Removal of Methylene Blue from a synthetic effluent by ionic flocculation

Yago Neco Teixeira; Francisco José de Paula Filho; Vinícius Pereira Bacurau; Jorge Marcell Coelho Menezes; Anderson Zhong Fan; Ricardo Paulo Fonseca Melo

doi:10.1016/j.heliyon.2022.e10868

Removal of Methylene Blue from a synthetic effluent by ionic flocculation

Heliyon. 2022 Oct 3;8(10):e10868. doi: 10.1016/j.heliyon.2022.e10868. eCollection 2022 Oct.

Authors

Yago Neco Teixeira^{1

2}, Francisco José de Paula Filho^{1

2}, Vinícius Pereira Bacurau³, Jorge Marcell Coelho Menezes², Anderson Zhong Fan³, Ricardo Paulo Fonseca Melo⁴

Affiliations

¹ Agrarian Sciences and Biodiversity Center, Federal University of Cariri, Ícaro Moreira de Sousa St, 126, 63130-025, Crato, Ceará, Brazil.
² Science and Technology Center, Federal University of Cariri, Av. Ten. Raimundo Rocha, 1639, 63048-080, Juazeiro do Norte, Ceará, Brazil.
³ Materials Engineering Department, Federal University of São Carlos, Rod. Washington Luiz, 235, 13565-905, São Carlos, São Paulo, Brazil.
⁴ Exact and Natural Sciences Department, Federal University of Semi-Árido, BR 226, n-n, 59900-000, Pau dos Ferros, Rio Grande do Norte, Brazil.

Abstract

Methylene Blue (MB) is a dye widely used in the industrial sector and in human and veterinary pharmacology. This dye, if improperly disposed of, can cause a significant environmental impact due to its low biodegradability, as it is a stable and complex substance. Additionally, it may affect human health and generate highly toxic byproducts. Hence, the purpose of this work is to assess the removal efficiency of MB from a synthetic effluent using a ionic flocculation process. Such a process consists of the dissolution of a biodegradable anionic surfactant (obtained from soybean oil used for frying food) in the synthetic effluent and the subsequent addition of calcium to the system. The addition of Ca leads to the formation of insoluble surfactant flocs with a high capacity to adsorb organic pollutants. The FTIR testing showed the presence of OH^- and C=O groups in the surfactant flocs, which favor the removal of MB by an adsorption process. The maximum adsorption capacity of MB was 101.38 mg g^-1. The process is in fact a chemisorption and has an exothermic nature. Desorption studies showed a desorption efficiency of up to 47.81% using an ethanol 1:2 solution. An MB removal efficiency of up to 93.71% was attained in just 0.5 min for an initial MB concentration of 100 mg L^-1, showing that ionic flocculation is a very fast and effective process for the treatment of effluents.

Keywords: Adsorption; Desorption; Ionic flocculation; Methylene Blue; Surfactant.