Chemical Detoxifying Neutralization of ortho-Phthalaldehyde: Seeking the 'Greenest'

摘要

CIDEX~(~R) OPA Solution (containing 0.55% ortho-phthalaldehyde, OPA) is the preferred choice over glutaraldehyde (GTA) as a high-level disinfectant for hospital instrument processing due to its low volatility and high stability. Although OPA degrades naturally in the environment, residual OPA in discharge water may be toxic to organisms in the receiving water, and these solutions should ideally be detoxified prior to discharge. Even though OPA can be neutralized by sodium bisulfite, the neutralized solution is toxic to fish. OPA can also be scavenged by passing through solid supports with covalently bonded amines. However, this method seems not very practical. Ammonia precipitates OPA effectively and instantly from its water solution but the product mixture is toxic to fish. When OPA is neutralized by glycine, forming an Schiffs base (fish safe), the neutralized solution appears dark. New neutralization methods seem essential. NaOH (Cannizzaro reaction) neutralizes OPA. The end product shows no color change and is fish-safe. Hydrogen peroxide also neutralizes CIDEX~(~R) OPA Solution almost instantly at room temperature without color change, and the neutralized solution passes the fish test. Bleach seems as good as hydrogen peroxide but the end product fails pass the fish test. Detailed neutralization mechanisms are discussed.