“…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.
“…Among the various processes for removal of humic acid, the adsorption process, because of its high potential for removal of small molecules including organic material, seems to be one of the best solutions for wastewater treatment (8).…”
Background: Adsorption isotherms describe the relationship between the equilibrium concentration of the adsorbed matter in the solution and the amount of adsorbed matter on the surface of the adsorbent.
Objectives:The main objective of the present research was to investigate different adsorption isotherms for describing adsorption of humic acid by nanoclay.
Methods:In this study, Langmuir, Freundlich, BET, Temkin and Dubinin Radushkevich isotherms, for describing the behavior of humic acid adsorption by bentonite and montmorillonite nanoparticles, were examined.
Results:The results showed that due to the regression coefficient (R 2 ), humic acid adsorption on bentonite and montmorillonite nanoparticles has greater compliance with Dubinin Radushkevich isotherms. The value of E or average energy of adsorption for humic acid by bentonite and montmorillonite nanoparticles was 0.17 and 0.15 kJ mol -1 , respectively, which specifies that the type of adsorption of humic acid on both nanoparticles was physisorption. The qmax value obtained from the Dubinin-Radushkevich isotherms, for bentonite and montmorillonite nanoparticles were 27.78 and 28.70 mg/g, respectively.Conclusions: According to the results of this study, bentonite and montmorillonite nanoparticles have a great potential for the removal of humic acid from aqueous solutions.
“…According to Figure 7, as the sonication time advances, the humic acid concentration extracted from activated carbon increases, as well. In this regard, Hamdaoui et al studied the effects of ultrasonic process on adsorption of activated carbon and reported an improvement in regeneration efficiency as sonication time increases (15,31). The impact of the frequency of regeneration cycles on adsorption capacity is presented in Figure 8.…”
Section: Discussionmentioning
confidence: 99%
“…As in the first phase of saturation, the adsorption capacity was 42.94 mg/g, while it reduced to 42.14 mg/g after a regeneration cycle. The reduced adsorption capacity might be related to the deposition of decomposed residues in activated carbon pores, which blocked carbon porosity (11,13,15,30).…”
Section: Discussionmentioning
confidence: 99%
“…In pressure regeneration, atomic charge is usually applied (e.g., CO 2 ) (14). Ultrasonic regeneration has many advantages, such as removal of unwanted pollutants, decomposition of toxic organics, and most importantly saving energy, which increases the popularity of this method (15). Feng et al reported that organic and mineral particles on the adsorbent can be successfully released through the sonication process (16).…”
Background: Humic acid is a trihalomethane component in water supplies, causing various health disorders in humans. Objectives: This study was performed to examine humic acid adsorption on saturated activated carbon and to evaluate adsorbent regeneration through ultrasonic processes. Methods: In the present study, effects of various parameters, including initial concentration of humic acid, pH, contact time, adsorbent dose, and temperature, on the adsorption stage were investigated. Also, effects of different parameters, such as regeneration time, pH, and number of saturation-regeneration cycles, were studied in the regeneration stage. Results: The highest percentage of humic acid removal was reported at pH of three and initial humic acid concentration of 10 mg/L. The highest adsorption capacity of activated carbon was 29.7 mg/g at adsorbent dosage of 0.1 g/L and contact time of 10 minutes. The results of thermodynamic experiments showed that removal of humic acid by saturated activated carbon was endothermic. Also, maximum regeneration occurred at pH of 11 and contact time of 60 minutes. Finally, the adsorption capacity of saturated activated carbon changed from 42.94 to 42.14 mg/g after five cycles of saturation and regeneration.
Conclusions:The results of this study showed that activated carbon is an effective adsorbent in the removal of humic acid from water. Also, the ultrasonic process is effective in regeneration of activated carbon, saturated with humic acid.
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