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The scanning electron microscopy (SEM) image of activated carbon (a) before and (b) after the uptake process
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In this study, activated carbon synthesized from Aloe vera green wastes was used as a sorbent to remove 4-chlorophenol (4-CP) from aqueous solutions. The influence of contact time (0-100 minutes), pH (2-8), adsorbent dosage (1-9 g/l), and initial 4-CP concentration (10-60 mg/l) in batch system was investigated on the sorption. The sorbent was speci...
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Context 1
... q e (mg/g) is the sorption capacity of Aloe vera green waste-based activated carbon, C 0 and C e (mg/l) are the initial and equilibrium adsorbate concentrations, V (l) is the volume of the solution and m (g) is the mass of adsorbent. Chemical composition of activated carbon derived from Aloe vera green waste showed that O, Ca, K, and Mg formed 92.7% of the total weight (wt%) of the sorbent. Other minor compounds included Na (5.92%) and Cl (1.35%). Figures 1 (a) and (b) illustrate the surface morphology of the sorbent before and after the sorption. As seen in figure 1 (a), before the sorption, the surface morphology of activated carbon has uneven cavities and fine open pores. A regular structure and developed pores can be seen after the sorption in figure 1 (b), which shows a smoother surface of activated carbon. The development of pores can be due to the effect of 4-CP that has filled the pores. The sorption data versus contact time for the uptake of 4-CP by Aloe vera green waste-based activated carbon is indicated in figure 2 (a). It can be seen that at first initial adsorption of 4- CP occurred rapidly. Equilibrium was obtained at contact time of 40 minutes (q e = 5.59 mg/g), and then, gradually reached a fixed state during the remaining time of up to 100 minutes. The fast uptake of 4-CP molecules at the beginning of the adsorption time can be due to the availability of large numbers of vacant sites on the sorbent surface. With the increasing of contact time these vacant sites were saturated with 4-CP and adsorption capacity was gradually increased. Similar results were obtained for the removal of 4-CP by various adsorbents. 5,16,18 Zazouli et al. reported that the optimum contact time for removal of 4-CP from aqueous solution by Azolla filiculoides biomass was obtained at 75 minutes. 22 Bilgili showed that the sorption of 4- CP from aqueous media by XAD-4 resin reached equilibrium at contact time of 120 minutes. 15 Therefore, in this study, the contact time of 40 minutes was selected for the subsequent experiments. Kinetic models are suitable for designating the sorption mechanism of 4-CP on the adsorbent surface. In this study, the experimental data was fitted by pseudo-first order and pseudo- second order kinetic models in order to attain a better understanding from the sorption process and the results are presented in table 1. The pseudo-first order kinetic model 24-26 can be illustrated by equation (2): Where q e and q t (mg/g) are the values of 4- CP adsorbed onto the activated carbon surface at equilibrium and at time t (minute), respectively. Moreover, K 1 (1/minute) is the rate constant of the pseudo-first order kinetic model. K 1 and q e were determined from linear plot of ln q − q versus time (minute), which are obtained from the slope and intercept, respectively. The experimental data of 4-CP sorption was also analyzed using pseudo-second order kinetic model. 24,27 This sorption kinetic model can be shown by the following equation: Where q e and q t (mg/g) are similar to the pseudo-first order kinetic model, and K 2 (g/mg. minute) is the rate constant of the pseudo-second order kinetic. K 2 and q e can be obtained from the intercept and slope of against time in equation 3, respectively. Figures 2 (b) and (c) show the pseudo-first order and pseudo-second order kinetic models for the adsorption of 4-CP from aqueous solutions by activated carbon obtained from Aloe vera green waste. The higher liner correlation coefficient (R 2 > 0.98) of the pseudo-second order kinetic model showed that the pseudo-second order kinetic model fitted the experimental data better than other kinetic models described earlier. Ahmed and Theydan showed that the removal of 4-CP from aqueous solution using activated carbon from Albizia lebbeck seed pods followed the pseudo-second order kinetic model. 5 Zazouli et al. also illustrated that the equilibrium data of 4-CP removal using Azolla filiculoides biomass was well described by the pseudo-second orde kinetic model. 22 These results are in agreement with those reported by Tseng and Tseng 28 and Wu et al. 29 for 4-CP adsorption on activated carbons prepared from different agricultural precursors. The solution pH is a substantial parameter in the sorption system . 30 The solution pH has a control effect on the ionization, dissociation, nature, and surface properties of the sorbent. 31 The influence of pH on the removal of 4-CP was investigated and the results are illustrated in figure 3 (a). As can be seen, the increasing of solution pH had a significant effect on the decreasing of 4-CP sorption by activated carbon. This result may be due to change in surface charge of 4-CP molecules and functional groups of the sorbent. The isoelectric point of the natural sorbent was found to be at pH of 11.3. At the lower pH values of the isoelectric point, there is a positive charge on the sorbent surface which will promote reaction with 4-CP. Radhika and Palanivelu reported that at a pH of 2, the adsorbent surface has more positively charged sites, but with the increase in solution pH, the sorption of 4-CP decreases. 32 Thus, the optimum pH for the removal of 4-CP by carbon in this study was chosen as a pH of 2. The effect of different dosages of Aloe vera green waste-based activated carbon was evaluated in an initial 4-CP concentration of 20 mg/l at room temperature and the results are presented in figure 3(b). It was observed that with increasing the adsorbent dosage from 1 g/l to 9 g/l, the adsorption capacity was reduced. The decrease in the sorption value of 4-CP in higher dosages of Aloe vera green waste activated carbon may be due to the unavailability of the pollutant molecules and their inability to cover all the active sites on the adsorbent surface. In other words, a large number of the surface active sites of the adsorbent cannot reach saturation state at high Aloe vera green waste activated carbon dosages. Therefore, a 1 g/l dose of Aloe vera green waste activated carbon was chosen as the optimum dosage for the next stages. Bilgili illustrated that the sorption of 4-CP from aqueous media remained almost constant at sorbent dosages greater than 10 g/l. 15 The influence of initial concentrations of 4-CP on the sorption capacity was investigated and the results are illustrated in figure 4 (a). It is evident that the sorption capacity of activated carbon prepared from Aloe vera green waste rapidly increased with the increasing of 4-CP in the solution. This can be due to accessibility of vacant sites of the adsorbent surface and increase in the driving force of 4-CP including the van der Waals force to the active sites of the adsorbent; this state can occur at higher 4-CP concentrations. When the sorption process reaches an equilibrium state, the study of adsorption isotherms is necessary in order to explain the distribution of adsorbate molecules between liquid and solid phases. Moreover, the isotherms can provide information about the heterogeneity and homogeneity of the adsorbent surface. 33 In this study, the experimental data were analyzed by Langmuir, Freundlich, and Tempkin isotherms in initial concentration of 10-100 mg/l at contact time of 12 hours and the results are presented in table 2. The Langmuir isotherm assumes that monolayer uptake occurs at binding sites with homogenous energy levels. 13 This isotherm model predicts the maximum sorption capacity of 4-CP on the homogenous surface of Aloe vera green waste-based activated carbon. The Langmuir isotherm can be linearized using equation (4): Where C e (mg/l) is the equilibrium concentration of 4-CP, q e (mg/g) the sorption capacity of Aloe vera green waste activated carbon in during the equilibrium time. Q m (maximum adsorption capacity, mg/g) and b (the Langmuir constant, l/mg) are obtained from the slope and intercept of linear plots of C e /q e versus C e , respectively. The essential property of the Langmuir isotherm model is a dimensionless constant separation factor, R L , or ...
Context 2
... q e (mg/g) is the sorption capacity of Aloe vera green waste-based activated carbon, C 0 and C e (mg/l) are the initial and equilibrium adsorbate concentrations, V (l) is the volume of the solution and m (g) is the mass of adsorbent. Chemical composition of activated carbon derived from Aloe vera green waste showed that O, Ca, K, and Mg formed 92.7% of the total weight (wt%) of the sorbent. Other minor compounds included Na (5.92%) and Cl (1.35%). Figures 1 (a) and (b) illustrate the surface morphology of the sorbent before and after the sorption. As seen in figure 1 (a), before the sorption, the surface morphology of activated carbon has uneven cavities and fine open pores. A regular structure and developed pores can be seen after the sorption in figure 1 (b), which shows a smoother surface of activated carbon. The development of pores can be due to the effect of 4-CP that has filled the pores. The sorption data versus contact time for the uptake of 4-CP by Aloe vera green waste-based activated carbon is indicated in figure 2 (a). It can be seen that at first initial adsorption of 4- CP occurred rapidly. Equilibrium was obtained at contact time of 40 minutes (q e = 5.59 mg/g), and then, gradually reached a fixed state during the remaining time of up to 100 minutes. The fast uptake of 4-CP molecules at the beginning of the adsorption time can be due to the availability of large numbers of vacant sites on the sorbent surface. With the increasing of contact time these vacant sites were saturated with 4-CP and adsorption capacity was gradually increased. Similar results were obtained for the removal of 4-CP by various adsorbents. 5,16,18 Zazouli et al. reported that the optimum contact time for removal of 4-CP from aqueous solution by Azolla filiculoides biomass was obtained at 75 minutes. 22 Bilgili showed that the sorption of 4- CP from aqueous media by XAD-4 resin reached equilibrium at contact time of 120 minutes. 15 Therefore, in this study, the contact time of 40 minutes was selected for the subsequent experiments. Kinetic models are suitable for designating the sorption mechanism of 4-CP on the adsorbent surface. In this study, the experimental data was fitted by pseudo-first order and pseudo- second order kinetic models in order to attain a better understanding from the sorption process and the results are presented in table 1. The pseudo-first order kinetic model 24-26 can be illustrated by equation (2): Where q e and q t (mg/g) are the values of 4- CP adsorbed onto the activated carbon surface at equilibrium and at time t (minute), respectively. Moreover, K 1 (1/minute) is the rate constant of the pseudo-first order kinetic model. K 1 and q e were determined from linear plot of ln q − q versus time (minute), which are obtained from the slope and intercept, respectively. The experimental data of 4-CP sorption was also analyzed using pseudo-second order kinetic model. 24,27 This sorption kinetic model can be shown by the following equation: Where q e and q t (mg/g) are similar to the pseudo-first order kinetic model, and K 2 (g/mg. minute) is the rate constant of the pseudo-second order kinetic. K 2 and q e can be obtained from the intercept and slope of against time in equation 3, respectively. Figures 2 (b) and (c) show the pseudo-first order and pseudo-second order kinetic models for the adsorption of 4-CP from aqueous solutions by activated carbon obtained from Aloe vera green waste. The higher liner correlation coefficient (R 2 > 0.98) of the pseudo-second order kinetic model showed that the pseudo-second order kinetic model fitted the experimental data better than other kinetic models described earlier. Ahmed and Theydan showed that the removal of 4-CP from aqueous solution using activated carbon from Albizia lebbeck seed pods followed the pseudo-second order kinetic model. 5 Zazouli et al. also illustrated that the equilibrium data of 4-CP removal using Azolla filiculoides biomass was well described by the pseudo-second orde kinetic model. 22 These results are in agreement with those reported by Tseng and Tseng 28 and Wu et al. 29 for 4-CP adsorption on activated carbons prepared from different agricultural precursors. The solution pH is a substantial parameter in the sorption system . 30 The solution pH has a control effect on the ionization, dissociation, nature, and surface properties of the sorbent. 31 The influence of pH on the removal of 4-CP was investigated and the results are illustrated in figure 3 (a). As can be seen, the increasing of solution pH had a significant effect on the decreasing of 4-CP sorption by activated carbon. This result may be due to change in surface charge of 4-CP molecules and functional groups of the sorbent. The isoelectric point of the natural sorbent was found to be at pH of 11.3. At the lower pH values of the isoelectric point, there is a positive charge on the sorbent surface which will promote reaction with 4-CP. Radhika and Palanivelu reported that at a pH of 2, the adsorbent surface has more positively charged sites, but with the increase in solution pH, the sorption of 4-CP decreases. 32 Thus, the optimum pH for the removal of 4-CP by carbon in this study was chosen as a pH of 2. The effect of different dosages of Aloe vera green waste-based activated carbon was evaluated in an initial 4-CP concentration of 20 mg/l at room temperature and the results are presented in figure 3(b). It was observed that with increasing the adsorbent dosage from 1 g/l to 9 g/l, the adsorption capacity was reduced. The decrease in the sorption value of 4-CP in higher dosages of Aloe vera green waste activated carbon may be due to the unavailability of the pollutant molecules and their inability to cover all the active sites on the adsorbent surface. In other words, a large number of the surface active sites of the adsorbent cannot reach saturation state at high Aloe vera green waste activated carbon dosages. Therefore, a 1 g/l dose of Aloe vera green waste activated carbon was chosen as the optimum dosage for the next stages. Bilgili illustrated that the sorption of 4-CP from aqueous media remained almost constant at sorbent dosages greater than 10 g/l. 15 The influence of initial concentrations of 4-CP on the sorption capacity was investigated and the results are illustrated in figure 4 (a). It is evident that the sorption capacity of activated carbon prepared from Aloe vera green waste rapidly increased with the increasing of 4-CP in the solution. This can be due to accessibility of vacant sites of the adsorbent surface and increase in the driving force of 4-CP including the van der Waals force to the active sites of the adsorbent; this state can occur at higher 4-CP concentrations. When the sorption process reaches an equilibrium state, the study of adsorption isotherms is necessary in order to explain the distribution of adsorbate molecules between liquid and solid phases. Moreover, the isotherms can provide information about the heterogeneity and homogeneity of the adsorbent surface. 33 In this study, the experimental data were analyzed by Langmuir, Freundlich, and Tempkin isotherms in initial concentration of 10-100 mg/l at contact time of 12 hours and the results are presented in table 2. The Langmuir isotherm assumes that monolayer uptake occurs at binding sites with homogenous energy levels. 13 This isotherm model predicts the maximum sorption capacity of 4-CP on the homogenous surface of Aloe vera green waste-based activated carbon. The Langmuir isotherm can be linearized using equation (4): Where C e (mg/l) is the equilibrium concentration of 4-CP, q e (mg/g) the sorption capacity of Aloe vera green waste activated carbon in during the equilibrium time. Q m (maximum adsorption capacity, mg/g) and b (the Langmuir constant, l/mg) are obtained from the slope and intercept of linear plots of C e /q e versus C e , respectively. The essential property of the Langmuir isotherm model is a dimensionless constant separation factor, R L , or ...
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... The microscopic examinations revealed distinct variations in the textural characteristics of the CCG and ACG samples compared to the CG sample. The images demonstrated the degree of irregularities on the surfaces of CCG and ACG, which exhibited a greater level of roughness, a highly porous structure, and numerous voids when compared to the raw material from SCG [69]. ...
... The microscopic examinations revealed distinct variations in the textural characteristics of the CCG and ACG samples compared to the CG sample. The images demonstrated the degree of irregularities on the surfaces of CCG and ACG, which exhibited a greater level of roughness, a highly porous structure, and numerous voids when compared to the raw material from SCG [69]. The porous structures of carbon materials have a substantial impact on their ability to adsorb CO2. ...
Carbon dioxide (CO2) capture has been identified as a potential technology for reducing the an-thropic emissions of greenhouse gases, particularly in post-combustion processes. The develop-ment of adsorbents for carbon capture and storage is expanding at a rapid rate. This article pre-sents a novel sustainable synthesis method for the production of chitosan/activated carbon CO2 adsorbents. Chitosan is a biopolymer that is naturally abundant and contains amino groups (–NH2), which are required for the selective adsorption of CO2. Spent coffee grounds have been considered as a potential feedstock for the synthesis of activated coffee grounds through carboni-zation and chemical activation. The chitosan/activated coffee ground composite microspheres were created using the emulsion cross-linking method with epichlorohydrin. The effects of the amount of chitosan (15, 20, and 25 g), activated coffee ground (10, 20, 30, and 40%w/w), and epichlorohy-drin (2, 3, 4, 5, 6, 7 and 8 g) were examined. The CO2 capture potential of the composite beads is superior to that of the neat biopolymer beads. The CO2 adsorbed of synthesized materials at a standard temperature and pressure is improved by increasing the quantity of activated coffee ground and epichlorohydrin. These findings suggest that the novel composite bead has the poten-tial to be applied in CO2 separation applications.
... The energy-dispersive X-ray spectroscopy (EDX) analysis presented in Fig. 5(c) confirms the presence of carbon and oxygen elements on the (Low et al., 2008;Omidi-Khaniabadi et al., 2015;Wang et al., 2008a). Offers a synopsis of the elemental concentrations found on the surface of AC-Ws before the adsorption of MG and SAF, as determined through EDX and SEM analysis. ...
... The experimental solution was determined by diluting the dye stock solution inaccurate volume of industrial wastewater needed for initial concentrations. The removal experiments were conducted with parameters such as dye's initial concentration was estimated by contacting 0.1 g of nano-biosorbent with 100 mL of dye's solutions of different initial concentrations ranging from 5 to 100 mg/L for CR and from 5 to 60 mg/L for XO and agitation speed of 200 rpm were maintained 4 . The effect of the initial pH on the adsorption of the two dyes adsorbed was obtained by agitating 0.1 g of Fe 3 O 4 nano-sorbents in a series of bottles containing 100 mL of spiked wastewater solution of initial concentration 60 mg/L for CR and 35 mg/L for XO at different pH from 2.0 to 10.0 by using diluted solutions of HCl and NaOH. ...
The majority of environmental researchers are becoming increasingly concerned with the manufacture of inexpensive adsorbents for the detoxification of industrial effluents. To address one of the significant and well-known pollution issues with certain drains that act as hotspots and contribute to coastal pollution in Alexandria, this study aims to develop an economical, ecologically friendly sorbent. This study assessed the efficacy of a biomass-coated magnetic composite and a magnetic active adsorbent for the removal of two dyes from an industrially contaminated sewer using a wetland plant (Phragmites australis). Using magnetic biosorbent, the biosorption of Xylenol orange and Congo red ions from polluted drain discharge in Abu Qir Bay was evaluated in the current study. Using scanning electron microscopy imaging and Fourier transform infra-red analysis; the surface function and morphology of the nano-biosorbent were examined. At room temperature, the effects of initial dye concentration, pH, contact time, and nano-biosorbent concentration have all been investigated. The greatest percentages that nano-biosorbent can remove from Congo red and Xylenol orange are 97% and 47%, respectively. The removal of the initial Congo red concentration varied from 42 to 97%, while the removal of the initial Xylenol orange concentration varied from 30 to 47%. The adsorption capacity was shown to be strongly pH-dependent; capacity dose as pH value increased, with pH 10 being the ideal pH for Congo red and pH 6 being the ideal pH value for Xylenol orange. The adsorption capacity for Congo red varied between 0.96 and 3.36 and the adsorption capacity for Xylenol orange varied between 0.18 and 17.58. The removal capacity decreased from 3.36 to 0.96 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L for Congo red, in case of Xylenol orange, the removal capacity increased from 0.18 to 17.58 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L. The removal capacity of Congo red increases quickly with time and varied from 1.66 to 1.88 of contact time; while the removal capacity of Xylenol orange varied between 3.08 and 4.62 of contact time. For the dyes under study, kinetics and adsorption equilibrium were examined. Within 180 min, the equilibrium was attained because to the quick adsorption process. For Congo red and Xylenol orange, the highest adsorption capacities were 3.36 and 17.58 mg g⁻¹, respectively. The equilibrium data were assessed using a number of isotherm models, including Langmuir, Freundlich, BET, and Tempkin, while the kinetic data were examined using a variety of kinetic models, including pseudo-first- and pseudo-second-order equations. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data.
... To confirm that the porosity comes from the activated carbon, we also analyzed its structure with SEM, as presented in Fig. 1c. We observed a highly porous structure, typical for activated carbons [31][32][33][34]. Such high porosity ensured superior adsorptive properties and high specific surface area. ...
Microbiologically contaminated water is a major health hazard worldwide. Where state-of-the-art solutions fail, nanomaterials come to the rescue with their multitasking features. Our study reports an excellent dual-mode action of novel hybrid nanocomposite filtration beds that combine antimicrobial with photocatalytic features. The activated carbon (C) was used as a substrate for in situ surface decoration with graphene oxide (GO) and bioactive TiO2/Ag nanocomposite particles (NCP) via a zero-waste one-pot sol-gel approach. Obtained C/GO/NCP and C/NCP hybrid nanocomposites were extensively evaluated for their morphology, structure, physicochemical and optical properties. The ability to decompose model methylene blue (MB) dye revealed their high photocatalytic efficiency. Further studies have shown the high potential of carbon-supported nanocomposites in eliminating model and waterborne bacteria cells under static and close-to-real dynamic filtration conditions. After filtration, hybrid nanocomposites eliminated up to 100% of accumulated bacteria cells, which confirmed their self-purifying potential. Finally, we recovered the beneficial properties of developed nanocomposites with low-temperature regeneration. Collectively, we proved the possibility of obtaining nanocomposite filtration beds with high potential in eliminating microbiological contamination, self-disinfection ability, and the possibility of recycling with minimal maintenance effort. Our study brings nanotechnology much closer to practical application in the water maintenance industry.
... On increasing the electrolyte concentration (Ca 2+ ions) in the dye solution from 25 to 100 mg/L, the adsorption capacity decreased partially from 39.55 mg g − 1 to 32.83 mg g − 1 . This may be explained due to the blockage of the active sites of the montmorillonite at high salt concentrations [127,128]. ...
Clays are naturally occurring environment-friendly materials possessing high specific surface area and good cation exchange capacity. Montmorillonite, one of the widely available clays, is known for its accumulative capacity for water-soluble hazardous and toxic dyes on the surface. This can be further modified by introducing inorganic and/or organic species into the interlayer space of the clay with simultaneous alteration in the selectivity and the mode of montmorillonite-dye interactions. The clay surface can be activated for increased interactions by treating with acid and/or base, or by functionalization with select additives. In this work, the use of natural and modified montmorillonites as selective adsorbents for water-soluble dyes is reviewed giving an insight into the theoretical basis of the interactions and the experimental findings based on the application of the popular isotherm and kinetic models. The basic objective is to consolidate the current understanding of the clay-dye interactions from the mechanisms of the interactions.
... It has been used to treat BCG-containing wastewaters ( Biglari et al., 2018 ;Özdemir et al., 2015 ). This is on account of adsorbent's high surface area, high dye uptake and process simplicity while the major drawback in the use of adsorption method is the high cost of the adsorbent (which is usually commercial activated carbon) and the difficulty in its regeneration ( Basiri et al., 2015 ;Omidi et al., 2015 ;Cheng et al., 2015 ). However, some local materials (and waste products in some cases) have been modified and used as activated carbon with varying degrees of success. ...
Genetic algorithm (GA) assisted optimization was used in the adsorptive removal of bromocresol green (BCG) from solution. The adsorbent was acid-functionalized corn cob (AFCC). The properties of the adsorbent were investigated via instrumental analysis involving Fourier Transform Infra-Red (FTIR) and Scanning electron microscopy (SEM). Non-linear modeling involving various degrees of isotherm models were used in the isotherm study. Adaptive neuro-fuzzy inference systems (ANFIS), response surface methodology (RSM), and artificial neural network (ANN) were used to model the BCG removal. The result of the instrumental analysis showed that the properties of the AFCC were enhanced after the acid carbonization process with a surface area of 903.7m²/g. The modeling and predictive adeptness of the ANFIS, RSM, and ANN was very significant with correlation coefficient (R²) of 0.9984, 0.9865, and 0.9979 with root mean square error (RMSE) of 0.00308, 0.00898, and 0.00351 respectively. Validation of the models’ optimization indicated maximum adsorption capacities of 38.04, 34.41, and 41.94 mg/g for RSM-GA, ANN-GA, and ANFIS-GA, respectively. Freundlich, Khan, and Marczewski-Jaroniec isotherms best described the adsorption isotherm for two-term, three-term, and four-term isotherm modeling respectively. Calculated values of Gibbs free energy change (∆Gmax= -7.55 KJ/mol), enthalpy change (∆H=35.84 KJ/mol), and entropy change (∆S=130.20 Jmol⁻¹K⁻¹) indicated the adsorption process was spontaneous, endothermic and with increased randomness respectively. The study showed that the low-cost AFCC obtained from agro-waste has desirable adsorbent properties for the treatment of BCG polluted wastewater.
... Due to the mass transfer process and physicochemical properties of adsorption, kinetic studies are used to evaluate the adsorption performance. Given most kinetics models for adsorption are pseudo-first-order and pseudosecond-order models 25,26 , The formula for the pseudo-first-order relation is as follows 27, 28 : ...
Introduction: Nitrophenol compounds are toxic compounds found in industrial wastewaters. 2,4-dinitrophenol is the most dangerous compound among phenolic compounds. The aim of this study was to evaluate the removal of 2,4-DNP from wastewater by microwaved dried sludge adsorbent.
Materials and Methods: The results of 2,4-DNP removal were discontinuously obtained by the high performance liquid chromatography (HPLC) at a wavelength of 360 nm with various effective factors, such as contact time, pH, initial concentration of 2,4-DNP, and microwaved sludge dose. Finally, the results were analyzed using the kinetics and isotherm models. The equilibrium time was obtained 120 min. The maximum removal rate was obtained at pH 7.
Results: The findings indicated that the removal efficiency increased by increasing the adsorbent dose and decreasing the 2,4-DNP concentration. It was revealed that the removal of 2,4-DNP by microwaved sludge was 86%. The correlation coefficient value of linear and non-linear regression showed that kinetic studies follow the pseudo-second order model and isotherm studies follow the Freundlich isotherm model. The adsorption method relied entirely on pH and affected the adsorbent area attributes, ionization rate, and Delete percentage. When the pH was high, there was competition for the adsorption sites between hydroxide ions (OH) and 2,4-DNP molecules. At first, the adsorption process was high speed and gradually reached a stable level, because after a while, the adsorption sites become saturated.
Conclusion: As the absorbent dose increases, the efficiency of the adsorption process increases, because larger amounts of adsorbent cause higher adsorption places.
... Before sorption, the surface morphology of activated carbon had uneven cavities and irregular open pores, but upon adsorption (drugs) the pores become regular and smoother. While working on adsorption of 4-chlorophenol from aqueous solution using activated carbon synthesized from Aloe Vera green wastes, [20] reported similar micrographs after SEM characterization. ...
The presence of pharmaceutical residues in discharges that end up in rivers is a growing concern for the disruption of aquatic ecosystems and human health. The risk of exposure to these medical wastes becomes greater because they are not biodegradable even after sewage treatment. This study aimed to remove trimethoprim (antibiotic), paracetamol (painkiller), and nevirapine (anti-retroviral) from wastewater using activated carbon made from rice husks, an agricultural waste that was investigated as a potential adsorbent. The instrument used for analysis was a liquid chromatography-tandem mass spectrometer (LC-MS/MS). The powdered carbon of rice husks was carbonated at a temperature of 500oC and then activated by phosphoric acid to increase its porosity. After activation, it was successfully characterized by the use of Scanning electron microscopy which showed irregular cavities with open fine pores. Fourier transform infrared showed different functional groups which determined adsorbent- adsorbate interactions while X-ray diffraction revealed amorphous particle arrangement. The effects of the adsorbent dose, contact time, pH, and initial drug concentration were studied. Freundlich and Langmuir's isotherms were used in the evaluation of adsorption phenomena. Thus, obtained results showed that rice husks activated carbon is an effective adsorbent.
... These organic pollutants are discharged to the aquatic environment as polluted and colored waters without any treatment because the conventional treatment methods are not effective. The colored polluted effluents are considered one of the most serious environmental issues in the world, due to their toxicity and carcinogenicity in addition to allergic dermatitis, skin irritation, cancer, and mutation in humans, especially in developing countries (Omidi-Khaniabadi et al., 2015and Basiri et al, 2015, Somasekhara et al., 2012. Congo Red (CR), anionic dye, is the sodium salt of 3,3´-([1,1´-biphenyl]-4,4´-diyl)bis [4aminonaphthalene-1-sulphonic acid MW= 696.665] the molecular structure of CR has been shown in Fig. 1. ...
The production of low-cost adsorbents for the detoxification of industrial effluents has been a growing concern for most environmental researchers. In this study, a magnetic active adsorbent and biomass (Phragmites australis) coated magnetic composite was synthesized and evaluated their effectiveness for the removal of two dyes from industrial polluted drain. In the present study, the biosorption of Congo red and xylenol orange ions from polluted drain discharge in Abu Qir Bay was determined using magnetic biosorbent. The surface function and morphology of the nano-biosorbent were studied by Fourier Transform Infrared analysis and scanning electron microscope imaging. The effect of initial dye concentration, pH, contact time, and concentration of nano-biosorbent has been studied at room temperature.
The initial concentration increases as the absorption capacity of Congo red and Xylenol orange increase, especially for an initial concentration lower than 60 and 35 m/L for the two dyes respectively. Maximum percentage removal of Congo red and Xylenol orange by nano biosorbent is 77 and 47 % respectively. A strong dependence of the adsorption capacity on pH was observed, the capacity increase as pH value increase, and the optimum pH value is pH 10 for Congo red and pH 6 for Xylenol orange. Kinetics and adsorption equilibrium were studied for the studied dyes. The adsorption process was fast and the equilibrium was reached within 180 min. The maximum adsorption capacities were 1.88 and 4.62 mg g⁻¹ for Congo red and Xylenol orange respectively. The kinetic data were analyzed using various kinetic models – pseudo-first-order equation, pseudo-second-order equation, and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, BET, and Tempkin. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data.
... The densified nature of the adsorbent with complete coverage of the porous honeycomb structure confirmed the phenol binding to the adsorbent surface. The micrograph also showed a uniform coverage of the active sites by the phenol molecules, which indicated the energetically homogenous nature of the activated-carbon glass beads [39]. The SEM image for the spent adsorbent (Figure 7b) showed the successful adsorption of the phenol molecules on the activated-carbon-coated glass beads. ...
... The densified nature of the adsorbent with complete coverage of the porous honeycomb structure confirmed the phenol binding to the adsorbent surface. The micrograph also showed a uniform coverage of the active sites by the phenol molecules, which indicated the energetically homogenous nature of the activated-carbon glass beads [39]. Figure 7c depicts the regenerated surface of the activated-carbon-coated glass beads. ...
A liquid-solid circulating fluidized bed (LSCFB) helps to overcome the shortcomings of conventional fluidized beds by using a particle separation and return system as an integral part of the overall reactor configuration. Batch adsorption experiments were carried out for the removal of phenol from a synthetically prepared solution using fresh activated-carbon-coated glass beads. The morphological features and surface chemistry of the adsorbent were analyzed via SEM and FTIR techniques. The adsorbent dosage, contact time and temperature were varied along with solution pH to assess their effects on the adsorbent performance for phenol removal. Isotherm modeling showed that the phenol removal using the activated-carbon glass beads followed the Langmuir model. Effectively, it was observed at an adsorbent loading of 2.5 g/150 mL of feed volume and a contact time of 3 h produced an 80% efficiency in the batch study. Furthermore, on scaling it up to the column, the desired 98% phenol-removal efficiency was obtained with an adsorbent dosage of 250 g and contact time of 25 min. Adsorbent regeneration using 5% (v/v) ethanol showed a 64% desorption of phenol from the sorbent within 20 min in the LSCFB.
