Actas Pink-2B dye removal in biochar nanocomposites augmented vertical flow constructed wetland (VF-CWs)

Abstract

Industries generate hazardous dye wastewater, posing significant threats to public health and the environment. Removing dyes before discharge is crucial. The ongoing study primarily focused on synthesizing, applying, and understanding the mechanism of green nano-biochar composites. These composites, including zinc oxide/biochar, copper oxide/biochar, magnesium oxide/biochar, and manganese oxide/biochar, are designed to effectively remove Actas Pink-2B (Direct Red-31) in conjunction with constructed wetlands. Constructed wetland maintained pH 6.0–7.9. At the 10th week, the copper oxide/biochar treatment demonstrated the highest removal efficiency of total suspended solids (72%), dissolved oxygen (7.2 mg/L), and total dissolved solids (79.90%), followed by other biochar composites. The maximum removal efficiency for chemical oxygen demand (COD) and color was observed at a retention time of 60 days. The electrical conductivity also followed the same order, with a decrease observed up to the 8th week before becoming constant. A comprehensive statistical analysis was conducted, encompassing various techniques including variance analysis, regression analysis, correlation analysis, and principal component analysis. The rate of color and COD removal followed a second-order and first-order kinetics, respectively. A significant negative relationship was observed between dissolved oxygen and COD. The study indicates that employing biochar composites in constructed wetlands improves textile dye removal efficiency.

Graphical Abstract

NOVELTY STATEMENT

The novelty of this study is the selection of Cymbopogon as a proper plant for phytoremediation of dye along with green metal oxide coated biochar. These were selected due to their good ability to remove organic pollutant. This study demonstrates the uptake and degradation processes of persistent dye in constructed wetland.

Keywords:

• Direct Red-31 dye
• water quality
• kinetic studies

Acknowledgment

The authors would like to extend their sincere appreciation to the acknowledgment; research supporting project (RSP- 2024/95, King Saud University, Riyadh, Saudi Arabia).

Consent for publication

All authors have read and approved this manuscript.

Disclosure statement

The authors declare no competing interests.

Author contributions

Ruba Munir: Methodology, Conceptualization, Writing – original draft, Resources, Formal Analysis; Saima Noreen: Supervision, Resources, Writing-review & editing; Murtaza Sayed: Validation, Writing-review & editing; Amna Muneer: Formal analysis, Statistical analysis, Writing-review & editing; Fazila Younas: Conceptualization, Writing-review & editing; Muhammad Fahad Sardar: Writing-review & editing; Gadah Albasher: Writing-review & editing.

Ethical approval

Not applicable.

Consent to participate

Not applicable.

Data availability

Data will be made available on reasonable request.