Multi‐Walled Carbon Nanotubes Loaded with Nickel‐Manganese Bimetallic as Three‐Dimensional Particle Electrodes for the Removal of 2,2′‐bipyridine From Photovoltaic Copper Electroplating Wastewater: Process Preparation, Influencing Factors and Mechanisms

Why It Matters

The breakthrough offers a scalable, low‑energy electrochemical method to eliminate a hazardous additive from high‑volume photovoltaic manufacturing streams, reducing environmental and health risks while supporting industry sustainability goals.

Key Takeaways

• Ni-Mn@MWCNTs achieve 88% bipyridine removal
• Optimal Ni:Mn ratio 2:1, 4 mA/cm² current
• Effective across pH 1‑9, reusable catalyst
• Degradation driven by ·OH and ·O₂⁻ radicals
• Toxicity of intermediates markedly reduced

Pulse Analysis

Photovoltaic cell production relies on copper electroplating baths that contain 2,2′‑bipyridine as a cathodic additive, a compound known to inhibit microbial activity and pose neurotoxic risks. Conventional treatment methods—such as adsorption, biological degradation, or advanced oxidation—often struggle with high concentrations, variable pH, and the generation of secondary pollutants. The emergence of a three‑dimensional electrocatalytic platform addresses these gaps by integrating the high surface area of multi‑walled carbon nanotubes with the redox versatility of nickel‑manganese bimetallic particles, creating a robust medium for radical generation.

The Ni‑Mn@MWCNT catalyst operates by electro‑inducing hydroxyl (·OH) and superoxide (·O₂⁻) radicals, which attack the aromatic pyridine rings of bipyridine, leading to rapid mineralization. Laboratory trials demonstrated an 88.09% removal efficiency at a modest current density of 4 mA cm⁻², with optimal performance at a Ni:Mn mass ratio of 2:1. Notably, the system maintained high degradation rates across a broad pH spectrum (1‑9) and could be regenerated multiple cycles without significant loss of activity, underscoring its practical resilience for continuous‑flow wastewater streams.

For the photovoltaic industry, this technology translates into a cost‑effective, environmentally compliant solution that aligns with tightening discharge regulations and corporate sustainability mandates. Its low energy demand and minimal chemical inputs reduce operational overhead, while the lowered toxicity of by‑products eases downstream treatment burdens. Future work may focus on scaling electrode configurations, integrating renewable power sources, and extending the approach to other pyridine‑based contaminants, positioning electrochemical oxidation as a cornerstone of green manufacturing practices.