scholarly journals Performance of an acid stable nanofiltration membrane for nickel removal from aqueous solutions: effects of centration, solution pH and ionic strength

2012 ◽  
Author(s):  
O. Agboola ◽  
J. J. Schoeman ◽  
J. Maree ◽  
R. Mbaya ◽  
A. Kolesnikov
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Nanofiltration Membrane ◽  
Solution Ph ◽  
Nickel Removal ◽  
Acid Stable

scholarly journals Kinetic and Equilibrium Studies on the Zinc Adsorption-desorption Characteristics of Some Promising Biochars in Aqueous Solutions

2021 ◽  
Author(s):  
Masoumeh Faryadi Shahgoli ◽  
Adel Reyhanitabar ◽  
Nosratollah Najafi ◽  
Shahin Oustan
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Rice Straw ◽  
Pyrolysis Temperature ◽  
Ph Effect ◽  
Solution Ph ◽  
Equilibrium Studies ◽  
Batch Technique ◽  
Adsorption Desorption ◽  
Zinc Adsorption

Abstract The present research aimed at investigating zinc (Zn) sorption capacity of the biochars derived from apple wood (WB) and rice straw (RB) feedstocks at two 300 and 600°C pyrolysis temperatures (WB300, WB600, RB300 and RB600, respectively) in aqueous solutions. Kinetic and equilibrium sorption experiments were conducted via batch technique. In equilibrium adsorption experiments, the study used the concentration range of 5-200 mg Zn L− 1 and focused on the solution pH effect on Zn adsorption in biochars under the following conditions: unadjusted and adjusted pH (4 and 6) and three ionic strength levels (0.01, 0.03, 0.1 M KNO3). Zinc desorption experiments were conducted under all above mentioned conditions but without pH adjustment at five separate stages. Kinetic data analysis indicated that Zn adsorption in biochars reached the near steady state within 24 hours with the sorption rate order of WB300 < WB600 < RB300 < RB600. The best fitness was superior to both Elovich and exponential rate models. Also, Zn adsorption isotherms in the studied biochars were shown to fit quite well to Langmuir, Freundlich and Dubinin-Radushkevich models. Zn sorption maxima were found to be 4.3, 16.4, 17.9 and 33.3 mg g− 1, on average, for WB300, WB600, RB300, and RB600, respectively. The initial increased pH solution from 4 to 6 caused an increase in Zn adsorption in RB600, RB300 and WB600, however the sorption maxima in WB300 was detected at pH 4. The rise in solution ionic strength from 0.01 M to 0.1 M dropped the Zn adsorption capacity in all the studied biochars. Findings suggested that rice straw derived biochars showed a better performance than woody biochars in Zn sorption and retention from aqueous solutions. In addition, this ability increased with increasing pyrolysis temperature in both types of biochars. Finally, the study revealed that rice straw biochars, produced at high pyrolysis temperatures, can serve as economical and efficient absorbents for Zn removal from aqueous solutions.

scholarly journals Effect of Praestol as a Coagulant-Aid to Improve Coagulation-Flocculation in Dye containing Wastewaters

2015 ◽  
Vol 18 (1) ◽  
pp. 38-46 ◽  
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Removal Efficiency ◽  
Dye Removal ◽  
Settling Time ◽  
Solution Ph ◽  
Polyaluminum Chloride ◽  
Flocculation Process ◽  
Flocculation Time

<div> <p>This study was conducted to investigate the effect of praestol, as a coagulant-aid, to improve coagulation-flocculation process in the removal of disperse red 60 from aqueous solutions. The effect of various parameters including coagulants dose (10-1000 mg l<sup>-1</sup>), praestol dose (0-1000 mg l<sup>-1</sup>), solution pH (3-11), initial dye concentration (100-500 mg l<sup>-1</sup>), flocculation speed (30-60 rpm), flocculation time (15-30 min), settling time (5-60 min) and ionic strength (0-6 mg l<sup>-1</sup>) was evaluated on the dye removal. The dye removal efficiency was substantially increased by using praestol in the concentration of 80 mg l<sup>-1 </sup>and 400 mg l<sup>-1 </sup>for coagulation with alum and polyaluminum chloride (PACl), respectively. The maximum dye removal by alum coupled with praestol (Al-P) and PACl coupled with praestol (PA-P) was found to be 97.8% and 98.7%, respectively that were occurred at pH 7. The results showed that the application of PA-P or Al-P can be effectively used to remove disperse red 60 (DR 60) in aqueous solutions.</p> </div> <p>&nbsp;</p>

scholarly journals Assessment of the Total Volume Membrane Charge Density through Mathematical Modeling for Separation of Succinic Acid Aqueous Solutions on Ceramic Nanofiltration Membrane

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 559 ◽  
Author(s):  
Agata Marecka-Migacz ◽  
Piotr Tomasz Mitkowski ◽  
Jerzy Antczak ◽  
Jacek Różański ◽  
Krystyna Prochaska
Keyword(s):  
Mathematical Modeling ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Succinic Acid ◽  
Ceramic Membrane ◽  
Ph Regulation ◽  
Nanofiltration Membrane ◽  
Charge Densities ◽  
Membrane Charge ◽  
Insight Into

Nanofiltration of aqueous solutions of succinic acid with the addition of sodium hydroxide or magnesium hydroxycarbonate has been investigated experimentally and modeled with the comprehensively described Donnan–Steric partitioning model. The experimental retentions of acid at the same pH varied between 16% and 78%, while the estimated total volume membrane charge densities were in the range of −35.73 and +875.69 mol/m3. This work presents a novel insight into the modeling of nanofiltration and investigates the relations between the estimated total volume membrane charge densities, ionic strength, and component concentration on the performance of ceramic membrane. In addition, this study takes into consideration other parameters such as pH regulation and viscosities of solutions.

scholarly journals Interactions between adsorbents and adsorbates in aqueous solutions

2020 ◽  
Vol 92 (10) ◽  
pp. 1655-1662
Author(s):  
Zhijian Wu ◽  
Xiushen Ye ◽  
Haining Liu ◽  
Huifang Zhang ◽  
Zhong Liu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Adsorption Capacity ◽  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Solution Ph ◽  
Electrostatic And Hydrophobic Interactions

AbstractAdsorption is one of the most widely used processes in physicochemical operations. To design an adsorbent for a specific adsorbate, it is important to understand the interactions between adsorbents and adsorbates, which are very important for both adsorption capacity and selectivity. Electrostatic interactions, hydrogen bonding, hydrophobic interactions, complexation, and precipitation are comprehensively discussed. Adjusting solution pH and ionic strength is an effective method to improve the adsorption, especially when electrostatic and hydrophobic interactions are main interactions. With the increase in ionic strength, the hydrophobic interactions between adsorbents and adsorbates increase, while the electrostatic interactions decrease.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

scholarly journals Oxytetracycline Adsorption from Aqueous Solutions on Commercial and High-Temperature Modified Activated Carbons

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3481
Author(s):  
Joanna Lach ◽  
Agnieszka Ociepa-Kubicka ◽  
Maciej Mrowiec
Keyword(s):  
Activated Carbon ◽  
Aqueous Solutions ◽  
Activated Carbons ◽  
Electricity Consumption ◽  
Solution Ph ◽  
Carbon Modification ◽  
Modification Method ◽  
Flow Through ◽  
Proposed Modification ◽  
Modified Activated Carbons

The aim of the work was to evaluate the possibility of using commercial and modified activated carbons for the removal of oxytetracycline from aqueous solutions. The kinetics and statics of adsorption as well as the effect of the activated carbon dose and solution pH on the efficiency of the oxytetracycline adsorption were analyzed. Based on the study of oxytetracycline adsorption isotherms, the activated carbons were ranked in the following order: F-300 > WG-12 > Picabiol > ROW08 > WACC 8 × 30 > F-100 > WAZ 0.6–2.4. The most effective activated carbons were characterized by large specific surfaces. The best matching results were obtained for: Redlich–Peterson, Thot and Jovanovic models, and lower for the most frequently used Freundlich and Langmuir models. The adsorption proceeded better from solutions with pH = 6 than with pH = 3 and 10. Two ways of modifying activated carbon were also assessed. A proprietary method of activated carbon modification was proposed. It uses the heating of activated carbon as a result of current flow through its bed. Both carbons modified at 400 °C in the rotary kiln and on the proprietary SEOW (Joule-heat) modification stand enabled to obtain adsorbents with higher and comparable monolayer capacities. The advantage of the proposed modification method is low electricity consumption.

scholarly journals Adsorption of Pollutants from Aqueous Solutions Using Activated and Non-Activated Oak Shells: Parametric and Fractional Factorial Design Study. Part II. Removal of Phenol and Dyes

2003 ◽  
Vol 21 (2) ◽  
pp. 189-198
Author(s):  
Sameer Al-Asheh ◽  
Fawzi Banat ◽  
Rana Saeidi ◽  
Salam Abu Zaid
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Factorial Design ◽  
Fractional Factorial Design ◽  
Sorption Process ◽  
Fractional Factorial ◽  
Phenol Concentration ◽  
Blue Dye ◽  
Batch Adsorption ◽  
Solution Ph

As in Part I, non-activated (natural) and chemically activated oak shells were evaluated for their ability to remove phenol and Methylene Blue (as a typical dye component) from aqueous solutions. Batch adsorption experiments were conducted to investigate the effect of contact time, sorbent concentration, phenol concentration and the pH of the solution on the sorption process. Activated oak shells adsorbed more phenol than natural oak shells under the same conditions. A decrease in sorbent concentration or an increase in phenol concentration or solution pH resulted in an increase in phenol uptake by the oak shells. The uptake of Methylene Blue increased with decreasing sorbent concentration and with an increase in the dye concentration, but decreased significantly with solution pH. According to the fractional factorial design technique, the sorbent type employed (natural or activated) had the most significant influence on phenol or Methylene Blue uptake followed by sorbent concentration and then sorbate concentration. Interaction amongst the different operating variables played an important role in the uptake of phenol or Methylene Blue dye by the adsorbent considered.

Effect of ionic strength on the aggregation kinetics of the amidated amyloid beta peptide Aβ (1-40) in aqueous solutions

2017 ◽  
Vol 228 ◽  
pp. 98-107 ◽  
Author(s):  
Adriana Campos-Ramírez ◽  
Maripaz Márquez ◽  
Liliana Quintanar ◽  
Luis F. Rojas-Ochoa
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Amyloid Beta ◽  
Amyloid Beta Peptide ◽  
Aggregation Kinetics ◽  
Beta Peptide ◽  
Kinetics Of
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