If you use a wire brush as mentioned in other comment, be careful - can scratch the bricks very badly very easily. And, a wire brush will perforate your rubber gloves easily, letting the acid onto your hands. I use this for this kind of job (good for grout/tile cleaning too - the strap is nice on vertical surfaces so it does not fly away every time you catch it on a lip, and have to bend over to pick it up.
BTW - if using acid, especially if stronger than vinegar, you should be wearing goggles (not just glasses) and maybe a face shield too, keep your nose away from the fumes as they can damage your nasal membranes and lungs in concentration, and chemical gloves - you can get them at hardware, home improvement, some paint, some auto supply stores. Regular thin latex gloves will not cut it. Keep a bottle of fresh water (not used for drinking) in close reach, or better yet in a belt holsster, so in case you get acid in/on your eyes or arms or gloves you can flush it out/off immediately.
Personally, I would recommend a stiff horse or floor brush instead if you need to brush it - and be aware the bristles will shoot acid out 5 feet or more, so keep everything in that reach wet and hose off the surrounding acid-misted area when you hose you immediate work area.
BTW - don't get too carried away with the flushing of the wall surface - use a spray rather than heavy flow, because you don't want to flood your basement.