Efficient COD removal of diesel-contaminated wastewater using coconut shell-based magnetic activated carbon

Abstract

Oil contaminants present substantial hazards to the environment and human health by virtue of their carcinogenic, mutagenic, and toxic characteristics. Water supplies are regularly contaminated by common components of crude oil and petrol, such as benzene. Conventional approaches to wastewater purification fail to adequately eliminate these pollutants derived from oil. Adsorption, a critical method frequently used for separation and purification in which molecules adsorb to surfaces, is a purification technique. Coconut shell magnetic activated carbon (CSMAC) was prepared from coconut shell wastes through pyrolysis and co-precipitation and employed as an adsorbent in diesel-contaminated water. The chemical co-precipitation technique was used to synthesize magnetic activated carbon, which involves the reduction of FeSO₄ and FeCl₃ with metallic ions using a NaOH solution The effectiveness of the CSMAC was compared against that of commercial activated carbon-based adsorbents—both magnetic and non-magnetic—for chemical oxygen demand (COD) removal from oily wastewater. The effect of variables such as PH, Temperature, pollutant concentration, and adsorbent dosage were investigated and optimized on the COD removal by the adsorbent. Fourier-transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction, ZETA potential, and BET were used as characterization techniques to determine the properties of the synthesized adsorbent. The characterization analyses revealed that the prepared magnetic nanocomposites had sufficient magnetic saturation for quick and easy recovery, interconnected pores, and different functional groups. Subsequently CSMAC nanocomposite was used as adsorbent for removing diesel from contaminated water. The result revealed 93% of COD reduction under optimal conditions—temperature of 35 °C, adsorbent dosage of 0.5 g, pH of 7.0, and contact duration of 2 h. The sorption mechanism fit best in the Langmuir isotherm, and followed the first order kinetics with a satisfactory correlation coefficient of R² = 0.97. The results of the comparison between commercial magnetic activated carbon CMAC and Coconut shell magnetic activated carbon CSMAC, showed CSMAC gave an 80% removal efficiency which was significantly higher than that of commercial magnetic activated carbon.

Keywords:

• Characterization
• diesel
• magnetic nanoparticles
• nanocomposite
• sorption

Acknowledgment

The study did not receive any funder.

Author contributions

Cynthia Ezeaniekwe: Conceptualization, Experimentation; Evidence Akhayere: Supervision Experimentation, Manuscript Writing, Doga Kavaz: Supervision, Manuscript Writing, Conceptualization, and Experimentation.

Disclosure statement

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

Data availability statement

Data is readily available at request from the corresponding author.