Effect of Fe(II/III) on tetracycline degradation under UV/VUV irradiation

•VUV/UV was more efficient at degrading TTC than UV by a factor of about 10.•Fe(III) could promote TTC degradation under sole UV (254nm) irradiation.•Fe(II) could facilitate TTC degradation under VUV/UV by potential Fenton process.•Fe(II) and Fe(III) enhanced TTC mineralization under VUV/UV and UV, respectively.•VUV/UV (+Fe(II)) was a cost-effective way for degrading TTC.