Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption

Nouioua, Asma; Ben Salem, Dhirar; Ouakouak, Abdelkader; Guergazi, Saadia; Abdelli, Abdelouaheb; Goma, Daniel; Gatica, Jose Manuel; Vidal, Hilario

doi:10.3390/toxics13121039

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Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption

by

Asma Nouioua

^1,2,*,

Dhirar Ben Salem

¹

,

Abdelkader Ouakouak

³

,

Saadia Guergazi

^1,4,

Abdelouaheb Abdelli

⁵,

Daniel Goma

^6,7

,

Jose Manuel Gatica

^6,*

and

Hilario Vidal

⁶

¹

Research Laboratory in Subterranean and Surface Hydraulics, University of Biskra, PO Box 145, Biskra 07000, Algeria

²

Department of Industrial Chemistry, Faculty of Science and Technology, University of Biskra, P.O. Box 145, Biskra 07000, Algeria

³

Hydraulic and Civil Engineering Department, University of El Oued, P.O. Box 789, El Oued 39000, Algeria

⁴

Civil Engineering and Hydraulic Department, University of Biskra, P.O. Box 145, Biskra 07000, Algeria

⁵

Department of Quality Control, ENASEL Unit, El-Outaya Complex, Biskra 07030, Algeria

⁶

Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica e Instituto de Microscopía Electrónica y Materiales (IMEYMAT), Universidad de Cádiz, 11510 Puerto Real, Spain

⁷

School of Chemistry and Chemical Engineering, Queen’s University Belfast, David-Keir Building, Strandmillis Road, Belfast BT9 5AG, UK

^*

Authors to whom correspondence should be addressed.

Toxics 2025, 13(12), 1039; https://doi.org/10.3390/toxics13121039

Submission received: 31 October 2025 / Revised: 27 November 2025 / Accepted: 28 November 2025 / Published: 30 November 2025

(This article belongs to the Special Issue Carbon-Based Materials for Pollutant Immobilization and Removal in Soil and Water)

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Abstract

This study introduces an innovative hybrid approach combining salting-out and adsorption for the highly efficient removal of crystal violet (CV) dye from aqueous solutions. The method leverages high-ionic-strength brine discharge from the Complex of El-Outaya (CEO, ENASEL, Biskra, Algeria) and micro-mesoporous biochar derived from calves’ horn cores (BHC-800). Results demonstrate that both undiluted and diluted brine significantly enhance CV removal, while BHC-800, with a surface area of 258 m² g⁻¹, exhibits a maximum Langmuir adsorption capacity of 106.1 mg g⁻¹ (at 20 °C ± 2). Thermodynamic analysis confirms a spontaneous (ΔG° < 0) and exothermic (ΔH° = −0.86 kJ mol⁻¹) process, with increased interfacial disorder (ΔS° = 93.53 J mol⁻¹ K⁻¹). The synergistic effect of salting-out and adsorption achieved ~99.8% removal of CV at an initial concentration of 1000 mg L⁻¹. Furthermore, BHC-800 exhibited excellent reusability, maintaining high adsorption efficiency over multiple cycles. Economic assessment revealed operational costs of 0.45–0.89 US$ m⁻³ for 60% brine discharge. Biochar production costs were 0.076–0.18 US$ kg⁻¹, translating to 7.5–17.2 (10⁻⁴ US$) per gram of CV removed. This dual strategy not only offers an eco-friendly and cost-effective solution for dye-laden water but also promotes the valorization of saline effluents and animal byproducts, addressing critical environmental challenges in industrial wastewater treatment.

Keywords: brine discharge; biochar; crystal violet removal; mechanisms; cost analysis

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MDPI and ACS Style

Nouioua, A.; Ben Salem, D.; Ouakouak, A.; Guergazi, S.; Abdelli, A.; Goma, D.; Gatica, J.M.; Vidal, H. Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption. Toxics 2025, 13, 1039. https://doi.org/10.3390/toxics13121039

AMA Style

Nouioua A, Ben Salem D, Ouakouak A, Guergazi S, Abdelli A, Goma D, Gatica JM, Vidal H. Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption. Toxics. 2025; 13(12):1039. https://doi.org/10.3390/toxics13121039

Chicago/Turabian Style

Nouioua, Asma, Dhirar Ben Salem, Abdelkader Ouakouak, Saadia Guergazi, Abdelouaheb Abdelli, Daniel Goma, Jose Manuel Gatica, and Hilario Vidal. 2025. "Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption" Toxics 13, no. 12: 1039. https://doi.org/10.3390/toxics13121039

APA Style

Nouioua, A., Ben Salem, D., Ouakouak, A., Guergazi, S., Abdelli, A., Goma, D., Gatica, J. M., & Vidal, H. (2025). Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption. Toxics, 13(12), 1039. https://doi.org/10.3390/toxics13121039

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Ultra-Efficient Removal of Crystal Violet Dye Using Industrial Brine and Horn-Derived Biochar: Synergistic Action of Salting-Out/Adsorption

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