Kinetic, thermodynamics and equilibrium studies on the removal of Congo red dye using activated teak leaf powder (original) (raw)
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Adsorption Studies of Basic Dyes Onto Teak (Tectona Grandis) Leaf Powder
Journal of Urban and Environmental Engineering, 2015
In this study, the adsorption potential of Teak (Tectona grandis) leaf powder (TLP) to remove Methylene blue (MB) and Malachite Green (MG) dye molecules from aqueous solution was investigated. Batch experiments were conducted to evaluate the influence of operational parameters such as, pH (2-9), adsorbent dosage (1-7 g/L), contact time (15-150 minutes) and initial dye concentration (20-120 mg/L) at stirring speed of 150 rpm, on the adsorption of MB and MG on TLP. The maximum removal efficiency of 98.4% and 95.1% was achieved for MB and MG dye, respectively. The experimental equilibrium data were analyzed using Langmuir, Freundlich and Temkin isotherms and it was found that it fitted well to the Freundlich Isotherm model. The surface structure and morphology of the adsorbent was characterized using Scanning electron microscopy (SEM) and the presence of functional groups and its interaction with the dye molecules were analyzed using Fourier transform infrared (FTIR). Based on the inve...
DESALINATION AND WATER TREATMENT
The removal of Congo red dye from aqueous solutions by adsorption reaction onto three distinct adsorbents: graphene oxide (GO), graphene oxide-grafted-3,3'-diaminobenzidine (GO/ DAB), and GO/DAB-grafted-ethylenediaminetetraacetic acid (GO/DAB/EDTA) was investigated in batch experiments. The study of the effects of pH and contacting time on adsorption systems is the first step in optimizing them. The results revealed that depending on the type of adsorbent, the optimum pH values and periods differed. The Congo red (CR) dye adsorptions onto the investigated adsorbents GO, GO/DAB, and GO/DAB/EDTA required pH (3.0, 7.0, and 5.0, respectively) and time (60, 30, and 45 min). The fundamental adsorption properties of the dye were evaluated using adsorption equilibrium isotherms, namely the Langmuir, Freundlich, and Dubinin-Radushkevich models. The maximum adsorption values (q max) were calculated using the Langmuir isotherm results, and they were 1,250; 1,428.5 and 1,438.1 mg/g for the adsorption of CR dye onto adsorbents GO, GO/DAB, and GO/DAB/EDTA, respectively, and these results proved the preference for prepared GO-derivatives over GO. The kinetic models, namely pseudo-first-order and pseudo-second-order, were employed to understand the mechanism of the adsorption process, and they fitted very well with the pseudo-second-order kinetic model, which relies on the assumption that chemisorption may be the rate-limiting step. This study reveals that the presence of functional groups and active sites on the studied adsorbent contributed to its high affinity for CR dye adsorption. As a result, they can be used as efficient and cost-effective dye adsorbents in industrial effluent. Thermodynamic parameters including enthalpy ΔH°, entropy ΔS°, free energy ΔG°, and activation energy E a of the adsorption process were calculated and used to interpret the results, which revealed that the adsorption systems were a spontaneous and endothermic process for GO and its composites. Also, low activation energy values (E a < 40 kJ/mol) were characteristics of the physisorption mechanism and diffusion-controlled process.
Removal of Congo Red from Aqueous Solutions by Spent Black Tea as Adsorbent
Journal of Water Chemistry and Technology, 2018
Herein we present spent black tea as an adsorbent for the removal of Congo red dye from aque ous solutions. The effects of various parameters such as pH, time, temperature, adsorbent dosage and adsorbate dosage on dye adsorption were investigated. Batch experiments were conducted using different amount of adsorbent material (2.5-1000 mg) at varying amounts of adsorbate (5-500 mg/L) at 35°C and different pH (1-13). A maximum dye removal of >80% was achieved with an adsorbent dose of 100 mg, adsorbate concentration of 5 mg/L under pH range of 6 within 5 min at room temperature. The experi mental data were modeled by Langmuir, Freundlich and Temkin isotherms and conforms to both Lang muir and Freundlich isotherms but not to Temkin isotherm. The proposed spent black tea can be effec tively used as a low cost adsorbent for the removal of Congo red dye.
Journal of Environmental Management, 2004
In the present work, the leaves of Azadirachta indica (locally known as the Neem tree) in the form of a powder were investigated as a biosorbent of dyes taking aqueous Congo Red solution as a model system. The sorbent was made from mature Neem leaves and was investigated in a batch reactor under variable system parameters such as concentration of the aqueous dye solution, agitation time, adsorbent amount, pH, and temperature. An amount of 0.6 g of the Neem leaf powder (NLP) per litre could remove 52.0-99.0% of the dye from an aqueous solution of concentration 2.87 £ 10 22 mmol l 21 with the agitation time increasing from 60 to 300 min. The interactions were tested with respect to both pseudo first-order and second-order reaction kinetics; the latter was found to be more suitable. Considerable intra-particle diffusion was found to occur simultaneously. The sorption process was in conformity with Langmuir and Freundlich isotherms yielding values of the adsorption coefficients in the following ranges: Freundlich n: 0.12 -0.19, K f : 0.1039-0.2648 L g 21 ; Langmuir q m : 41.24 -128.26 g kg 21 , b : 443.3-1898.0 l mmol 21 , which supported favourable adsorption. The Langmuir monolayer capacity ðq m Þ was high and the values of the coefficient b indicated the equilibrium, dye þ NLP ¼ dye· · ·NLP being shifted overwhelmingly towards adsorption. Thermodynamically, the sorption process was exothermic with an average heat of adsorption of 212.75 kJ mol 21 . The spontaneity of the sorption process was also confirmed by the favourable values of Gibbs energy (mean values: 2 1.09 to 21.81 kJ mol 21 ) and entropy of adsorption (range: 2 18.97 to 2 56.32 J mol 21 K 21 ). The results point to the effectiveness of the Neem leaf powder as a biosorbent for removing dyes like Congo Red from water. q
In the present study, spent tea leaves (STL) were used as a new non-conventional and low-cost adsor-bent for the cationic dye (methylene blue) adsorption in a batch process at 30 • C. Equilibrium sorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Fre-undlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to the Langmuir isotherm and the monolayer adsorption capacity was found to be 300.052 mg/g at 30 • C. The kinetic data obtained at different initial concentrations were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The results revealed that the spent tea leaves, being waste, have the potential to be used as a low-cost adsorbent for the removal of methylene blue from aqueous solutions.
Journal of Water Supply: Research and Technology-Aqua
The present research is based on the removal of Brilliant Green (BG) dye from its aqueous solution. Used-tea-powder (UTP) was used as a potential adsorbent to remove BG from aqueous solution. Pore morphology, surface properties, crystalline nature and thermal stability of UTP were assessed by using SEM, FTIR, XRD and TGA analysis. The optimized working conditions were found to be pH 6, UTP dose 100 mg, adsorption time 60 min and BG concentration 100 mg L−1. The qmax obtained from the Langmuir model was 101.01 mg g−1 showing the utility of UTP in dye removal. The breakthrough volume and efficiency of the column were evaluated through column adsorption studies in fixed-bed mode. It was found that the pseudo-second-order kinetics model was followed as evaluated by the correlation studies. The calculated thermodynamic parameters showed that the adsorption process was feasible, exothermic and spontaneous.
Orbital - The Electronic Journal of Chemistry, 2016
Vigna unguiculata seed husk powder has been investigated as low cost adsorbent for the removal of hazardous chemicals like Congo Red (CR) dye from aqueous solution. Various parameters such as effect of contact time, initial CR dye concentration, adsorbent dose, effect of pH, zero-point pH were studied. Batch adsorption technique was employed to optimize the process parameter. The result indicated that, the percentage adsorption of Congo Red increased with increase in contact time, dose of adsorbent and initial concentration of Congo Red and decreased with addition of salt. The adsorption of Congo Red was 78% at the optimum pH of 6. Adsorption equilibrium was found to be reached in 24 h for 5 to 25 g/50 mL Congo red concentrations. The Langmuir and Freundlich isotherm models were found to provide an excellent fitting of the adsorption data. The adsorption of CR follows Second order rate kinetics. Thermodynamic parameter (ΔG o) showed that it was an exothermic process. This adsorbent was found to be effective and economically attractive.
Removal of Congo Red Dye from Aqueous Solution by Date Palm Leaf Base
American Journal of Applied Sciences, 2014
Removal of dyes from wastewater is important for industry and environmental protection. The adsorption technique, using biomass is attractive method for environmental and economical reasons. This study studies removal of Congo Red dye (CR) from aqueous solutions by adsorption using date palm Leaf Base (LB). The adsorption of congo red dye CR onto LB has been examined in aqueous solution by considering the influence of temperature up to 60°C and pH on the percentage removal of CR. The results showed that the percentage removal of CR increased with increasing temperature and decreased with increasing pH. The Langmuir and Freundlich models have been applied to describe the equilibrium data and the thermodynamic parameters, Gibbs free energy ∆G°, enthalpy change ∆H° and entropy ∆S°, have been determined. The negative value of ∆H suggests that adsorption of CR by the date palm leaf base is exothermic. The positive values of ∆G° at all studied temperatures indicate that CR adsorption is a unspontaneous process. LB is a promising adsorbent for the removal of CR from aqueous solution over a range of concentrations.
DESALINATION AND WATER TREATMENT
Potato peels (PP) and peanut hulls (PH) have been used as biosorbents to remove Methylene Blue (MB) from aqueous solution. By using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X ray diffraction (XRD) analysis, PP and PH have been characterized. FTIR analysis confirmed the presence of carboxyl and phenolic hydroxyl groups which constitute the major adsorption sites onto PP and PH. SEM micro photographs indicated the presence of tiny pores on the adsorbent surface responsible for sorption process. XRD showed the presence of crystalline structures in both adsorbents. The effect of different parameters on adsorption was investigated, and conditions were optimized. The equilibrium and kinetics data obtained were analyzed using different models. The adsorption data confirmed second order kinetics and Langmuir Isotherm to be the best fit model for both adsorbents. Thermodynamic studies showed that the sorption process of MB was endothermic and more effective at lower temperatures. The results demonstrated that PH powder has a sufficient potential as an efficient adsorbent material for the removal of basic dyes from textile wastewater. The maximum removal efficiency of PH obtained was 98.1 % and that of PP was 92.7 %.
Journal of Colloid and Interface Science, 2009
The present investigation assesses the applicability of waste materials-bottom ash and deoiled soya-for the removal of the colorant Congo red from wastewaters. The adsorption characteristics and dye removal efficiency of adsorbents have been determined by investigating factors such as effect of pH, effect of concentration of the dye, amount of adsorbents, contact time, and temperature. Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherm models have been used to evaluate the ongoing adsorption. With the help of adsorption isotherm data different thermodynamic parameters such as free energy; enthalpy, and entropy have been calculated. The estimated free energy has been obtained as À21.52 kJ mol À1 for bottom ash and À16.88 kJ mol À1 for deoiled soya. On the basis of pseudo-first-order and pseudo-second-order kinetic equations different kinetic parameters have been obtained. Column operations depicted good adsorptive tendencies for Congo red with 96.95% and 97.14% saturation of dye on bottom ash and deoiled soya, respectively. Regeneration of the saturated columns has been made by eluting NaOH solution and more than 90% dye has been recovered in both cases.