Adsorption of congo red dye from aqueous solution onto amino-functionalized silica gel (original) (raw)
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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.
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.
2023
Synthetic dyes were considered harmful due to their toxic, carcinogenic, and nonbiodegradable chemicals. Anionic (congo red (CR) and methyl orange (MO)) and cationic (methylene blue (MB) and Janus green B (JGB)) dyes are used in this study due to their ability to restrict oxygen and sunlight dispersion. The discharge of dyes can degrade aquatic systems. This study has investigated the potential of dyes' adsorption behaviour in silica nanocapsules (SiNCs) adsorbents. Silica nanocapsules (SiNCs) were synthesized using oil-in-water (o/w) emulsion by employing different solvents (ethanol (SiNC E), ethyl ether (SiNC EE), and toluene (SiNC T) to understand the effect of solvents on SINCs' structure and effective dye adsorption. Which found that toluene and ethyl ether were effective solvents to produce silica nanocapsules. SiNC T and SiNC EE were both hollow cores, while the SiNC E structure was spherical. SiNC T adsorbent had high selectivity removal of CR > MO and JGB > MB, in which the adsorption capacity was 0.102 mmol/g at pH 2, 0.029 mmol/g at pH 2, 0.0999 mmol/g at pH 10, and 0.0944 mmol/g at pH 12 for 24 h for CR, MO, JGB, and MB, respectively. The kinetic study shows that the adsorption of dyes follows pseudo-second-order. The experimental data followed the Langmuir isotherm model and gave maximum adsorption capacities of 0.0979 and 0.4147 mmol/g for CR and JGB, respectively. SiNC T was recycled and reused for six consecutive cycles. Developed adsorbents are low-cost, highly efficient, and viable materials to be used in wastewater treatment.
Batch adsorption experiment was conducted to determine how time controls the adsorption rate of Congo red (CR) and Methyl red (MR) dyes using Sugarcane Bagasse granules (SBG), as well as predicting the best fitting kinetic model describing the adsorption process. The result revealed a significant dyes uptake with small changes in time, implying increase in adsorption rate with time. CR has maximum adsorption capacity of 0.8533 mg/g and MR with 0.1951 mg/g and the respective percentage removal of 85.33 % in 30 minutes and 19.51 % within 10 minutes as their respective optimum contact time with SBG at 301±2 K and 20 mgdm -3 dyes solutions. The experimental data of all the dyes closely fit with the pseudo-second order kinetic model. FTIR demonstrated certain changes in the SBG peaks after CR and MR adsorption. According to this study, sugarcane bagasse granules (SBG) can potentially be used for the adsorption of dyes especially Congo red, from aqueous solution for the environmental cleanness.
Removal of water-soluble cationic dyes with TriSyl silicas
Turk J Chem, 1998
In this study, the adsorption of certain water-soluble cationic dyes, (basic blue 9, basic blue 12, basic blue 17, brilliant cresyl blue, janus green B, basic green 4, basic violet 1, basic violet 3, and thionin) onto TriSyl silicas by batch adsorption at 25 ... ° C was investigated. In the ...
Equilibrium studies for the Adsorption of Acid Red 14 and Direct Yellow 86 Dyes Aqueous Solution
This article describe the adsorption of acidic and direct dyes, namely Acid Red 14 (AR14) and Direct Yellow 86 (DY86), from aqueous solution onto activated carbon from walnut shell (ACW) as an eco-friendly and low cost adsorbent. Laboratory prepared ACW were characterized by Barrett-Joiner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) pore structural parameters. The effect of various experimental parameters such as initial dye concentrations, pH and ACW doses were investigated in a batch adsorption technique. Optimum conditions for removal of dyes were found to be pH=1 and 1g of adsorbent dosage in equilibrium time of 48 h. It is shown that, lower equilibrium uptake further increase in temperature, because of the exothermic dyes biosorption process. The plot of the removal versus adsorbent dosage shows the effect of the different frequency of ACW dyes. Equilibrium adsorption isotherms were measured and the experimental data were analyzed using Langmuir, Freundlich and Temkin isotherm equations. It was found that data for DY86 Temkin isotherm is preferred (R 2 =0.93), while for AR14, the Freundlich isotherm is more applicable (R 2 =0.65). The ACW might be successfully used for the removal of dyes from liquid industrial wastewater.
Functionalized mesoporous silica materials for dyes adsorption
Algerian Journal of Environmental Science and Technology, 2021
The mesoporous material silica MCM-41 was synthesized under basic media using pure silica, cetyltrimethylammonium bromide and tetramethylammonium hydroxide at 90°C, and then hydrothermally treated by dihexylamine (DHA) at 130°C for 72 h in order to inflate the pores. The post-synthesized material (DHA-41A), the material obtained after selective ethanol extraction of DHA (DHA-41B) and the organic-free material obtained after carbonization of DHA-41A and/or DHA-41B afford (DHA-41C). Small angle X-ray diffraction, nitrogen adsorption-desorption measurements, FT-IR, thermogravimetry and zetametrie were used to characterize all the samples. The samples were evaluated as adsorbent for two dyes Naphtol Green B (NGB) as anionic dye and Rhodamine B (RB) as cationic dye. DHA-41A and DHA-41C were found to be fast adsorbent for the anionic and the cationic dye respectively. Adsorption capacities of NGB onto DHA-41A and RB onto DHA-41C, were found 444.55 and 372.59 mg/g respectively. Adsorption kinetic data were tested using pseudo-first-order and pseudo-second-order models and intraparticle diffusion. Adsorption data were modeled using Langmuir, Freundlich and Sips adsorption isotherms. The result revealed that the adsorption of the anionic dye onto DHA-41A and the cationic dye onto DHA-41C, fitted very well with the Langmuir and Sips isotherm model naht Freundlich isotherm model.
Adsorption kinetics and mechanism of methyl orange dye on modified silica gel factory waste
The silica gel waste (SGW), collected from solid waste of a local factory at Kolkata, India was modified with cationic surfactant and was utilized as an adsorbing media for the removal of methyl orange dye from aquatic environment. The characterization of base adsorbent and modified adsorbent was carried out. In batch mode, the kinetic study, isotherm study and effect temperature and shaking speed were carried out. The removal efficiency of surfactant modified silica gel waste (SMSGW) in case synthetically prepared wastewater was also examined. The sorption was found to follow the pseudo second order reaction kinetics model and also Langmuir isotherm model. The chemisorption was the rate limiting step for the adsorption process.
Journal of Hazardous Materials, 2008
The conventional adsorbents like activated carbon, agricultural wastes, molecular sieves, etc., used for dye adsorption are unstable in the environment for long time, and hence the adsorbed dyes again gets liberated and pollute the environment. To avoid this problem, environmentally stable adsorbent of silica and alumina should be employed for malachite green adsorption. The adsorbents were characterized by Fourier transformed infrared spectroscopy (FT-IR) to confirm the tetrahedral framework of silica and non-tetrahedral framework of alumina. The adsorption equilibrium of dye on alumina and silica were 4 and 5 h, respectively, this less adsorption time on alumina might be due to the less activation energy on alumina (63.46 kJ mol −1 ) than silica (69.93 kJ mol −1 ). Adsorption increased with increase of temperature on silica, in alumina, adsorption increased up to 60 • C, and further increase of temperature decreased the adsorption due to the structural change of non-tetrahedral alumina in water. The optimum pH for dye adsorption on alumina was 5 and silica was 6. The dye adsorptions on both adsorbents followed pseudo-second-order kinetics. The adsorption well matched with Langmuir and Freundlich adsorption isotherms and found that adsorption capacity on alumina was more than silica. The thermodynamic studies proved that the adsorption was endothermic and chemisorptions ( H • > 40 kJ mol −1 ) on alumina and silica. Recovery of dye on alumina and silica were studied from 30 to 90 • C and observed that 52% of dye was recovered from alumina and only 3.5% from silica. The less recovery on silica proved the strong adsorption of dye on silica than alumina.
Chemical Engineering Journal, 2009
Poly(glycidylmethacrylate) was grafted via surface-initiated-atom transfer radical polymerization (SI-ATRP) on a cross-linked acrylate based resin. Epoxy groups of the grafted polymer, were modified into strong cation-exchange groups (i.e., sulfonic groups) in the presence of sodium sulfite. The adsorption of Crystal Violet and Basic Fuchsine on the strong cation-exchange resin was studied under different experimental conditions. The adsorption process for both basic dyes was pH dependent. The maximum adsorption was observed for both dyes between pH 2.0 and 7.0. The maximum adsorption capacity of the cation-exchange resin for CV and BF dyes were found to be 76.8 and 127.0 mg/g, respectively. Adsorption of the dyes on the resin fitted to Langmuir and Temkin isotherm models and followed the pseudosecond-order kinetics. The values of Gibbs free energy of adsorption ( G • ) were found to be −2.92 and −6.31 kJ/mol at 308 K for CV and BF dyes, respectively. These negative values indicated the spontaneity of the adsorption of the dyes on the resin. Desorption of both dyes was achieved from the resin by using 0.1 M HNO 3 and desorption ratio up to 97% was obtained over seven adsorption/desorption cycles.