Efficient Removal of Methyl Orange and Alizarin Red S from pH-Unregulated Aqueous Solution by the Catechol–Amine Resin Composite Using Hydrocellulose as Precursor

Electrocoagulation (EC) was used for the removal of anthraquinone dye, Alizarin Red S (ARS) from aqueous solution, the process was carried out in a batch electrochemical cell with Al electrodes in monopolar connection. The effects of some important parameters such as current density, pH, temperature and initial dye concentration, on the process were investigated. Equilibrium was attained after 10 minutes at 30 oC. Pseudo-ﬁrst-order, pseudo-second-order, Elovic, and Avrami kinetic models were used to test the experimental data in order to elucidate the kinetic of the electrocoagulation process; pseudo-first-order and Avrami models best ﬁtted the data. Experimental data were analyzed using six isotherm models: Langmuir, Freudlinch, Redlich–Peterson, Temkin, Dubinin–Radushkevich and Sips isotherms and it was found that the data fitted well with Dubinin–Radushkevich and Sips isotherm model. The study showed that the process depend on current density, temperature, pH and initial dye concentration. The calculated thermodynamics parameters (∆Go, ∆Ho and ∆So) indicated that the process is spontaneous and endothermic in nature.

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Anionic Dye Removal by Polypyrrole-Modified Red Mud and Its Application to a Lab-Scale Column: Adsorption Performance and Phytotoxicity Assessment

Adsorption Science & Technology ◽

10.1155/2021/7694783 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Feng Zhang ◽

Yue Yin ◽

Chunlei Qiao ◽

Ya-nan Luan ◽

Mengyan Guo ◽

...

Keyword(s):

Aqueous Solution ◽

Methyl Orange ◽

Red Mud ◽

Congo Red ◽

Dye Removal ◽

Column Studies ◽

Efficient Removal ◽

Adsorption Capacities ◽

Column Adsorption ◽

Bean Sprouts

In this study, polypyrrole-modified red mud (PRM) was prepared for the efficient removal of anionic dyes (methyl orange and Congo red) from aqueous solutions. The phytotoxicity (bean sprouts) of the dye solution before and after dye removal was investigated. Adsorption kinetics confirmed that the adsorption of methyl orange (MO) and Congo red (CR) on PRM was controlled by chemical reactions between the functional groups of polypyrrole and dyes. From Langmuir isotherm fitting, we found the theoretical adsorption capacities of MO and CR on PRM were 194.1 and 314.9 mg/g, respectively. The adsorption progress of MO and CR on PRM was found to be spontaneous and endothermic. The column studies demonstrated that, under dynamic flow, the PRM can efficiently remove MO and CR from aqueous solution, with adsorption capacities of 31.08 and 55.04 mg/g, respectively. In the toxicity test, the phytotoxicity of the column effluents (after dye removal) was significantly lowered compared to the initial dye influents. After the removal of MO and CR, the average root length of bean sprouts was increased from 3.30 cm to 5.18 cm and from 3.01 cm to 7.00 cm, respectively. These findings highlighted the efficient removal of dyes by PRM from aqueous solution, demonstrating the possible application of PRM for the removal of dye from dye-contaminated wastewaters.

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