Adsorption of congo red dye from aqueous solution onto amino-functionalized silica gel

ABSTRACT This study investigates the potential use of amino-functionalized silica gel as an adsorbent for the recovering of congo red dye from aqueous solution. The effects of pH, contact time, and temperature were determined and evaluated. Equilibrium isotherms were also studied. The adsorption kinetics was modeled by pseudo-first order and pseudo-second order. Furthermore, desorption of congo red was preliminarily studied. The pH range from 4.5 to 7.0 was favorable for the adsorption of congo red onto amine modified silica at 25ºC. Higher adsorption capacity was obtained at 50ºC. Langmuir and Freundlich models were fitted to the adsorption equilibrium data. The best fittings were obtained with the pseudo-second order and Langmuir model for kinetics and equilibrium, respectively. Desorption studies suggest that ion exchange might be the major mode of adsorption. KOH solution was the best desorbing agent for recovering the adsorbed dye.

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Brewer’s grains with different pretreatments used as bio-adsorbents for the removal of Congo red dye from aqueous solution

BioResources ◽

10.15376/biores.15.3.6928-6940 ◽

2020 ◽

Vol 15 (3) ◽

pp. 6928-6940

Author(s):

Jianguo Wu ◽

Zhao Zhang ◽

Jintao Xu ◽

Xuanxian Lu ◽

Chi Wang ◽

...

Keyword(s):

Experimental Data ◽

Aqueous Solution ◽

Congo Red ◽

Second Order ◽

White Rot ◽

White Rot Fungus ◽

Isotherm Models ◽

Hydroxyl Groups ◽

Congo Red Dye ◽

Red Dye

Brewer’s grains (BG), a by-product of the beer industry, were first pretreated by sulfuric acid, sodium hydroxide, and white-rot fungus Coriolus versicolor for the preparation of bio-adsorbents BGPH, BGPOH, and BGPB, respectively. All bio-adsorbents were rich in hydroxyl groups and could adsorb Congo red dye from aqueous solution, and BGPOH worked better than the others. The order of maximum equilibrium adsorption capacity of bio-adsorbents for Congo red was BGPOH > BGPH > BGPB. The Langmuir, Freundlich, and Temkin adsorption isotherm models all fit well with the experimental data. The negative Gibbs free energy change meant that the adsorption was spontaneous, and lower temperature was useful for the adsorption of Congo red onto the bio-adsorbents. The pseudo first-order and second-order kinetics models fit well with the experimental data, and the second-order kinetics model fit better, which indicated the adsorption was controlled by diffusion phenomena. Brewer’s grains with the three pretreatments could be used as efficient adsorbents for the treatment of dye wastewater.

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ADSORPTION KINETICS, ISOTHERMS, THERMODYNAMICS STUDIES ON THE REMOVAL OF CONGO RED DYE USING ANNONA SQUAMOSA (CUSTARD APPLE) PEEL

Journal of Urban and Environmental Engineering ◽

10.4090/juee.2019.v13n2.228234 ◽

2019 ◽

pp. 228-234

Author(s):

Sarang Agarwal ◽

Sowmya Vilvanathan ◽

Shanthakumar S

Keyword(s):

Aqueous Solution ◽

Congo Red ◽

Adsorption Process ◽

Annona Squamosa ◽

Congo Red Dye ◽

Apple Peel ◽

Custard Apple ◽

Pseudo Second Order ◽

Red Dye ◽

Adsorbent Dose

The present study evaluates the feasibility of an adsorbent prepared from Annona squamosa (custard apple) peel, in removing Congo red dye from its aqueous solution. Batch experiments were carried out to study the effect of various parameters like pH (2-8), adsorbent dose (0.005-0.5 g/100mL), contact time (5-120 min), initial dye concentration (25-200 mg/L) and temperature (298-308 K) to determine its effectiveness as an adsorbent. Maximum dye removal attained at pH 2, adsorbent dose 0.1 g/100mL in equilibrium time of 45 min at 308K. Adsorption kinetics using pseudo-first order and pseudo-second order models, and adsorption isotherm using Langmuir and Freundlich models were studied. The adsorption process was found to follow pseudo-second order kinetic model and more favourably described the Langmuir isotherm model. The Gibbs free energy was found to be negative, signifying the spontaneous nature of the adsorption process. Removal of Congo red dye from its aqueous solution by custard apple peel was found to be an endothermic process. The results of the present study suggest that custard apple can be effectively used as an adsorbent to remove Congo red dye from aqueous solution.

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