Synthesis and adsorption characteristics of grafted hydrazinyl amine magnetite-chitosan for Ni(II) and Pb(II) recovery. Abstract:The sorption properties of a functionalized magnetic chitosan sorbent have been investigated for the recovery of Ni(II) and Pb(II) from aqueous solutions. This material was prepared by one-pot co-precipitation of chitosan with formation of magnetic core, followed by a series of grafting step to immobilize hydrazinyl amine derivative at the surface of chitosan layer. The physico-chemical characteristics of this composite material were investigated using FTIR, XRD, thermogravimetric, titration, elemental analyses. In a second step, the sorbent was tested for heavy metal sorption on synthetic solutions through the study of pH effect, sorption isotherms and uptake kinetics, selective sorption (in function of pH), metal desorption and sorbent recycling. Sorption isotherms were modeled using the Sips equation while the uptake kinetics was fitted by the pseudo-second order rate equation. The sorption capacity reached 4.3 mmol Ni g -1 and 2.5 mmol Pb g -1 but the sorbent was more selective to Pb(II) over Ni(II), especially in acidic conditions. The decrease in sorption capacity at the fifth cycle does not exceed 8 %. In the final step of the study, the sorbents were successfully applied for metal recovery from multi-metal synthetic solution and from a contaminated stormwater collected in a local mining area.

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SUMMARYUsing different ethanol-gasoline fuel blends, a VARICOMP engine was used to study the effect of varying the compression ratio on SI engine performance. The performance tests were carried out using different percentages of ethanol in gasoline fuel, up to 40%, under variable compression ratio conditions. The results show that the engine indicated power improves with the percentage addition of the ethanol in the fuel blend. The maximum improvement occurs at 10% ethanol-90% gasoline fuel blend.

The sorption process is fast (30-40 min equilibrium time).• At pH eq~4 , the maximum sorption capacity reaches 2.68 mmol Sc g −1 .• Rare earth elements totally desorbed using HCl/CaCl 2 , with good sorbent recycling.• REEs strongly enriched onto S-A L PEI after the treatment of a red mud solution.