Physicochemical aspects for the binding mechanism of sodium carboxymethyl cellulose onto mesoporous tea waste carbon from its aqueous solutions

Abstract

This study demonstrated that mesoporous tea waste carbon (MTWC) was successfully prepared from tea waste, an important agricultural waste, after only one chemical modification step, and utilized to adsorption for sodium carboxymethyl cellulose (NaCMC) from its aqueous solutions. The physicochemical characterizations and experiments confirmed that MTWC has very efficient potential adsorptive properties. It was observed that the adsorption of NaCMC on MTWC remarkably affected by the change in adsorptive optimized conditions. The adsorption tests resulted in extent of interaction, various parameters, and determination coefficient (R²) suggested that the adsorption was an exothermic and physical adsorption process which follow the trend Langmuir, Freundlich, Timken and Jovanovic isotherm. Experimental data of the present work were fitted and compared by regression analysis which gave high determination coefficient (R²) > 0.99. The thermodynamic studies indicated that the NaCMC adsorption was spontaneous (ΔG^○˂0) and exothermic (ΔH^○ ˂ 0). The dynamic adsorption study suggested that increase of adsorbent dose in column enhanced the adsorbent capacity of the bed. The desorption studies indicated that sodium hydroxide solution and water regenerated the MTWC for three cycles. The HR-XPS- spectral changes of MTWC before and after adsorption of NaCMC also confirmed the interaction between MTWC and NaCMC. These physicochemical binding aspects of NaCMC onto MTWC provideed substantial evidence to prove beyond doubt that adsorption mainly occured via hydrogen bonding followed by some electronic interactions and such alteration could play a noteworthy role in the field of food, pharmaceutical, and industrial applications without damage of the environment.

Graphical Abstract

Keywords:

• Mesoporous tea waste carbon
• sodium carboxymethyl cellulose
• physicochemical aspects
• adsorption
• thermodynamics
• kinetics

Acknowledgements

The authors are thankful to University Sophisticated Instrumental Centre and Sophisticated Instrumental Lab, Department of Chemistry, Babasaheb Bhimrao Ambedkar University (A Central University) Lucknow, Uttar Pradesh (INDIA) for SEM, FTIR, XRD and BET surface characterization facility respectively.

Additional information

Funding

The financial support to Ashok Kumar from University Grants Commission, New Delhi (173/Conf./DAC/BBAU, 30/09/2016) is gratefully acknowledged.