According to IATA, 49 CFR and IMDG, absorbent and cushioning material must be used when transporting liquid hazardous materials.
Regulations state to use absorbents when:
Inner packagings containing liquids must be completely surrounded with a sufficient quantity of absorbent material to absorb the entire liquid contents of the inner packagings.
The outer packaging is intended to contain inner packagings of liquids and is not leakproof; a means of containing any liquid contents in the event of leakage must be provided in the form of the absorbent material being placed inside the means of a leakproof liner or plastic bag.
ICC The Compliance Center offers many options for hazardous material absorbents and cushioning for UN specification packaging such as packing peanuts, absorbent pillows, vermiculite, absorbent pouches, absorbent pads, no dust absorbent pouches, and many more.