270
Views
9
CrossRef citations to date
0
Altmetric
Original Articles

Adsorption of cationic dyes onto biopolymer-bentonite composites: kinetics and isotherm studies

, , & ORCID Icon
Pages 8467-8489 | Received 18 Sep 2020, Accepted 04 Nov 2020, Published online: 23 Nov 2020
 

ABSTRACT

Two biopolymer-bentonite composites, namely, bentonite-alginate beads (BAB) and bentonite-alginate-double walled carbon nanotube beads (BACB) were prepared. The synthesised adsorbent beads were characterised using Brunauer-Emmet-Teller (BET) analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD) and Thermogravimetric Analysis (TGA). Batch adsorption studies were performed to assess the dye removal capacity of both adsorbents. Three cationic dyes, namely, Methylene blue (MB), Crystal violet (CV) and Rhodamine B (RB) were used to evaluate the adsorption capacities of the prepared adsorbents. Thermodynamic studies were carried out at different temperatures to assess the adsorption behaviour of both adsorbents. Various kinetic models, i.e., pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD) models were studied to determine the adsorption kinetics whereas Freundlich and Temkin isotherm models were utilised to study adsorption at equilibrium. Adsorption data of both BAB and BACB fitted well with Freundlich as well as Temkin isotherm for all dyes under investigation. Kinetics data of BAB and BACB followed PSO model and both adsorbents exhibited the highest adsorption capacity for MB (267.14 mg g−1 and 400.55 mg g−1, respectively) amongst the dyes under study. The dye removal efficiency of both the adsorbents followed the order MB > CV > RB. Regeneration studies revealed that the dye removal percentage ranged from 51% to 93% up to six adsorption-desorption cycles.

Acknowledgments

The authors wish to acknowledge Central Instrumentation Facility, Jamia Millia Islamia University, New Delhi for FTIR analysis, Advanced Instrumentation Research Facility, JNU, New Delhi for XRD analysis, University Science Instrumentation Centre, University of Delhi for TGA analysis and Sophisticated Analytical Instrumentation Facility, AIIMS, New Delhi for their contribution on SEM analysis.

Disclosure statement

The authors have no potential conflict of interest.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.