Factorial experimental design optimisation of adsorption process for removing chrome ion using crude biomass

ABSTRACT

The pollution of water and the environment by heavy metals has recently increased dramatically, creating a severe environmental problem due to their non-biodegradability and high toxicity. Among these metals, we are interested in chromium (Cr), essential for human life but can be toxic in large quantities. It is vital to develop a simple, effective, and inexpensive method for its removal from aqueous media. This work aims to combine two aspects: environmental protection and waste recovery. We studied the adsorption capacity of Cr(VI) by biomass consisting of a mixture of walnut shells, pecan nuts, and peanuts. The ion was quantified using high-resolution magnetic sector inductively coupled plasma mass spectrometry, and several techniques characterised the raw adsorbent. To optimise the removal of Cr(VI), four factors were optimised using a 2⁴-full factorial design, enabling us to determine the optimum adsorption conditions: a contact time of 360 min, an adsorbent mass of 30 mg, an initial ion concentration of 50 mg/L, and a pH of 6. The response efficiency Y (Qe) achieved its optimum at 58.47976 ± 4.168804 (mg/g), resulting in a maximum desirability of 0.957419. The adsorption phenomenon was studied kinetically, and it was found to follow the pseudo-first-order reaction (R² = 0.9894); concerning adsorption isotherms, the Freundlich isotherm proved to be the best (R² = 1). Overall, the present biosorbent demonstrates excellent capacity to remove Cr (VI) from water and can be used on a large scale.

KEYWORDS:

• Heavy metal
• high-resolution magnetic sector inductively coupled plasma mass spectrometry (HR-ICP-MS)
• bio-adsorbent
• full factorial design
• wastewater treatment
• Freundlich isotherm

Disclosure statement

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