finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing

HomeFAQsBooksHelpWantedAdvertiseForum
topic 083

Air emissions from sulfuric acid anodizing


(1995)

Does anyone have information concerning air emissions from sulfuric acid anodizing operations? I've been told that in chromic acid anodize, 80-90% of electrical current is wasted dissociating water molecules creating the mist over the tanks. Is there a similar problem with sulfuric acid anodizing? Thanks

Scott F [last name deleted for privacy by Editor]
Lockheed Martin


(1995)

Let me digress to plating first. Plating processes are not 100 percent "efficient". Some portion of the electrical input goes into laying down metal per Faraday's law, but some percentage liberates hydrogen and oxygen instead. Typical plating processes are maybe 70 to 95 percent efficient, with the notable exception of chrome plating which is about 10-15 percent.

So, almost all plating processes "gas": some very little, some a fair amount, and one (chrome) horribly. In anodizing, there is a somewhat analogous situation, because you want and expect some liberation of hydrogen and oxygen so that the aluminum gets oxidized. The term "efficiency" becomes far less meaningful.

In any event, both chromic and sulfuric anodizing processes gas significantly. The difference is that chromium is a known carcinogen with a long history of causing nasal perforations and chrome ulcerations. But the sulfuric acid is certainly irritating, and all anodizing tanks require local ventilation.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.