Nickel removal by biosorption onto medlar male flowers coupled with photocatalysis on the spinel ZnMn2O4

Ni2+ is a highly toxic above 0.07 mg/l and its removal is of high significance. the biosorption of ni2+ onto medlarmale flowers (mmf) was studied in relation with the physical parameters like ph, contact time, biosorbentdosage, ni2+ concentration and temperature. the interaction biosorbent-ni2+ was examined by the ftirtechnique. the equilibrium was achieved within 40 min and the data were well fitted by the langmuir andredlich-peterson (r-p) models. the maximum ni2+ uptake capacity was 17.073 mg/g at 25°c and the ni2+removal follows a pseudo-second order kinetic with activation energy of 13.3 kj/mol. the thermodynamicparameters: ?s°, ?h° and ?g° showed that the biosorption was spontaneous and endothermic. mmf wasused as a post treatment technique and the biosorption was coupled with the visible light driven ni2+ reductionover the spinel znmn2o4. the effect of the ph, znmn2o4 loading and light intensity on the photoactivity wasinvestigated. 77.5% of ni2+ was reduced after ~140 min under optimal conditions. the ni2+ removal reacheda rate conversion of 96% of with the coupled system biosorption/photocatalysis is very promising for thewater treatment.