# Utilization of Organic Solvents for the Recycling of Waste Wooden Railroad Ties

## TL;DR

This study explores using organic solvents to clean and recycle old railroad ties contaminated with coal tar creosote oil.

## Contribution

The study introduces solvent extraction as a novel method for decontaminating and recycling waste wooden railroad ties.

## Key findings

- Dichloromethane extracted the highest amount of polycyclic aromatic hydrocarbons from railroad tie chips.
- The extraction efficiency of solvents followed a specific order, with dichloromethane being the most effective.
- Solvent extraction is proposed as a simple, low-energy, and scalable method for treating contaminated wood waste.

## Abstract

Wooden waste railroad ties preserved with coal tar creosote oil represent a specific source of polluting substances. The aim of this study was to investigate and compare extraction capacity due to solvent extraction of fifteen frequently used organic solvents for the purpose of decontamination treatment of waste wooden railroad ties, while recovering wood for reuse. Pure organic solvents, ethanol 96%, propan-2-ol, deionized water, dichloromethane, acetone, n-hexane, mixture n-hexane/acetone (V/V = 1/1), cyclohexane, methanol, N,N-dimethyl formamide, toluene, ethyl acetate, acetonitrile, amyl acetate, medical gasoline, n-pentane and n-butyl acetate were for leaching pollutants from waste railroad ties. The highest extraction capacity was achieved using dichloromethane, where 7.50 to 7.89 wt.% of total sixteen polycyclic aromatic hydrocarbons were extracted from waste railroad tie chips. The most promising solvents for the treatment exhibited extraction efficiency which decreases in a series dichloromethane > n-hexane/acetone > acetone > methanol > ethanol 96% > propan-2-ol > cyclohexane > toluene > n-hexane. Solvent extraction represents a novel approach for treatment of wooden waste railroad ties. The experiments are based on the search for a management process for the treatment of wood waste railroad ties that is simple, low energy consumption, efficient and could potentially be applied for large scale.