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. 2026 Feb 28.
doi: 10.1186/s13065-026-01728-x. Online ahead of print.

The utilization of activated carbon derived from polyethylene terephthalate bottle waste, as a sustainable source for removal and recovery of methylene blue and picric acid from aqueous solutions

Asmaa Halima  1 , Magdi E Khalifa  1 , Nasser Mohammed Hosny  2 , Wael I Mortada  3
Affiliations

The utilization of activated carbon derived from polyethylene terephthalate bottle waste, as a sustainable source for removal and recovery of methylene blue and picric acid from aqueous solutions

Asmaa Halima et al. BMC Chem. .

Abstract

In this study, waste polyethylene terephthalate (PET) from discarded bottles was recycled via KOH treatment to produce activated carbon (AC) to remove methylene blue (MB) and picric acid (PA) from contaminated water. The AC produced was characterized by using physicochemical methods to assess its surface porosity, morphology and function groups. Batch adsorption experiments were performed the impact of pH, sorbent amount, time, sample volume, and initial concentration of the target dye on the adsorption efficiency. Adsorption followed the Langmuir isotherm model indicating monolayer adsorption behavior, while kinetics fitted with the pseudo-second-order model. The prepared AC exhibited high maximum adsorption capacities reached 334.4 mg g⁻¹ for MB and 271.7 mg g⁻¹ for PA. Quantitative dye desorption (> 97% recovery) was achieved using H₂SO₄ for MB and NaOH for PA. The method was also applied to spectrophotometric quantification of both analytes, yielding linear calibration curves for MB (0.15-5.76 mg L⁻¹, R² = 0.9997) and PA (0.01-1.68 mg L⁻¹, R² = 0.9980). Detection limits were 0.04 mg L⁻¹ (MB) and 0.003 mg L⁻¹ (PA), with quantification limits of 0.15 mg L⁻¹ (MB) and 0.013 mg L⁻¹ (PA). Successful application to diverse water samples confirmed the method's efficacy for dye removal and quantification.

Keywords: Activated carbon; KOH activation; Methylene blue; Picric acid; Solid phase extraction; Waste PET bottles.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Treated sewage wastewater, Nile River water, and tap water samples were collected within Mansoura City, Egypt. Nile River and tap water samples were obtained from public water sources, while treated wastewater samples were collected from a municipal wastewater treatment facility. According to Egyptian environmental regulations, non-invasive collection of water samples for scientific research purposes does not require specific permits or licenses. All sampling procedures were conducted in compliance with institutional guidelines and national environmental legislation. This study did not involve human participants, animals, or protected species. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

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