Custom and definitive screening designs for evaluating multiple adsorbents: bisphenol-A adsorption onto villi-structured polyaniline/carboxymethyl cellulose composites

ABSTRACT

Polyaniline composites consisting of carboxymethyl cellulose (CMC) have enhanced adsorption properties, but recent studies indicate that the oxidised species – dialdehyde carboxymethyl cellulose (DCMC) – outperforms CMC-based composites. However, these studies fail to study the effect of DCMC's aldehyde content and compare the composites with CMC-based composites; numerous experiments required to investigate each adsorbent for each factor limit such studies. We explored a way to study whether villi-structured polyaniline (VSPANI), its CMC composite (CMC/PANI), and its DCMC composites with 35% (DCMC(A)/PANI) and 77% (DCMC(B)/PANI) aldehyde content would be great adsorbents for removing bisphenol-A (BPA). We first customised a D-optimal screening design to alleviate the pitfalls of definitive screening design (DSD), hence estimating all the main effects: initial concentration, pH, flow rate, adsorbent amount, sample volume and type of adsorbent. We excluded CMC/PANI and DCMC(A)/PANI composites, both with low adsorption capacities of 56.57 and 57.27 mg/g from further investigation. The DSD followed to estimate all second-order effects through which we projected a response surface method (RSM) to optimise and model the active factors. Increasing the aldehyde content on the composites favoured adsorption, but there lacked evidence to suggest VSPANI and DCMC(B)/PANI differed significantly in performance. The models were numerically and graphically proven adequate, explaining 80% and 99% of the variation when predicting removal efficiency and adsorption capacity. VSPANI showed potential as an adsorbent for BPA removal with 85% removal efficiency and 129 mg/g adsorption capacity. This comprehensive approach, combining both designs, allows for sustainable investigation of multiple adsorbents and factors, minimising experimental waste.

GRAPHICAL ABSTRACT

KEYWORDS:

• Adsorption
• carboxymethyl cellulose
• design of experiment
• dialdehyde
• polyaniline

Acknowledgements

The authors gratefully acknowledge the generous support of the MEXT scholarship from the Japanese government. We also extend our appreciation to the ResearchRabbit community, as well as the invaluable contributions from the JMP user community. Special thanks are owed to Phil Kay for insightful discussions and the enlightening webinars hosted by RSC. Additionally, we express our gratitude for the instrumental assistance provided by Prof. Fusheng Li, Prof. Ohya Yutaka, and Prof. Takayuki Ban.

Disclosure statement

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

Author contributions

P.K.K.: conceptualisation, methodology, investigation, formal analysis, visualisation, and writing and reviewing – original draft preparation; L.W.L: supervision and resources.

Data availability statement

All data generated or analysed during this study are included in this published article and its supplementary information files