Some phones allow you to use multiple accounts for some apps, like Facebook (Samsung's newer ones do), or apps like Parallel Space, that allow you to crate a 'secure space' in your phone and clone apps inside. Just do a search on the Play Store and a ton of apps that do that should appear. HOWEVER, not sure if they will allow more than one cloned app, so basically restricting your use to just a couple accounts.
Social Media managers, like HootSuite, also allow for multiple accounts, but not sure if they let you secure certain ones or if they're all within the same app.