Sorry to hear about your friend's injuries. Hope is on the mend and soon will be well again.
Depending upon severity level of burns bed linen and other textiles that come in contact with burn victims would be sterilized in an autoclave. Same as things used in OR, Labor and Delivery, nursery, and few other areas. You obviously aren't going down that route, so "sterilizing" is out, and sanitizing is in...
When relying upon thermal action for sanitizing hospital linen general recommendation by CDC is 71 C (160 F) for a minimum of 25 minutes. Laundries might break this down into two wash cycles of about 12 minutes each (excluding mixing time). Other sources recommend 70–80°C X 10 min) [158–176°F].
Unless washing linen known to infected, heavily soiled or fouled chemical may not be needed if above temps are followed. Especially if using proper detergent that either contains oxygen bleach (activated is better), or same is added as a "booster". Hydrogen peroxide and or peracetic acid are strong sanitizers, one or both are what many laundries use more and more today instead of chlorine bleach for several reasons.
It will difficult to use chlorine bleach in domestic environment to sanitize linens (or anything) else because you have to accurately titrate chlorine levels. This requires knowing amount of chlorine in product and of course using an EPA registered chlorine bleach product. Bleaches and sanitizers in commercial use for sanitation of laundry will have dosage worked out either on packet or by chemical rep.
Laundering in hot water as above, using a good detergent with oxygen bleach, then drying in a hot dryer, and or ironing with hot iron/mangle will render linens sanitary enough for normal purposes. If anything more is needed speak with a doctor or professional nurse for recommendations.
Last two (drying and or ironing) actually do a great deal in lowering germ count on laundry. No matter what chemicals are used washing machines themselves harbor "germs". This and certain amount of "germs" will always survive whatever is thrown at them during wash. Heat from drying by mechanical means (again dryer or mangle iron) finishes things off by reducing germ loads further.