Jujube stones based highly efficient activated carbon for methylene blue adsorption: Kinetics and isotherms modeling, thermodynamics and mechanism study, optimization via response surface methodology and machine learning approaches (original) (raw)
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Journal Materials and Environmental Science, 2020
Abstract Activated carbon was synthesized from Delonix regia pods by impregnation with zinc chloride. The adsorbent characteristics revealed high surface area and porosities. The adsorption of Methylene Blue (MB) from aqueous solution onto Delonix regia Pod Activated Carbon (DRPAC) was investigated under various experimental conditions in Batch mode of operation. Effects of adsorbent dose, pH, temperature, and contact time were studied. The optimum conditions of adsorption were found to be: adsorbent dose of 0.6 g, pH of 7, Temperature of 30 oC and contact time of 40 minutes. At optimum conditions, removal efficiencies (%) were found to be 88.5, 91.2, 96.5, and 100, while adsorption capacity (qe) was 33.3, 34.3, 36.3 and 37.7 mg/g respectively for the parameters studied. Equilibrium isotherm studies revealed that the adsorption was well described by both the Freundlich and Langmuir models with the Freundlich model exhibiting a better fit (R2= 0.9102). Kinetic studies showed that the adsorption rate was better described by the pseudo second order model (R2= 0.999) as compared to the pseudo first order kinetic model (R2 = 0.969). Thermodynamic parameter estimates showed that MB adsorption on DRPAC is spontaneous, endothermic and feasible. Regeneration and stability of the adsorbent up to five adsorption-desorption cycles was also demonstrated with excellent results. It was concluded that, DRPAC an efficient low-cost adsorbent for the removal of MB from industrial wastewater and hence could generally be used in the treatment of wastewater for colour removal.
Asian Journal of Chemistry, 2013
The removal of dyes from waste effluents is considered as an environmental need because they can be visible and highly toxic even at very low concentration levels 1. Dyes contaminate environment from various industries, like textiles, paper, cosmetics, printing and foods. Dyes can destroy aquatic life because they prevent sunlight from reching water bottom totally. Also dyes may be mutagenic and/or carcinogenic to human 2. Usually, methylene blue is used for cotton and wood. Methylene blue can cause eye damage for human and animals. On inhalation, it may lead to short periods of rapid or difficult breathing; ingestion may cause nausea and methemoglobinemia 3. Many methods are used to remove colour from industrial effluents such as biological biodegradation 4 and adsorption 5. Many previous works studied the removal of methylene blue using different adsorbent such as coffee husks 6 , yellow passion fruit waste 7 , rice husks 8 , banana peel 9 , cereal chaff 10 , spent coffee grounds 11 , orange peel 9 , wheat shells 12 , durian peel 13 , etc. The application of untreated agricultural or plant waste as adsorbents, in addition to its low adsorption efficiency, may lead to additional organic load in the treated effluent in the form of chemical oxygen demand (COD), biological oxygen demand (BOD) and total organic carbon (TOC) due to release
Arabian Journal for Science and Engineering, 2020
Wild carob (WC), an abundant and unused lignocellulosic waste in Algeria, has been used as an inexpensive biosorbent for the elimination of methylene blue (MB) from the aqueous solution and as a precursor for the preparation of a new activated carbon by chemical activation with ZnCl 2 (ACWC). The adsorbent materials were characterized by N 2 physisorption, SEM/ EDX, FTIR spectroscopy and isoelectric point (pHpzc) measurements. The adsorption performance of WC and ACWC was estimated for MB at different adsorption variables, such as solution pH (2-11), MB initial concentrations (25-200 mg L −1), time (0-1500 min), adsorbent dose (0.25-2.00 g L −1), temperature (10-40 °C) and NaCl concentration (0.0-0.5 M). The obtained results indicate that WC has an acidic surface due to the presence of carboxyl and phenol groups that play an important role in the fixation of cationic dye molecules, obtaining a maximum monolayer adsorption capacity of 84 mg g −1 at natural pH (7.5) and 40 °C. However, this adsorption performance was much higher in the case of the ACWC sample (218 mg g −1). From the equilibrium data, the Freundlich, Langmuir, Sips and Redlich-Peterson isotherms parameters of both samples were calculated and compared. For WC, the experimental data fitted well with Redlich-Peterson, Langmuir and Sips isotherm models, while in the case of ACWC they were best represented by the Redlich-Peterson and Sips isotherms. The adsorption kinetics data were found to follow the pseudo-second-order model for WC and the pseudo-first-order model for ACWC. The thermodynamic parameters suggest that, for both materials, the process was endothermic and spontaneous in the range of temperatures studied.
Chemical engineering research & design, 2020
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Adsorption Science & Technology, 2017
A comprehensive study was performed for a thermally treated activated carbon to evaluate the influence of this treatment on the physical and chemical properties of the mineral activated carbon, as well as the adsorption toward phenol and methylene blue. After the heat treatment, surface area decreased and total pore volume diminished about 8.5%, and the total basic groups decreased 18% while the total acid groups increased 8% in comparison with the raw activated carbon. Equilibrium adsorption of phenol and methylene blue was described well with the Freundlich and Langmuir isotherm models, respectively. Adsorption kinetics of phenol and methylene blue was predicted adequately with the empirical pseudo-second-order model, the intraparticle diffusion model, and the homogeneous solid diffusion model, but mass transfer coefficients of the diffusion models help to better understand the adsorption phenomenon. Intraparticle diffusion seems to be the ratecontrolling step in the adsorption process, and heat-treated activated carbon in an inert atmosphere was a better adsorbent for both phenol and methylene blue than raw activated carbon.
Water Science and Technology
Methylene blue (MB) is the cationic dye that is widely used for coloring cotton, wool, and silk. Since MB is harmful to human beings and toxic to microorganisms, there is the need to find cheap and efficient methods for removal of MB from wastewater prior to disposal into natural waters. In the present study, MB adsorption potential of MgO/AC prepared using a sol–gel-thermal deep-coating method was compared with the activated carbon (AC). The central composite design (CCD) as a method of the response surface methodology (RSM) was applied to minimize the number of runs and process optimization. The characterization of the microporous MgO/AC composite showed that the magnesium oxide nanoparticles were successfully coated on the AC and the BET specific surface area of AC and MgO/AC were 1,540 and 1,246 m2/g, respectively. The MB removal efficiency and the maximum adsorption capacity of AC and MgO/AC were 89.6, 97.5% and 571.7, 642.3 mg/g, respectively under optimum operational conditio...
Environmental Nanotechnology, Monitoring & Management, 2020
Three different types of activated carbon were synthesized from tea-waste by chemical activation method using three activating agents-H 3 PO 4 (H-AC), KOH (K-AC) and ZnCl 2 (Z-AC) for analyzing the influence of activating agents on the physicochemical and adsorptive properties of materials. Energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectrometer (FT-IR), field emission scanning electron microscopy (FESEM), Xray diffractometer (XRD), thermogravimetric analyzer (TGA), N 2 gas adsorption-desorption analyzer, and point of zero charge (pH PZC) were employed for the characterization of the synthesized materials. Adsorption capacity of H-AC was found to be higher than those of K-AC and Z-AC, and methylene blue (MB) removal efficiency of H-AC was around 98 % for the adsorbent dose of 0.15 g/L. The greater MB removal capacity of H-AC might be due its higher surface area and micropore volume than those of K-AC and Z-AC. The experimental data of batch equilibrium studies for H-AC and Z-AC fitted well with Freundlich isotherm model whereas MB sorption onto K-AC followed Langmuir isotherm. The adsorption kinetic data for all adsorbents followed pseudo-second order model. Intraparticle diffusion model indicated the influence of both external surface adsorption and intraparticle diffusion on adsorption mechanism.
2016
Physic nut residue is one of bio-wastes which contains enough carbon can be processed further into other products with higher usage and economical value. One of the products is activated carbon which used commonly in chemical industry. Information regarding the kinetics describing mechanism and characteristic of adsorption using physic nut residue-based activated carbon can be obtained through modeling. Model used in this research are Pore-Surface Diffusion Model (PSDM) and Film-Pore Diffusion Model (FPDM) derived based on shrinking core model. This research begins with estimating the value of kf, Ds, and Dp parameters which later will be validated and simulated using various correlations and the model. Variations are done towards three variables: initial aqueous phase concentration (C0), pH value, and adsorbent types. The result shows PSDM is more accurate in representing the mass transfer characteristics of methylene blue adsorption using activated carbon synthesized from physic n...
International Journal of Environmental Science and Technology, 2014
Low-cost activated carbons were prepared by physical activation of bio-waste rice husk. Various physicochemical characterization techniques confirmed the high surface area and oxygen functional groups on the surface. It has been confirmed that activation under humidified carbon dioxide followed by ozonation resulted the highest number of surface functional groups on activated carbon. Nitrogen adsorption-desorption isotherms confirmed the highest surface area (417 m 2 /g), whereas elemental analysis ensured the increasing oxygen content after activation. Temperature-programmed decomposition quantified these surface oxygen functional groups, and it was concluded that ozonation increased both acidic and basic groups. The developed activated carbons were tested during the removal of a model dye methylene blue from aqueous medium in the concentration range 10-30 mg/L. Typical results indicated that adsorption studies are consistent with the Langmuir isotherm model with maximum monolayer adsorption capacity of 28.5 mg/g, and the dimensionless separation factor (R L) values between 0.006 and 0.030 confirmed a favorable adsorption. Methylene blue adsorption followed pseudo-second order kinetics indicating MB was adsorbed onto the surface via chemical interaction.