Efficient photoreductive decomposition of N-nitrosodimethylamine by UV/iodide process.

•N-nitrosodimethylamine (NDMA) was effectively decomposed by UV/iodide process.•NDMA was completely converted to nontoxic end products by UV/iodide process.•The photoreductive process was mainly attributed to the attack of hydrated electrons on the photoexcited NDMA.•The elimination of toxic intermediates was greatly enhanced as pH increased, but its effect on NDMA removal was negligible.