Valorization of cardboard waste adsorbents for efficient malachite green removal – equilibrium, kinetics, and thermodynamics

ABSTRACT

This work was aimed at evaluating the adsorptive properties of cardboard waste-based adsorbents for malachite green removal. The adsorbents were produced through hydrothermal carbonization and/or phosphoric acid activation and characterized for specific area, surface morphology, and functional groups. Batch adsorption was performed at varying concentrations, contact times, and temperatures. Results show that the activated carbon derived from cardboard waste with surface area of 196 m²/g exhibits a 134 mg/g (31.6%) adsorption capacity of malachite green. On the other hand, the cardboard hydrochar displays a peak capacity at 400 mg/g (94%) due to dye precipitation before the magnitude subsides to 47 mg/g (5.7%) at higher concentration of 820 mg/L. The equilibrium data of activated carbons could be well described by the Langmuir model, while the kinetics fitted well with the pseudo-second order model. The adsorption of malachite green is endothermic and spontaneous at high solution temperature.

KEYWORDS:

• Activated carbon
• adsorbent
• adsorption
• cardboard waste
• malachite green
• phosphoric acid activation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Availability of data and material

Data will be made available upon request.

Additional information

Funding

This work is supported by Ministry of Higher Education Malaysia through Fundamental Research Grant Scheme, FRGS/1/2022/STG05/UTM/02/5.

Notes on contributors

Rabah Salih Alwan Alarboday

Rabah Salih Alwan Alarboday (Research Student): Conceptualization, methodology, experimental work, analysis, first draft.

Fadina Amran

Fadina Amran (Research Associate): Conceptualization, review, validation, first draft.

Muhammad Abbas Ahmad Zaini

Muhammad Abbas Ahmad Zaini (Associate Professor): Grant recipient, supervision, conceptualization, review, validation.