Abstract
Mercury, as any other heavy metal, may cause environmental damages due to its accumulation and biotransformation. Dental offices, whether private or institutional, use dental amalgam as a restorative material on a daily basis. Dental amalgam is composed of mercury (50%), silver (30%) and other metals. Approximately 30% of the amalgam prepared in dental offices (0.6 g per capsule) are wasted and inadequately discarded without any treatment. Methods for mercury recovery have been proposed previously, using high temperatures through exposure to direct flame (650 degrees C), long processing time, and hazardous reagents as potassium cyanide. The purpose of this study was to develop a method to replace the direct flame by an electrical mantle in the process of mercury recovery. Results showed an average mercury recovery of 90% from 2 kg of amalgam after 30 minutes of processing time, thus optimizing the procedure. The proposed modifications allowed a significant reduction in processing time and a mercury recovery with high purity. The modified process also provided minimization of operator exposure to physical, chemical and ergonomic hazards, representing a technological advance compared to the risks inherent to the original method. It also provided environmental health and economy of energy resources by replacing a finite energy source (fossil and organic) by a more environmentally appropriate electric source, resulting in significant improvement of the procedure for mercury recovery from dental amalgam.
Highlights
Human activities in general often produce residues, some hazardous to the environment and to mankind
The process of distillation was carried out in a hood with exhaustion escape and started by elevating the temperature of the amalgam container, a 500 ml Kjeldajhl flask (Corning, Big Flats, New York, USA) with an electric mantle until approximately 400°C, where the distilled mercury was further collected in a kitasato kept in ice to facilitate mercury condensation
Graph 1A shows the amount of mercury recovered and the remaining solid residue for each process
Summary
Human activities in general often produce residues, some hazardous to the environment and to mankind. The need for residue control has become evident in order to prevent continuous degradation of natural elements such as water, air and soil. The effects of such indiscriminate pollution affecting mankind have led society to a more conscious thinking of the real danger for future generations.[1]. Several institutions, including Universities, have tried to manage and treat their residues in an attempt to reduce the impact on the environment, leading to promotion of a responsible environmental conscience and triggering critical thinking by students, faculty and staff members regarding appropriate residue disposal.[2].
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