# Industrial Winemaking Waste to Sustainable Palladium(II) Recovery: A Green One-Step Synthesis of Activated Carbon from Grape Seeds

## TL;DR

This paper shows how grape seeds from winemaking can be turned into a material that efficiently recovers palladium, a valuable metal, in an eco-friendly way.

## Contribution

A novel one-step synthesis of activated carbon from grape seeds for Pd(II) recovery, eliminating energy-intensive activation steps.

## Key findings

- AC from grape seeds at 400 °C showed high Pd(II) adsorption (16.20 mg/g) without complex activation.
- The method reduced environmental impact by 74% and acidification potential by 92% compared to coal-based AC.
- Higher pyrolysis temperatures increased surface basicity and carboxylic group content.

## Abstract

The growing demand for palladium (Pd) necessitates the development of sustainable and efficient recovery methods. This work presents a green, one-step synthesis of activated carbon (AC) from winemaking waste (grape seeds) via direct pyrolysis, eliminating the need for separate, energy-intensive activation. Remarkably, the AC synthesized at the lowest temperature of 400 °C exhibited the highest Pd(II) adsorption capacity (16.20 mg/g at 50 °C), performing comparably to many literature-reported ACs that underwent complex activation processes. Characterization revealed that this optimal material possessed a favorable point of zero charge (PZC 7.78) and the lowest ash content (4.66%). Higher pyrolysis temperatures (400–800 °C) progressively increased surface basicity (PZC up to 11.00) and carboxylic group content (reaching 0.565 mmol/g at 800 °C). A comprehensive life cycle assessment (LCA) demonstrated the significant environmental advantage of this method, showing a 74% lower total environmental impact and a 92% reduction in acidification potential compared to commercial coal-based AC. These results prove that highly effective Pd(II) recovery can be achieved through a simplified, direct pyrolysis process, offering a sustainable and practical approach for precious metal recycling from waste biomass.