Figure 7 - uploaded by Lorena Dornelas Marsolla
Content may be subject to copyright.
Effect of the dosage of activated carbon (PAC1 and PAC2) on the 2,4-D removal rate in ultrapure water (UW) and natural water (NW). Error bars represent the standard deviation.
Source publication
The presence of microcontaminants in the water supply system offers adverse impacts. This study analyzed the performance of two powdered activated carbons (PAC1 and PAC2) in the removal of 2,4-D herbicide in ultrapure water (UW) and natural water (NW) to verify the influence of natural organic matter (NOM) on the adsorptive process. The properties...
Context in source publication
Context 1
... regarding the adsorption of micropollutants such as 2,4-D. [50,51] The degree of adsorption competition of NOM depends on the composition of the NOM which varies with the type of water. [54,55] The effect of adsorbent dosage on the removal of 2,4-D was evaluated by varying the dosage of PAC1 and PAC2 adsorbents from 0.25 to 2.00 g in UW and NW (Fig. 7). As the adsorbent mass increases, so does the removal of 2,4-D on account of carbon sites availability for the adsorption process. [23,34] In UW, the 2,4-D removal by PAC1 and PAC2 became stable after a 0.75 mg dose; to achieve herbicide removal above 90%, 0.75 g of PAC1 and 0.50 g of PAC2 are needed. In NW, removal stability of 2,4-D ...
Similar publications
![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...
Citations
... Agricultural wastes have been considered an excellent option due to their cost-effectiveness, availability, and dual benefits for both economic and environmental purposes. Marsolla et al [19] studied the adsorption of 2,4-D herbicide using activated carbons. There have been numerous studies on the production of AC from agricultural by-products including bamboo waste [20], rambutan peel [21], pistachio shell [22], water caltrop husk [23], walnut shells [24], apricot stones [25] and olive-waste [26]. ...
2,4-Dichlorophenoxyacetic acid (2,4-D) herbicide is a widely utilized herbicide known to be moderately toxic, have extensive use, poor biodegradability, and h led to contamination of surface and ground waters. The Granular Activated Carbon (GAC) was characterized by its porosity, surface morphology, and availability of functional groups. Type I isotherm was observed in the GAC, indicating microporosity with specific a surface area of 832.35 m2/g and pore diameter of 0.899 nm. GAC was evaluated for its ability to adsorb herbicide 2,4-D as the model adsorbate and evaluated the effects of initial concentration, contact time, pH, and activated carbon dosage on the adsorption process. According to the results, 94.01 %, 97.17%, 97.76 %, 98.15%, and 98.2 % of the adsorptive removal were achieved at initial concentrations of 10, 20, 30, 40, and 50 mg/l, respectively. Langmuir and Freundlich isotherm models were used to analyze the adsorption isotherm. It was determined that 2,4-D had a maximum monolayer adsorption capacity of 20.28 mg/g for GAC. Freundlich isotherm model predicted uniform binding energy distribution over heterogeneous surface binding sites for the best fit. The Freundlich model was used to design a batch adsorber capable of removing 2,4-D from effluent solutions of different volumes using the required mass of GAC. Resulting of the achieved results, GAC is a highly effective adsorbent for the removal of 2,4-D from aqueous environments.
... On the other hand, the effects of competitive and pore blockage of NOM might be less significant for mesoporousactivated carbons. 30 Depending on the characteristic of NOM specific to the water source and the pore size distribution and size of activated carbon, the degree of the competitive effect of NOM against micropollutants can be different. Specific UV absorbance (SUVA) represents the numerical quantity of aromatic content and the humic fraction, since the aromatic structure of NOM containing conjugated C�C double bonds absorbs UV light at 254 nm. ...
Although activated carbon adsorption is a very promising process for the removal of organic compounds from surface waters, the removal performance for nonionic pesticides could be adversely affected by co-occurring natural organic matter. Natural organic matter can compete with pesticides during the adsorption process, and the size of natural organic matter affects the removal of pesticides, as low-molecular-weight organics directly compete for adsorbent sites with pesticides. This study aims to investigate the competitive impact of low-molecular-weight organics on the adsorptive removal of acetochlor and metolachlor by four commercial powdered activated carbons. The adsorption features of selected powdered activated carbons were evaluated in surface water samples collected from the influent stream of the filtration process having 2.75 mg/L organic matter and 0.87 L/mg-m specific UV absorbance. The adsorption kinetics and capacities were examined by employing pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models and modified Freundlich and Langmuir isotherm models to the experimental data. The competitive removal of acetochlor and metolachlor in the presence of natural organic matter was evaluated for varied powdered activated carbon dosages on the basis of UV and specific UV absorbance values of adsorbed organic matter. The adsorption data were well represented by the modified Freundlich isotherm, as well as pseudo-second-order kinetics. The maximum organic matter adsorption capacities of the modified Freundlich isotherm were observed to be 120.6 and 127.2 mg/g by Norit SX Ultra and 99.5 and 100.6 mg/g by AC Puriss for acetochlor- and metolachlor-containing water samples, respectively. Among the four powdered activated carbons, Norit SX Ultra and AC Puriss provided the highest natural organic matter removal performances with 76 and 72% and 71 and 65% for acetochlor- and metolachlor-containing samples, respectively. Similarly, Norit SX Ultra and AC Puriss were very effective for adsorbing aromatic organics with higher than 80% specific UV absorbance removal efficiency. Metolachlor was almost completely removed by higher than 98% by Norit SX Ultra, Norit SX F Cat, and AC Puriss, even at low adsorbent dosages. However, an adsorbent dose of 100 mg/L and above should be added for all powdered activated carbons, except for Norit SX F Cat, for achieving an acetochlor removal performance of higher than 98%. The competition between low-molecular-weight organics (low-specific UV absorbance) and acetochlor and metolachlor was more apparent at low adsorbent dosages (10-75 mg/L).
... These adsorbents are readily available and produced in large quantities. In research, they are used either in the form provided by the manufacturer [23,73,[76][77][78][79][80][81][82][83][84][85][86][87] or washed with distilled water at different temperatures or process times [23,70,72,[88][89][90][91][92][93]. The reason for doing so is to wash out the water-soluble components of the ash contained in commercial activated carbons. ...
The increasing consumption of phenoxyacetic acid-derived herbicides is becoming a major public health and environmental concern, posing a serious challenge to existing conventional water treatment systems. Among the various physicochemical and biological purification processes, adsorption is considered one of the most efficient and popular techniques due to its high removal efficiency, ease of operation, and cost effectiveness. This review article provides extensive literature information on the adsorption of phenoxyacetic herbicides by various adsorbents. The purpose of this article is to organize the scattered information on the currently used adsorbents for herbicide removal from the water, such as activated carbons, carbon and silica adsorbents, metal oxides, and numerous natural and industrial waste materials known as low-cost adsorbents. The adsorption capacity of these adsorbents was compared for the two most popular phenoxyacetic herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA). The application of various kinetic models and adsorption isotherms in describing the removal of these herbicides by the adsorbents was also presented and discussed. At the beginning of this review paper, the most important information on phenoxyacetic herbicides has been collected, including their classification, physicochemical properties, and occurrence in the environment.
Emerging pollutants are a widespread environmental concern, andadsorption represents one of the choices available for the removal of suchcompounds from polluted waters. However, the set‐up of a new adsorption system requiresthe experimental determination of adsorption isotherms and their thoroughmodelling, for the sake of a convenient optimization. In this work, the Campomanesia guazumifolia biomass is adopted as precursor for the synthesis of anew adsorbent and then tested for the adsorption of KTP and 2,4‐D. Theadsorption performances of this biomass are significantly improved through atreatment with sulfuric acid, which allows obtaining higher removal efficiency ofthe target organic molecules. The experimental isotherms are measured at 298 – 328 K and pH 2. An ETAM model is employed for amodeling analysis of the experimental data, for the comprehension of theoccurring adsorption mechanism. Results demonstrated that adsorption of KTP isendothermic and occurs in multilayer with a multimolecular process, in whichthe molecular aggregation can be predicted. On the contrary, the adsorption of 2,4‐D on this functionalized biomass is exothermic. The adsorption energiesresulted to be < 40 kJ mol⁻¹, indicating that physical adsorption forces are involved inthe removal of these organic molecules.
The search for efficient adsorbents to mitigate the impact of antibiotic pollutants on marine ecosystems, food security and human health is a burgeoning field of research. Further, Trimethoprim (TMP) and sulfamethoxazole (SMX) are widely distributed in the marine environment and are difficult to degrade. In this research, we used gravity separation to enrich the residual carbon from the coal gasification coarse slag and used the resulting carbon-high product (GC) as a low-cost and high-efficiency adsorbent. TMP and SMX were investigated for their adsorption behavior in seawater using GC under varied conditions. The findings indicated that the adsorption capacities of TMP and SMX by GC were 5.0017 mg/g and 5.1391 mg/g, respectively. The equilibrium durations of TMP and SMX by GC were 21 min and 40 min, respectively. Various adsorption models were fitted to the adsorption behavior of two pollutants by GC. The results showed that the adsorption processes of the two pollutants were consistent with the Freundlich equation and the quasi-secondary kinetic model, suggesting that both pollutants were adsorbed on GC surface by both physical and chemical processes. GC more effectively adsorbed TMP than SMX under a competitive adsorption procedure. When we introduced molecular dynamics simulation into this research, the microscopic procedures of GC adsorbing two pollutants were investigated. The energy composition and hydrogen bond types in the adsorption process were quantified. Finally, we summarized the adsorption mechanism of GC adsorbing two pollutants. This work will pave the way for developing effective, low-cost and environmentally friendly novel materials for the adsorption and purification of antibiotic pollutants in the marine environment. This research can produce positive economic and environmental effects in the comprehensive utilization of coal gasification slag.
Two cyclodextrin-based nanosponges (CD-NSs) were synthesized using diamines with 6 and 12 methylene groups, CDHD6 and CDHD12, respectively, and used as adsorbents to remove 2,4-D from aqueous solutions. The physico-chemical characterization of the CD‒NSs demonstrated that, when using the linker with the longest chain length, the nanosponges show a more compact structure and higher thermal stability, probably due to hydrophobic interactions. SEM micrographs showed significant differences between the two nanosponges used.
The adsorption of 2,4-D was assessed in terms of different parameters, including solid/liquid ratio, pH, kinetics and isotherms. Adsorption occurred preferentially at lower pH values and for short-chain crosslinked nanosponges; while the former is explained by the balance of acid-base characteristics of the adsorbent and adsorbate, the latter can be justified by the increase in the crosslinker-crosslinker interactions, predominantly hydrophobic, rather than adsorbent-adsorbate interactions. The maximum adsorption capacity at the equilibrium (qe) was 20,903 mmol/kg, obtained using CDHD12 with an initial 2,4-D concentration of 2 mmol/L. An environmentally friendly strategy, based on alkali desorption, was developed to recycle and reuse the adsorbents. On the basis of the results obtained, cyclodextrin-based nanosponges appear promising materials for an economically feasible removal of phenoxy herbicides, to be used as potential adsorbents for the sustainable management of agricultural wastewaters.
