removal of Congo red (CR) and phenol red (Ph R) dyes from the aqueous solutions was accomplished by using titanium oxide (TiO2) nanoparticles (NPs) loaded onto activated carbon (AC) prepared from bio-waste watermelon rind (WR), referred to as TiO2–NPs–ACWR. The TiO2–NPs–ACWR was characterized by FT-IR, FESEM, SEM, EDX, BET, and TGA techniques. To simplify the optimization process, the pH effect was first studied via one-variable-at-a-time method. The influences of the other parameters such as sonication time, initial dyes concentrations, and adsorbent dosage were then evaluated by central composite design (CCD) combined with desirability function. The optimum conditions consisted of pH 4.3, 0.04 g of TiO2–NPs–ACWR, 8.22 min of sonication time, and initial concentrations of 45.9 mg L−1 and 14.7 mg L−1 for Ph R and CR, respectively, which resulted in high removal percentages (100.24% for Ph R and 101.45% for CR). Besides, the adsorption capacities were 55.6 mg g−1 for Ph R and 17 mg/g for CR. The adsorption equilibrium study showed that Langmuir model had adequate competence for the description and evaluation of the adsorption process. Kinetics study was carried out at various time intervals. The results indicated that adsorption processes can be fitted and predicated by the pseudo-second-order model.