# Biosorption of Cu2+ and Zn2+ by Rhodotorula sp. Kt, a Yeast Isolated from Acid Mine Drainage

## TL;DR

A yeast isolated from mine drainage effectively removes copper from contaminated water, showing potential for eco-friendly bioremediation.

## Contribution

Rhodotorula sp. Kt demonstrates high Cu2+ biosorption efficiency and chemisorption mechanism, offering a novel microbial solution for AMD remediation.

## Key findings

- Rhodotorula sp. Kt achieves 71.5% Cu2+ removal at pH 6 and 3 g/L biomass.
- Biosorption kinetics follow pseudo-second-order model, indicating chemisorption.
- SEM-EDS confirms Cu2+ binding to yeast surface, supporting ICP-OES data.

## Abstract

What are the main findings?
Rhodotorula sp. Kt achieves 71.5% Cu2+ removal (pH 6 and 3 g/L), outperforming Zn2+ biosorption.Metal uptake fits pseudo-second-order kinetics (R2 > 0.99), indicating chemisorption.The Langmuir isotherm (R2 = 0.93) indicated monolayer adsorption with high affinity toward Cu2+.SEM-EDS confirmed surface Cu binding, supporting ICP-OES data despite a low surface signal.

Rhodotorula sp. Kt achieves 71.5% Cu2+ removal (pH 6 and 3 g/L), outperforming Zn2+ biosorption.

Metal uptake fits pseudo-second-order kinetics (R2 > 0.99), indicating chemisorption.

The Langmuir isotherm (R2 = 0.93) indicated monolayer adsorption with high affinity toward Cu2+.

SEM-EDS confirmed surface Cu binding, supporting ICP-OES data despite a low surface signal.

What are the implications of the main findings?
The yeast isolate shows promise as a cost-effective, eco-friendly biosorbent for acid mine drainage and Cu-rich waters.pH dependence and kinetics indicate that cell-wall functional groups drive metal uptake, guiding future optimization.The combined analyses provide a solid basis for improving microbial metal-removal systems.

The yeast isolate shows promise as a cost-effective, eco-friendly biosorbent for acid mine drainage and Cu-rich waters.

pH dependence and kinetics indicate that cell-wall functional groups drive metal uptake, guiding future optimization.

The combined analyses provide a solid basis for improving microbial metal-removal systems.

Acid mine drainages (AMDs) enriched with toxic metals pose a significant environmental risk. Microbial bioremediation offers a sustainable and cost-effective approach for metal removal from AMD. In this study, a wild yeast isolated from the Kavart abandoned mine, identified as Rhodotorula sp., was evaluated for its copper (Cu2+) and zinc (Zn2+) biosorption ability. Biosorption was strongly pH-dependent. Cu2+ and Zn2+ removal was most efficient (48.1% or 10.07 mg/g and 35.7% or 6.07 mg/g, respectively) at pH 6. Increasing the biomass to 3 g/L at the same pH enhanced Cu2+ removal to 71.5% (26 mg/g). Biosorption kinetic analysis showed an excellent fit to the pseudo-second-order model (R2 > 0.99), indicating that the mechanism is chemisorption-dominated. Equilibrium data followed the Langmuir isotherm (R2 = 0.93), consistent with monolayer adsorption on homogeneous binding sites. SEM-EDS analysis confirmed Cu2+ association with the yeast surface, supporting the ICP-OES results. The results demonstrate the isolate as a promising biosorbent, particularly for Cu2+, and highlight its potential application in the remediation of AMD-contaminated waters.