Use a different Firefox profile for work/personal. Sign-in to personal (while at work) to sync bookmarks if firewall allows. Depending on whether you trust you

Use a different Firefox profile for work/personal. Sign-in to personal (while at work) to sync bookmarks if firewall allows. Depending on whether you trust your employer you could sync further personal settings. Don't sign-in to work profile and no work bookmarks or settings/logins get shared. Don't get me wrong: multi-account containers are a blessing for those rare days when you absolutely have to log-in to facebook.