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 The novel PEI-modified biochars and their application for the efficient elimination of Cr(VI) from aqueous solutions

2018 ◽  
Vol 77 (8) ◽  
pp. 2045-2056 ◽  
Author(s):  
Zhimin Lv ◽  
Shimin Yang ◽  
Yan Liu ◽  
Jin Zhou ◽  
Lingbao Xing ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
The Novel ◽  
Spectroscopy Analysis ◽  
Transmission Electron ◽  
Chestnut Shell ◽  
Batch Technique ◽  
Maximum Sorption ◽  
Efficient Elimination

Abstract In this study, the polyethyleneimine (PEI) was grafted onto the biochars from chestnut shells and nori via the cross-linking reaction. Scanning electron microscopy, transmission electron microscopy and Fourier transferred infrared spectroscopy analysis indicated that the PEI was successfully grafted on the surface of biochars. The PEI modified and pristine biochars were used as adsorbents to remove Cr(VI) from aqueous solutions as a function of pH, ionic strength, contact time and initial concentrations of Cr(VI) through batch technique. The strongly pH-dependent and ionic strength-independent of Cr(VI) sorption indicated that the sorption was mainly dominated by electrostatic interaction and inner-sphere surface complexation. The maximum sorption capacities of PEI modified chestnut shell and nori biochars were 141.42 and 222.84 mg/g, respectively, which were significantly higher than those of pristine biochars. The PEI grafted onto the biochars significantly enhanced Cr(VI) sorption capacity because PEI, which contains volumes of amine/imine groups, provided an excellent platform for Cr(VI) ions removal. In addition, the sorption–desorption experimental results indicated that the PEI modified biochars possessed a stable and recyclable performance. All these results manifested that the PEI modified biochars could be applied as environmentally friendly and efficient adsorbents for the removal of Cr(VI) from wastewater.

scholarly journals Batch equilibrium and kinetics of mercury removal from aqueous solutions using polythiophene/graphene oxide nanocomposite

2017 ◽  
Vol 75 (12) ◽  
pp. 2841-2851 ◽  
Author(s):  
Anthony M. Muliwa ◽  
Maurice S. Onyango ◽  
Arjun Maity ◽  
Aoyi Ochieng
Keyword(s):  
Graphene Oxide ◽  
Aqueous Solutions ◽  
Freundlich Isotherm ◽  
Significant Loss ◽  
Mercury Removal ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Equilibrium Studies ◽  
Mercury Uptake

Polythiophene/graphene oxide (PTh/GO) nanocomposite (NC) was prepared through polymerisation of thiophene in the presence of GO and was used for mercury ions (Hg2+) adsorption in aqueous solutions. Equilibrium studies showed that mercury removal was strongly influenced by solution pH and GO composition in the NC. The equilibrium data were well described by both Langmuir and Freundlich isotherm models, with a Langmuir maximum adsorption capacity of 113.6 mg/g. Adsorption kinetics were rapid and correlated well with the pseudo-second-order model. The thermodynamic studies indicated that the adsorption was spontaneous and endothermic in nature, and occurred through a physicochemical mechanism. Desorption studies revealed that PTh/GO NC could be used repeatedly for three adsorption-desorption cycles without a significant loss in its capacity. Competing ions reduced mercury uptake although considerable values were still attained. The findings of this study suggest that PTh/GO NC is a potential adsorbent for Hg2+ removal from aqueous 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.

Trace Metal Soil Quality Criteria to Protect Ground Water

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2327-2329
Author(s):  
J. Lee ◽  
B. Chen ◽  
H. E. Allen ◽  
C. P. Huang ◽  
D. L. Sparks ◽  
...  
Keyword(s):  
Drinking Water ◽  
Quality Criteria ◽  
Maximum Level ◽  
Inorganic Materials ◽  
Decision Making Process ◽  
Water Quality Standards ◽  
Solution Ph ◽  
Drinking Water Standard ◽  
Cadmium And Lead ◽  
Adsorption Desorption

A major problem in site remediation is frequently the lack of appropriate standards for pollutants in soil. Lack of standards for an exposure route can result in subjective judgments regarding the extent of remediation needed. These problems are particularly important when considering the potential for groundwater contamination by inorganic materials. The partitioning of trace metals is highly dependent on the nature of the soil and on the solution pH. The maximum level of metal in soil for which the equilibrium soluble metal does not exceed the drinking water standard can be computed, at any pH, from the measured partition coefficient for any metal and soil. The sorption of cadmium and lead onto major types of New Jersey soil has been determined as a function of pH. As the pH decreased, the amount of adsorbed metal decreased. As is conventionally done, we have transformed these data into sorption coefficients (Kd) which are a function of pH. To apply such data in the decision making process, it is necessary to use the Kd and appropriate conditions of soil/groundwater in the environment. The calculation determines the maximum concentration of metal which will not result in exceedence of water quality standards. Thesecriteria can be used as a soil standard which will be protective of groundwater quality. We developed adsorption/desorption relationships in the form of a mathematical model and computed the maximum level of metal in soil for which the equilibrium soluble metal will not exceed the drinking water standards.

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 Effect of pyrolysis temperature on Si release of alkali-enhanced Si-rich biochar and plant response

Biochar ◽  
2021 ◽  
Author(s):  
Meng Wang ◽  
Negar D. Tafti ◽  
Jim J. Wang ◽  
Xudong Wang
Keyword(s):  
Rice Straw ◽  
Rice Husk ◽  
Pyrolysis Temperature ◽  
Weak Acid ◽  
Rice Grain ◽  
Neutral Salt ◽  
Salt Solutions ◽  
Plant Disease Control ◽  
Si Content ◽  
Lower Temperature

AbstractRecent studies have shown that silicon (Si) dissolution from biochar may be influenced by the pyrolysis temperature. In addition, the enhancement of biochar by treatment with alkali has been proposed to produce a Si source that can be used for environmentally friendly plant disease control. In this study, biochars from rice straw and rice husk pretreated with KOH, CaO and K2CO3 and then pyrolyzed at 350, 450 and 550 °C were prepared to evaluate the effects of pyrolysis temperature on Si release and plant uptake from alkali-enhanced Si-rich biochar. Extractable Si and dissolution Si from the prepared biochars were assessed by different short-term chemical methods and long-term (30-day) release in dilute acid and neutral salt solutions, respectively, along with a rice potting experiment in greenhouse. For both rice straw- and husk-derived alkali-enhanced biochars (RS-10KB and HS-10K2B, respectively), increasing the pyrolysis temperature from 350 to 550 °C generally had the highest extractable Si and increased Si content extracted by 5-day sodium carbonate and ammonium nitrate (5dSCAN) designated for fertilizer Si by 61–142%, whereas non-enhanced biochars had more extractable Si at 350 °C. The alkali-enhanced biochars produced at 550 °C pyrolysis temperature also released 82–172% and 27–79% more Si than that of 350 °C produced biochar in unbuffered weak acid and neutral salt solutions, respectively, over 30 days. In addition, alkali-enhanced biochars, especially that derived from rice husk at 550 °C facilitated 6–21% greater Si uptake by rice and 44–101% higher rice grain yields than lower temperature biochars, non-enhanced biochars, or conventional Si fertilizers (wollastonite and silicate calcium slag). Overall, this study demonstrated that 550 °C is more efficient than lower pyrolysis temperature for preparing alkali-enhanced biochar to improve Si release for plant growth.

Oxidized biochar obtained from rice straw as adsorbent to remove uranium (VI) from aqueous solutions

2021 ◽  
Vol 9 (2) ◽  
pp. 105104
Author(s):  
Waqas Ahmed ◽  
Sajid Mehmood ◽  
Muhammad Qaswar ◽  
Sehrish Ali ◽  
Zulqarnain Haider Khan ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Rice Straw
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