Abstract:a b s t r a c tThe presence of humic acid, as one of the precursors of trihalomethanes, in water resources causes many health problems for many communities. The purpose of the present study was to investigate the feasibility of ultrasonic process on regeneration of graphene nanoparticles saturated with humic acid. This experimental study was performed in batch condition, which the effects of main parameters such as regeneration time, pH, number of saturation cycles and frequency were investigated for the regen… Show more
“…2c and d). The results of the present work show that the generation of RPG can be re-used decreases from cycle 1 to cycle 4 is in agreement with previous studies [69, 70, 71, 72]. These results also show that RPG is an excellent reusable and easily regenerated adsorbent for the removal of both Cd 2+ and Cr 3+ ions from the aqueous environment.Fig.…”
Recently, a great attention has been given for applying a low-cost and effective adsorbents instead of expensive and dangerous chemical materials as a promising approach to treat wastewater. In this work, residue powder of brown macroalga
Padina gymnospora
(RPG), after extracting most of its active components by 70% methanol, was used as an adsorbent material for wastewater treatment. This work also reduces the costs of residue disposal. The adsorption ability of RPG is studied for removing Cd
2+
and Cr
3+
from wastewater. We investigated metal adsorption isotherms and kinetics, the effect of initial metal concentration, contact time, adsorbent dosage, temperature, pH and the RPG reusability on metal ions removal. The results showed that the removal % generally increases with decreasing concentration of metal ions. RPG has higher metal removal percentages reaching 96.2% and 78.8% for Cd
2+
and Cr
3+
, respectively, with a maxiumum adsorption capacity of 96.46 and 31.52 mg/g for
Cd
2+
and Cr
3+
,respectively at pH 6.2, 50 mg, 25 °C and initial metal concentration of 100 mg/L. The metal ions removal % increased by increasing the dosage of adsorbent and it decreased after a certain limit. The metal removal % slightly changes with increasing temperature for Cd
2+
and decreased at high-temperature for Cr
3+
. The adsorption increased with increasing pH value from 3 to 5, and decreases at pH value of 6.2 then it increased again at pH 8. The removal % and adsorption capacity at pH 8 reaches 99.58%, 99.65%, 99.85 mg/g and 39.86 mg/g for Cd
2+
and Cr
3+
, respectively. The results also showed that RPG can be reused several times for metal ions removal. In addition, Tempkin isotherms and pseudo-second-order kinetic fit the adsorption of Cd
2+
and Cr
3+
well.
“…2c and d). The results of the present work show that the generation of RPG can be re-used decreases from cycle 1 to cycle 4 is in agreement with previous studies [69, 70, 71, 72]. These results also show that RPG is an excellent reusable and easily regenerated adsorbent for the removal of both Cd 2+ and Cr 3+ ions from the aqueous environment.Fig.…”
Recently, a great attention has been given for applying a low-cost and effective adsorbents instead of expensive and dangerous chemical materials as a promising approach to treat wastewater. In this work, residue powder of brown macroalga
Padina gymnospora
(RPG), after extracting most of its active components by 70% methanol, was used as an adsorbent material for wastewater treatment. This work also reduces the costs of residue disposal. The adsorption ability of RPG is studied for removing Cd
2+
and Cr
3+
from wastewater. We investigated metal adsorption isotherms and kinetics, the effect of initial metal concentration, contact time, adsorbent dosage, temperature, pH and the RPG reusability on metal ions removal. The results showed that the removal % generally increases with decreasing concentration of metal ions. RPG has higher metal removal percentages reaching 96.2% and 78.8% for Cd
2+
and Cr
3+
, respectively, with a maxiumum adsorption capacity of 96.46 and 31.52 mg/g for
Cd
2+
and Cr
3+
,respectively at pH 6.2, 50 mg, 25 °C and initial metal concentration of 100 mg/L. The metal ions removal % increased by increasing the dosage of adsorbent and it decreased after a certain limit. The metal removal % slightly changes with increasing temperature for Cd
2+
and decreased at high-temperature for Cr
3+
. The adsorption increased with increasing pH value from 3 to 5, and decreases at pH value of 6.2 then it increased again at pH 8. The removal % and adsorption capacity at pH 8 reaches 99.58%, 99.65%, 99.85 mg/g and 39.86 mg/g for Cd
2+
and Cr
3+
, respectively. The results also showed that RPG can be reused several times for metal ions removal. In addition, Tempkin isotherms and pseudo-second-order kinetic fit the adsorption of Cd
2+
and Cr
3+
well.
“…Furthermore, high performance, short duration, and environmental soundness are other benefits of the adsorbent ultrasonic modification [19]. Naghizadeh et al (2017) regenerated as 85.37% and 72.47% of graphene nanoparticles with an ultrasonic process at pH of 11 during 60 min and frequencies of 60 kHz and 37 kHz, respectively, [22]. Similar results were obtained in the related literature.…”
Section: M-mwcnts Characteristicssupporting
confidence: 64%
“…Naghizadeh et al (2017) reported that we can regenerate graphene nanoparticles with an ultrasonic process as 85.37% and 72.47% at frequencies of 60 kHz and 37 kHz, respectively. [22]. However, we assumed that the modification of adsorbent surface by using these methods could increase the efficiency of removal of pollen adsorbents.…”
The removal of pharmaceutical pollutants from the aqueous environment is a great environmental concern, mainly due to their diversity, high consumption, and sustainability. In the current study, we aimed to investigate the ability of multi-walled carbon nanotubes (MWCNTs) modified by sodium hypochlorite (NaOCl) and ultrasonic treatment in refining wastewaters contaminated with Atenolol β-blocker drug (ATN). The physical and structural characteristics of the raw MWCNTs and modified MWCNTs (M-MWCNTs) were analyzed using SEM, TEM, Raman spectroscopy, TGA, and FT-IR techniques. The effects of different parameters, including pH, initial concentration, contact time, and temperature were studied and optimized. Subsequently, the adsorption data were analyzed by several kinetic and equilibrium isotherm equations and modeled by artificial neural network (ANN). Highest ATN removal (87.89%) ((q e,exp = 46.03 mg g −1)) occurred on the adsorbent activated within 10 s of ultrasonication time and NaOCl 30%. Moreover, adsorbent modification significantly improved the ATN removal, so that the removal rate on the raw MWCNTs was about 58%, but in the same conditions, M-MWCNTs removed more than 92% of the adsorbate. The adsorption process reached equilibrium after 90 min under the optimized pH of 6. According to ANN modeling, approximately the whole values dispersed around the 45°line, indicating a good compatibility between the trial results and ANNpredicted data. The modification of MWCNTs in proper ultrasonic power via appropriate concentration of NaOCl solution removed many of the impurities and significantly improved the adsorption performance of MWCNTs.
“…ey reported the maximum regeneration efficiency, at a pH of 11 and a regeneration time of 60 min, was 85.37% and 72.47% for frequencies of 60 and 37 kHz, respectively [33].…”
Atenolol (ATN) is a β-blocker drug extensively used to treat arrhythmias and high blood pressure. Because the human body cannot metabolize it completely, this drug has been commonly found in many environmental matrices. In the present study, the response surface method (RSM) was used for adsorption prediction of ATN on modified multiwalled carbon nanotubes (M-MWCNTs) by NaOCl and ultrasonic. The sensitivity analysis was done by the Monte Carlo method. Sensitivity analysis was performed to determine the effective parameter by the Monte Carlo simulator. Statistical analysis of variance (ANOVA) was performed by using the nonlinear second-order model of RSM. The influential parameters including contact time (min), adsorbent dosage (g/L), pH, and the initial concentration (mg/L) of ATN were investigated, and optimal conditions were determined. Kinetic of ATN adsorption on M-MWCNTs was evaluated using pseudo-first, pseudo-second-order, and intraparticle diffusion models. Equilibrium isotherms for this system were analyzed by the ISOFIT software. As per our result, optimum conditions in the adsorption experiments were pH 7, 60 min of contact time, 0.5 mg/L ATN initial concentration, and 150 mg/L adsorbent dose. In terms of ATN removal efficiency, coefficients of R2 and adjusted R2 were 0.999 and 0.998, respectively. Sensitivity analysis also showed that contact time has the greatest effect on increasing the removal of ATN. Pseudo-first-order (R2 value of 0.99) was the best kinetic model for the adsorption of ATN, and for isotherm, BET (AICC value of 3.27) was the best model that fit the experimental data. According to the obtained results from sensitive analysis, time was the most important parameter, and after that, the adsorbent dose and pH affect positively on ATN removal efficiency. It can be concluded that the modified multiwalled carbon nanotubes can be applied as one of the best adsorbents to remove ATN from the aqueous solution.
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