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![Electronic images of the surfaces of the samples (a) F400, (b) F400An, and (c) F400NH 2 [48].](profile/Stanislav-Kulaishin/publication/361413762/figure/fig2/AS:11431281095351850@1667842030469/Electronic-images-of-the-surfaces-of-the-samples-a-F400-b-F400An-and-c-F400NH-2.png)
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![Fig. 1. Pore distribution for the samples F400, F400An, and F400NH 2 [48].](profile/Stanislav-Kulaishin/publication/361413762/figure/fig1/AS:11431281095309666@1667842030436/Pore-distribution-for-the-samples-F400-F400An-and-F400NH-2-48_Q320.jpg)
![Fig. 4. Chemical structures of (a) 2,4-D and (b) benazoline [89].](profile/Stanislav-Kulaishin/publication/361413762/figure/fig4/AS:11431281095342744@1667842030782/Chemical-structures-of-a-2-4-D-and-b-benazoline-89_Q320.jpg)
The influence of activation methods on the surface characteristics of activated carbons (ACs) and the relationships of these characteristics and the parameters of a medium with the efficiency of adsorption of herbicide molecules on ACs are considered. The main factors affecting the adsorption efficiency of ACs with respect to these pollutants are d...
Contexts in source publication
Context 1
... presence of acidic groups was determined by the degree of affinity for sodium ions [72]. Figure 2 shows the micrographs of the original sample ( Fig. 2a) and two samples subjected to additional processing. Figure 2 indicates how the surface of F400 AC changed in the course of amination and calcination. ...
Context 2
... oxygen groups and some other groups that are unstable to high temperatures, for example, weak acidic groups (phenolic, carboxyl, carbonyl, etc.) present in the original F400 sample, decreased. The presence of acidic groups was determined by the degree of affinity for sodium ions [72]. Figure 2 shows the micrographs of the original sample ( Fig. 2a) and two samples subjected to additional processing. Figure 2 indicates how the surface of F400 AC changed in the course of amination and calcination. Chingombe et al. [48] found that, on the calcination of the F400 sample, the formation of a larger fraction of micropores on the surface was observed, which can be explained by the ...
Context 3
... 2 shows the micrographs of the original sample ( Fig. 2a) and two samples subjected to additional processing. Figure 2 indicates how the surface of F400 AC changed in the course of amination and calcination. Chingombe et al. [48] found that, on the calcination of the F400 sample, the formation of a larger fraction of micropores on the surface was observed, which can be explained by the elimination of some oxygen-containing functional groups that are unstable at high temperatures. ...
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... In reviews by Kulaishin et al. 2022 [2] and Baskar et al. 2022 [3], adsorption on a variety of adsorbents, particularly on activated carbon (ACs), was emphasized as one approach for removing pesticides from the aqueous phase. There are certain drawbacks to other methods now in use, including the time needed for the process and reliance on environmental conditions for the biodegradation process, the need for energy for electrooxidation, and the photocatalytic process [2]. ...
... In reviews by Kulaishin et al. 2022 [2] and Baskar et al. 2022 [3], adsorption on a variety of adsorbents, particularly on activated carbon (ACs), was emphasized as one approach for removing pesticides from the aqueous phase. There are certain drawbacks to other methods now in use, including the time needed for the process and reliance on environmental conditions for the biodegradation process, the need for energy for electrooxidation, and the photocatalytic process [2]. ...
Adsorbents presenting high adsorption capacity, fast adsorption rate, easy regeneration, and a good possibility for reusability are ideal for removing 4-chloro-2-methyl-phenoxyacetic acid (MCPA) or other pesticides from wastewater. Here, the effects of regeneration treatments on adsorption–desorption cycles are examined using two commercial activated carbons (ACs) (Merck and Norit 1240 X). MCPA adsorption was fast on Merck and Norit ACs in powder form (6 h) but on Norit AC, in granular form, adsorption was too slow, and the equilibrium time was reached only after 288 h. MCPA adsorption kinetic data were analyzed by applying pseudo-first-order, pseudo-second-order, and Weber–Morris models. The pseudo-second-order model fit better to all data, and the Weber–Morris representation allows confirming that on Norit 1240 X, in granular form, the pore diffusion was the limiting factor concerning the MCPA adsorption. Merck and Norit 1240 X (in powder and granular form) ACs loaded with MCPA were submitted to different regeneration process by washing with distilled water, ethanol, HNO3, and NaOH solutions and washed with NaOH solutions or ethanol followed by a thermal treatment. The ACs regenerated with ethanol performed well in the subsequent adsorption–desorption cycles. All ACs had more than 99% desorbed MCPA after the first cycle of washing with ethanol. The washing with NaOH solution was less efficient. The regeneration process, consisting of washing the sample with a solution of NaOH and subsequent heating at 573 K, was very effective. After this regeneration procedure, the amount of MCPA adsorbed on Norit 1240 X AC was even higher than the amount adsorbed in the first adsorption cycle. At present, washing methods for adsorbent regeneration are not used at an industrial level. However, research for environmentally friendly regeneration methods is necessary to achieve the objectives of the circular economy.
... Among the most used methods for the removal of pesticides, from the aqueous phase, adsorption on a diversity of adsorbents, particularly on activated carbon (ACs) was highlighted, in reviews made by Kulaishin et. al in 2022 [1] and Baskar et. al, 2022 [2]. ...
... al, 2022 [2]. Some disadvantages concerning other methods currently used were identified, such as time consumption and dependency on environmental conditions for the biodegradation process, energy consumption for electrooxidation, and photocatalytic process [1]. ...
... Adsorption is a process with simple implementation and operation, being therefore widely used, for the removal of inorganic and organic contaminants from gaseous [3,4] or liquid effluents, such as drinking and wastewater [2]. However, adsorption present also has some limitations, such as adsorbent production cost, regeneration, and sustainable management of spent adsorbents [1][2][3][4][5]. ...
This paper describes the influence of the regeneration treatments on 4-chloro-2-methyl-phenoxyacetic acid (MCPA)-loaded activated carbons (ACs) on adsorption-desorption cycles with two commercial ACs, Merck and Norit 1240 X ( Norit 1240 X was used in a granular and powder form). The ACs were saturated with MCPA and then submitted to four regeneration cycles, by washing with ethanol, NaOH solutions and washed with NaOH solutions followed by a thermal treatment. The ACs regenerated with ethanol showed a better performance concerning the successive adsorption-desorption cycles. On the first cycle, the MCPA desorbed, from washing with ethanol, from all ACs was higher than 99%. After a fourth adsorption-desorption cycle, washing regeneration combined with thermal treatment allowed excellent regeneration results. The amount of MCPA adsorbed on Norit 1240 X AC was higher than the amount adsorbed in the first cycle. MCPA adsorption kinetic data were analyzed by applying pseudo-first-order, pseudo-second-order, and Weber-Morris models. The pseudo-second-order fit better fit to the data and the Weber-Morris representation allows confirming that on Norit 1240 X, in a granular form, the pore diffusion was the limiting factor concerning the MCPA adsorption.
... Finally, the maximum amount of each pesticide adsorbed on both ACs was slightly higher than the values obtained previously on ACs prepared from Tectona Grandis sawdust, by physical activation with CO 2 , at 973 K (maximum adsorption capacity of MCPA on Teak-7480 was 1.56 mmol·g −1 ) [10]. Nevertheless, these data compare favorably with published results obtained on a diversity of commercial ACs used for this purpose [10,39,40]. ...
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