Zirconium is the not-so-secret ingredient in non-toxic cationic tanning agents that TFL highlighted in the build-up to the Freiberg Leather Days event. Before the conference took place in mid-June, TFL said tests with the new agents showed a significant reduction in the wastewater load at tanneries' effluent treatment plants, with a noticeable reduction in chemical oxygen demand and total dissolved solids, as well as improved biodegradability.
At the conference, Florian Döppert said improvements in the biodegradability of waste from tanneries are necessary and that trials he has conducted using zirconium instead of chrome show that this alternative metal presents "possibilities". But he said: "This is an old story because zirconium has been around a long time. I found many interesting papers on the subject, but they were all too theoretical."
He then recounted his experience of developing "from scratch" processes for tanning and retanning using zirconium. Through trial and error, he found that a masked liquid agent with 22% ZrO2 worked well in retanning and in tanning from pickle.
He concluded: "There is a long way to go before we could talk about full tanning with zirconium, but we could be at the beginning of an interesting development. It would be costly to use it from the start of the tanning process because it would be expensive to use it in the quantities you would need. It makes more sense to use it in smaller quantities in retanning. I am cautiously optimistic."
The quality of the leather he was able to produce during the trials he conducted was, ultimately, good, while at the effluent treatment plant, he achieved a reduction in total dissolved solids and chemical oxygen demand of almost 50%.
Magazine: World Leather June/July 2018