Continuous fixed-bed column study and adsorption modeling removal of Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ ions from synthetic acid mine drainage by nanocomposite cellulose hydrogel

Abstract

Heavy metal ions are widely recognized for their harmful effects on human health and the environment. Heavy metal ions removal using nanocomposite hydrogel is a promising method for industrial applications and process development owing to their utilization in both kinematic and dynamic adsorption process. There is a need to develop simple, low-cost water purification techniques that use biodegradable bio-based natural polymers like cellulose nanocrystal that have been modified with nanomaterials. These innovative functional cellulose nanocrystals-based nanomaterials have been shown to successfully remove a variety of contaminants from wastewater to acceptable levels. Due to their capacity to hold water in their porous structures, hydrogels are the most commonly used 3D polymer mesh materials for environmental remediation. The application of potential hydrogel for the absorption of Cu²⁺, Ni²⁺, Zn²⁺ and Cd²⁺ ions from an aqueous solution in a packed bed adsorption column was studied in this work. The adsorbent was studied using FTIR, SEM, XRD and TGA. The influence of breakthrough factors such as bed height (10, 17 and 25 cm) influent concentration (10, 20 and 50 mg/L) and the feed flow rate (10, 20 and 30 mL/min) was assessed. Bed Depth Service Time, Thomas and Yoon–Nelson models were used to fit the experimental data. With an increase in bed height, breakthrough and exhaustion time, the removal efficiency rose to 99.42 ± 0.12 for Cu²⁺, 99.23 ± 1.16 for Ni²⁺, 99.36 ± 0.89 for Cd²⁺ and 98.94 ± 0.48 for Zn²⁺, but declined with increased flow rate and influent concentration. Better performance was observed at a bed height of 25 cm, an influent metal ion concentration of 10 mg/L and a flow velocity of 10 mL/min. The BDST and Yoon–Nelson models were both successfully used to predict the breakthrough curves of heavy metal ions removal.

Keywords:

• Hydrogel
• metal ions adsorption
• modeling
• fixed-bed column
• kinetic parameters
• acid mine drainage

Data statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

Declaration of competing interest

The authors declare that they have no known competing for financial interests or personal relationships that could have influenced the work reported in this paper.

Additional information

Funding

This work was financially supported by the Paper manufacturers association of South Africa (PAMSA) and the Department of Science and Innovation (South Africa).