Deep insights into kinetics, optimization and thermodynamic estimates of methylene blue adsorption from aqueous solution onto coffee husk (Coffee arabica) activated carbon

Prabu Deivasigamani; P Senthil Kumar; Sathish Sundaraman; Michael Rahul Soosai; A Annam Renita; Karthikeyan M; Nessipkhan Bektenov; Omirserik Baigenzhenov; Venkatesan D; Aravind Kumar J

doi:10.1016/j.envres.2023.116735

Deep insights into kinetics, optimization and thermodynamic estimates of methylene blue adsorption from aqueous solution onto coffee husk (Coffee arabica) activated carbon

Environ Res. 2023 Nov 1;236(Pt 2):116735. doi: 10.1016/j.envres.2023.116735. Epub 2023 Jul 28.

Affiliations

¹ Department of Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai, Tamilnadu, 600119, India. Electronic address: dprabhu78@gmail.com.
² Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai, Tamilnadu, 603110, India; Centre of Excellence in Water Research (CEWAR), Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam, 603110, Tamil Nadu, India; School of Engineering, Lebanese American University, Byblos, Lebanon; Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, 140413, India.
³ Department of Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai, Tamilnadu, 600119, India.
⁴ Institute of Natural Sciences and Geography, Abai University, Almaty, 050010, Kazakhstan; JSC «Institute of Chemical Sciences named after A.B. Bekturov», Almaty, 050010, Kazakhstan.
⁵ Department of Metallurgical Engineering, Satbayev University, Almaty, Kazakhstan.
⁶ Department of Energy and Environmental Engineering, Saveetha School of Engineering, SIMATS, Chennai, Tamilnadu, 602105, India. Electronic address: arvindhjsbu@gmail.com.

PMID: 37517489
DOI: 10.1016/j.envres.2023.116735

Abstract

In the current study, an attempt was made to synthesize coffee husk (CH) activated carbon by chemical modification approach (sulphuric acid-activated CH (SACH) activated carbon) and was used as a valuable and economical sorbent for plausible remediation of Methylene blue (MB) dye. Batch mode trials were carried out by carefully varying the batch experimental variables: SACH activated carbon (SACH AC) dosage, pH, initial dye concentration, temperature, and contact time. The optimum equilibrium time for adsorption by SACH activated carbon was obtained as 60 min, and the maximum adsorption took place at 30 °C. Morphological and elemental composition, crystallinity behaviour, functional groups, and thermal stability were examined using SEM with EDX, XRD, FTIR, BET, TGA, and DTA and these tests showed successful production of activated carbon. The outcomes showed that chemical activation enhanced the number of pores and roughness which possibly maximized the adsorptive potential of coffee husk. The Box-Benken design (BBD) was used to optimize the MB dye adsorption studies and 99.48% MB dye removed at SACH AC dosage of 4.83 g/L at 30 °C for 60 min and pH 8.12, and the maximum adsorption was yielded for sulphuric acid-activated coffee husk carbon carbon with 88.1 mg/g maximum MB adsorption capacity. Langmuir- Freundlich model deliberately provided a better fit to the equilibrium data. The SACH AC-MB dye system kinetics showed a high goodness-of-fit with pseudo second order model, compared to other studied models. Change in Gibbs's free energy (ΔG^o) of the system indicated spontaneity whereas low entropy value (ΔS^o) suggested that the removal of MB dye on the SACH activated carbon was an enthalpy-driven process. The exothermic nature of the sorption cycle was affirmed by the negative enthalpy value (ΔH^o). The adsorptive-desorptive studies reveal that SACH AC could be restored with the maximum adsorption efficiency being conserved after the fifth cycles. Overall, the outcomes revealed that sulphuric acid-activated coffee husk activated carbon (SACH AC) can be used as prompt alternative for low-cost sorbent for treating dye-laden synthetic wastewaters.

Keywords: Adsorption; Equilibrium; Kinetics; MB dye; Thermodynamics; Waste coffee husk.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Charcoal
Coffea*
Hydrogen-Ion Concentration
Kinetics
Methylene Blue / analysis
Thermodynamics
Water / chemistry
Water Pollutants, Chemical* / analysis

Substances

sulfuric acid
Methylene Blue
Charcoal
Water Pollutants, Chemical
Water