High capacity ethidium bromide removal by montmorillonites

Ethidium bromide (EtBr) is commonly used as a reagent to investigate DNA and RNA bonding in biochemistry. However, it is mutagenic and toxic; thus, its removal from the waste solution is of the top priority in lab safety practice. Although many products with high EtBr removal capacities are available on the market, developing new products with low material costs and high removal capacities is still an urgent priority. As the EtBr is in a cationic form Et⁺ balanced by counterion Br in aqueous solution, materials with high cation exchange capacity and large specific surface area may have great potential for efficient EtBr removal, Thus, several montmorillonites (MMTs) were evaluated for their EtBr removal capacity and methods of regeneration in this study. Results showed that both external and internal surfaces of MMTs were effective sorption sites for EtBr with a capacity up to 600mg/g. And the waste-laden materials could be regenerated or safely disposed after incineration at 500 °C for 2 h. As such, further tests on optimization and manufacturing kits or devices for practical EtBr removal in routine lab practice is of engineering priority, should MMTs be further explored as an effective material for EtBr removal.