Removal of diclofenac from aqueous solutions by adsorption on thermo-plasma expanded graphite (original) (raw)
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Adsorption of sodium diclofenac in aqueous medium using graphene oxide nanosheets
Environmental Technology, 2019
In this work, the adsorption of sodium diclofenac (DCF) on graphene oxide nanosheets (GON) was evaluated. GON was synthesized by the modified Hummers method and characterized regarding its composition, morphology, and surface load. It was applied in batch adsorption tests. The process was evaluated from the kinetic, isothermal and thermodynamic properties, and parameters such as adsorbent mass and solution pH were optimized. The best working condition was observed at the natural pH of the solution (6.2) and 0.25 g L-1 adsorbent dosage. The pseudo-first-order and pseudo-second-order models were applied to verify the behavior of the adsorption kinetics, and the adsorption isotherms were also developed at temperatures ranging from 25 to 45 °C. The isotherm models of Langmuir, Freundlich, and Temkim were applied to the equilibrium data. The thermodynamic parameters of enthalpy, entropy, and Gibbs free energy were evaluated to describe the behavior of the adsorptive process. The maximum adsorption capacity of DCF at 25 °C was 128.74 mg g-1 with a removal rate of 74 % in 300 minutes. The process was favourable and spontaneous with adsorptive capacity decreasing with increasing temperature. In addition, an adsorption mechanism was proposed to show the possible bonds that occur between adsorbate and adsorbent and the interactions formed through the influence of pH.
Adsorption characteristics of diclofenac sodium onto graphene nanoplatelets
2020
Adsorption characteristics of diclofenac sodium (DCS) onto graphene nanoplatelets (GNP) were evaluated in this study. Batch adsorption experiments were carried out to study the efficiency of GNP to remove DCS. Optimum conditions such as contact time, adsorbent dosage, the initial concentration of DCS, pH, and temperature were investigated for the maximum removal of DCS. Maximum removal of 99% was observed at 25°C temperature, 3.5 g/L dosage of GNP, pH of 5, 5 mg/L concentration of DCS, and a contact time of 40 min. Moreover, three different isotherm models were applied to study the interactions between molecules of adsorbate and adsorbent. Langmuir isotherm was found to most suitable fit the data with an R2 value of 0.9967 and the Langmuir constant (KL) was found to be 1.0363 L/mg. Kinetic models were also examined, and it was observed that the adsorption process follows pseudo-second-order kinetics with a rate constant K2 = 1.8218 g/mg min. Finally, thermodynamic properties were ca...
DESALINATION AND WATER TREATMENT
Recently, emerging contaminants have been studied with greater attention due to their growing presence in aquatic environments, medications being one of the major pollutants owing to their global consumption. Among the main pharmaceuticals detected, the anti-inflammatory diclofenac sodium (DS) is considered the most ecotoxic and features on the European list of priority substances for monitoring as part of Water Framework Directive 39/2013. Among the water treatment processes available, adsorption is a highly effective technical and economic alternative. As such, this study aimed to assess DS removal efficiency using graphene oxide (GO) as an adsorbent. DS was analyzed using a central composite design, with four factors: diclofenac sodium concentration (DS C of 50 to 450 mg L-1), adsorbent concentration (ADS C of 0.2 to 5 g L-1), contact time (C t of 5 to 45 min) and pH (5 to 9). The results confirmed the modeling of adsorption capacity, adsorbate removal, pseudo-first-order and pseudo-second-order kinetics, intraparticle diffusion, and Langmuir and Freundlich isotherms. DS demonstrated an affinity for adsorption onto GO nanosheets. Maximum adsorption capacity for GO was 669.50 mg g-1 (DS C of 450 mg L-1 , ADS C of 0.2 g L-1 , C t of 34.3 min and pH 5) obtained by duplicate identification batches. The data also supported the creation of an equation that indicates the adsorbent dose needed for total DS removal (100%) from a solution.
Hydrochar-derived adsorbent for the removal of diclofenac from aqueous solution
Nanotechnology for Environmental Engineering
The characteristics and diclofenac adsorption properties of a carbon adsorbent prepared from palm kernel shells were studied. The adsorbent prepared via hydrothermal carbonization followed by an activation in nitrogen flow had a mesoporous structure with homogenous pore distribution and the specific surface area of 131 m2g−1. The Raman spectra showed a formation of graphene or graphite structures in the material during activation with small number of defects based on its ID/IG ratio of about 0.5. The FTIR analysis showed both a qualitative and quantitative decrease in the functional groups of the raw material after activation. The developed adsorbent was found to be effective in the removal of diclofenac with 95% maximum removal at pH 2, adsorbent dose of 15 gL−1 and adsorbate dose of 50 mgL−1. Diclofenac adsorption followed the Langmuir isotherm model with correlation coefficient R2 > 0.98. The adsorption kinetics was explained by the second-order kinetic model with rate constan...
Adsorption of diclofenac sodium from aqueous solutions on commercial activated carbons
DESALINATION AND WATER TREATMENT, 2020
The research presented in this paper aimed to evaluate the possibility of using commercial activated carbons currently used in water treatment plants (WG-12, ROW 08 Supra, F-300) to remove diclofenac sodium, a drug belonging to the group of non-steroidal anti-inflammatory drugs. The kinetics and statics of diclofenac adsorption from solutions of different pH and temperature were studied. The results were described by kinetics equations: pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion model. The highest correlation coefficients were obtained for Elovich (R 2 0.9937-0.9978) and pseudo-second-order models (R 2 0.9885-0.9935). The highest adsorption rate was observed for the activated carbon F-300 (k 2 = 0.0147 h-1), whereas its lowest values were found for ROW 08 Supra (k 2 = 0.0088 h-1). Adsorption statics was analyzed based on solutions with a concentration of 159-1272 mg/L, pH 6, 8, and 10, and temperatures of 20°C, 30°C, and 40°C. Examinations of isotherms of adsorption on activated carbons WG-12, ROW 08 Supra, and F-300 revealed that the lower pH and the higher temperature in the analyzed range, the higher adsorption of the compound tested. The highest adsorption capacities q m were obtained after adsorption from the solution with pH = 6 and were 107.91 mg/g for F-300, 90.41 mg/g for ROW 08, and 88.97 mg/g for WG-12. The adsorption from the solution with pH 10 was much lower: 91.30 mg/g for F-300, 70.79 mg/g for ROW 08, and 58.54 mg/g for WG-12. Increasing the solution temperature from 293 K to 313 K caused an increase in the monolayer capacity from 88.97 to 115.29 mg/g for WG-12 carbon, from 90.41 to 145.45 mg/g for ROW 08 and from 107.91 to 147.88 mg/g for F-300 coal. Diclofenac sodium was best adsorbed on the activated carbon F-300, whereas the poorest adsorption was found for WG-12. The effect of chemical surface structure on the effectiveness of diclofenac sodium adsorption was also observed. The adsorption of sodium diclofenac results from the net force of electrostatic repulsion and attraction forces and hydrogen bonds (H-bonds) and electron donor-acceptor (p-p EDA) interactions. Based on the Langmuir R L and Freundlich 1/n isothermal coefficients, it can be stated that diclofenac sodium adsorption is beneficial for all activated carbons. Among the models used (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) the study results are best described by Langmuir and Freundlich models.
DESALINATION AND WATER TREATMENT, 2019
Tetracycline (TC), a major pollutant in water, has an adverse effect on ecosystem and human health. Thus, it is urgent to remove but still remains a challenging. In this work, a new adsorbent of MnO 2 decorated on sodium hypochlorite treated expanded graphite (MnO 2 /TEG) was developed by an in situ hydrothermal method, which exhibited a highly removal rate of 99.2% to pharmaceutical wastewater treated by flocculation. The structure and morphology of the adsorbent was studied by detailed physical characterization. Meanwhile, the main influencing factors on the adsorption behavior such as pH value, concentration, temperature of the solution, adsorption time, metal oxide species and MnO 2 loading amount were also investigated in detail. It was found that the electrostatic adsorption between Mn 4+ in MnO 2 /TEG and dimethylamino groups in TC molecules played an important role during the adsorption process. These excellent properties proved that the novel composite could be applied to remove TC residues in pharmaceutical wastewater.
Graphene oxide as a new generation adsorbent for the removal of antibiotics from waters
Separation Science and Technology, 2020
The presence of antibiotic molecules in the natural water sources is currently a huge problem due to the development of bacterial resistance. Graphene oxide (GO) has a large potential as a candidate for the applications of water treatment. In this paper, graphene oxide was tested as a new generation adsorbent for the removal of two antibiotics: trimethoprim (TMP) and isoniazid (INH). Both adsorption processes reached the equilibrium in less than one hour. Maximum adsorption capacities were found to be 204.08 mg g-1 for TMP and 13.89 mg g-1 for INH. TMP adsorption on GO was favoured in alkaline medium while the performance of GO for INH adsorption was better in acidic conditions.
ADSORPTIVE REMOVAL OF DOXYCYCLINE FROM AQUEOUS SOLUTION USING GRAPHENE OXIDE/HYDROGEL COMPOSITE
International Journal of Applied pharmaceutics, 2020
Objective: Preparation of novel, safe, and low-cost composite by addition of graphene oxide (GO) to polyvinylpyrrolidone-acrylic acid composite (PVP-AAc) to remove the doxycycline hydrochloride (D) from polluted aquatic environment. Methods: Different concentrations of D were used to study the adsorption process of the antibiotic on the surface of GO/(PVP-AAc) hydrogel composite. The aquatic solution of D was used for studying the adsorption process through a series of different experiments to determine the contact time, adsorbate amount, appropriate temperature, the preferred pH, ionic strength, adsorption kinetics and isotherms on the adsorbent surface of GO/PVP-AAc composite. Fourier transform infrared (FT-IR) spectroscopy and Field-emission scanning electron microscopy (FE-SEM) were used to detect the structure, functional groups and surface morphology of the composite before and after D adsorption. Results: Doxycycline is adsorb on the surface of GO/PVP-AAc hydrogel composite through by physical interactions. The adsorption kinetics correlated to the pseudo-second-order model, contact time studies of D equal to 180 min and the high R 2 value of 0.98 indicates that Langmuir isotherm model better fitted to the data for the removal of D at 15 °C. The results of thermodynamic parameters show that the nature of the adsorption process is physical, exothermic, orderly and spontaneous. The adsorption capacity of D favors the acidic media. When NaCl is added to the solution, the adsorption capacity of D will increase. Conclusion: Graphene oxide/PVP-AAc composite is a novel, worthy and efficient adsorbent for the removal of the doxycycline polluted the water because of its low cost, hydrophilic properties, large surface area and special structure that give impressive dispersible activity in aquatic solutions.
Removal of antibiotic compounds by adsorption using glycerol-based carbon materials
Chemical Engineering Journal, 2016
This study is focused on the synthesis and application of glycerol-based carbon materials (GBCM200, GBCM300 and GBCM350) as adsorbents for the removal of the antibiotic compounds flumequine and tetracycline from aqueous solution. The synthesis enrolled the partial carbonization of a glycerol-sulphuric acid mixture, followed by thermal treatments under inert conditions and further thermal activation under oxidative atmosphere. The textural properties were investigated through N2 adsorption-desorption isotherms, and the presence of oxygenated groups was discussed based on zeta potential and Fourier transform infrared (FTIR) data. The kinetic data revealed that the equilibrium time for flumequine adsorption was achieved within 96 h, while for tetracycline, it was reached after 120 h. Several kinetic models, i.e., pseudo-first order, pseudo-second order, fractional power, Elovich and Weber-Morris models, were applied, finding that the pseudo-second order model was the most suitable for the fitting of the experimental kinetic data. The estimated surface diffusion coefficient values, Ds, of 3.88 and 5.06 x 10-14 m 2 .s-1 , suggests that the pore diffusion is the rate limiting step of the adsorption process. Finally, as it is based on SSE values, Sips model well-fitted the experimental FLQ and TCN adsorption isotherm data, followed by Freundlich equation. The maximum adsorption capacities for flumequine and tetracycline was of 41.5 and 58.2 mg.g-1 by GBCM350 activated carbon.