Hydrogel 3D network derived and in-situ magnetized Fe@C for activation of peroxymonosulfate to degrade ciprofloxacin

•• Hydrogel supported, confined, derived, in-situ magnetized Fe@C catalyst.•• CIP removal of > 96 % for wide water bodies, at ambient conditions within 60 min.•• Radical (•OH, main SO4•− and O2•−) and non-radical (1O2) in Fe@C/PMS system.•• Four possible pathways and thirteen intermediates in degradation process.•• Potential eco-toxicity of CIP and intermediates to three aquatic organisms.