Thermodynamic data calculation for iron phases in sulfoaluminate cementitious materials prepared using solid wastes

The preparation of sulfoaluminate cementitious materials(SCM)is a promising way to massively utilize solid wastes.Iron phases are significant in SCM system but the thermodynamic data of some key minerals,such as6 CaO·Al2 O3·2 Fe2 O3(C6 AF2)and 6 CaO·2 Al2 O3·Fe2 O3(C6 A2 F),are missing,which greatly hinders the SCM optimization in a theoretical way.This work,for the first time,calculated the standard formation enthalpy,Gibbs free energy of formation,entropy and molar heat capacity for C6 AF2 and C6 A2 F and lowered the errors to the least with the reference of C4 AF data in the literature.By building the function diagram of Gibbs free energy changes with temperature for the basic iron phase formation reactions with the obtained thermodynamic data,it is proved that the formation likeliness of C6 AF2 is higher than that of C6 A2 F,as is accordant to the literatures and verifies the correctness of obtained data.This work provides a good theoretical foundation to optimize SCM mineral system and to study relevant mechanism deeply.

Synthesis of magnetic carbonaceous acid derived from waste garlic peel for biodiesel production via esterification

Waste biomass-supported magnetic solid acids have particular advantages in catalyst separation.First,a novel magnetic carbonaceous catalyst was synthesized from waste garlic peel(GP)via in situ impregnation before conducting carbonization at 450–600°C and sulfonation at 105°C.The physical and chemical properties of the synthesized catalysts were characterized.It was found that the magnetism of the catalyst increased with the carbonization temperature.The optimized catalyst,carbonized at 600℃(C600-S),possessed an excellent magnetization value of 12.5 emu/g,with a specific surface area of 175.1 m^(2)/g,a pore volume of 0.16 cm^(3)/g,and an acidic property of 0.74 mmol/g-SO3H density.By optimizing the esterification conditions to produce biodiesel,an oleic acid conversion of 94.5%was achieved at w(catalyst dosage)=10%(w is mass fraction),a molar ratio of n(methanol):n(oleic acid)=10:1(n is the amount of substance),and a reaction for 4 h at 90℃.Further,for catalyst regeneration,it was found that sulfuric acid treatment was more effective for improving the esterification activity than solvent washing,with which a conversion of more than 76%was achieved after the third run.