Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts ...Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.展开更多
A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first sev...A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first several minutes, then gradually slowed down, and atlast did not change any more. The experimental data was well fitted by the Langmuir kineticequation, arid with increasing selenite concentration or decreasing solution pH, the reaction lastedlonger, the maximum of hydroxyl release (x_m) increased, and the binding constant (k) decreased.The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.展开更多
An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining(SPL) generated by the aluminum industry.The combustion mechanisms, evolved gasses, and ash properties of SP...An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining(SPL) generated by the aluminum industry.The combustion mechanisms, evolved gasses, and ash properties of SPL were characterized dynamically in response to the elevated temperature and heating rates.Differential scanning calorimetric(DSC) results indicated an exothermic reaction behavior probably able to meet the energy needs of various industrial applications.The reaction mechanisms for the SPL combustion were best described using the 1.5-, 3-and 2.5-order reaction models.Fluoride volatilization rate of the flue gas was estimated at 2.24%.The SPL combustion emitted CO_(2), HNCO, NO, and NO_(2) but SO_(x).The joint optimization of remaining mass, derivative thermogravimetry, and derivative DSC was achieved with the optimal temperature and heating rate combination of 783.5 ℃, and 5 ℃/min, respectively.Interaction between temperature and heating rate exerted the strongest and weakest impact on DSC and remaining mass, respectively.The fluorine mainly as the formation of substantial NaF and CaF_(2) in the residual ash.Besides,the composition and effect of environment of residual solid were evaluated.The ash slagging tendency and its mineral deposition mechanisms were elucidated in terms of turning SPL waste into a benign input to a circular waste utilization.展开更多
Shaped Mg alloy foams with closed-cell structure are highly interested for a great potential to be utilized in the fields where weight reduction is urgently required.A powder metallurgical method,namely gas release re...Shaped Mg alloy foams with closed-cell structure are highly interested for a great potential to be utilized in the fields where weight reduction is urgently required.A powder metallurgical method,namely gas release reaction powder metallurgy route to fabricate Mg-X(X=Al,Zn or Cu)alloy foams,was summarized.The principles on shaped Mg-X foams fabrication via the route were proposed.In addition,the effects of alloying elements,sintering treatment and foaming temperatures on fabrication of shaped Mg-X alloy foams were investigated experimentally.The results show that the key to ensure a successful foaming of Mg-X alloy foams is to add alloying metals alloyed with Mg to form lower melting(<600℃)intermetallic compounds by the initial sintering treatment.The foaming mechanism of Mg-X alloy foams also has been clarified,that is,the low-melting-point Mg-based intermetallic compounds melt first,and then reactions between the melt and CaCO_(3),a foaming agent,release CO gas to make the precursor foamed and finally shaped Mg-X alloy foam with a promising cellular structure is prepared.This route has been verified by successful fabrication on shaped Mg-Al,Mg-Zn and Mg-Cu foams with cellular structure.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.49971046 and 49831005).
文摘Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.
基金Project supported by the National Natural Science Foundation of China (Nos. 49971046 and 49831005).
文摘A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first several minutes, then gradually slowed down, and atlast did not change any more. The experimental data was well fitted by the Langmuir kineticequation, arid with increasing selenite concentration or decreasing solution pH, the reaction lastedlonger, the maximum of hydroxyl release (x_m) increased, and the binding constant (k) decreased.The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.
基金supported by the National Natural Science Foundation of China(Nos.51978175,22006015)the Social Science and Technology Development Project of Dongguan(No.2019507140211)the Scientific Research Youth Team of Dongguan University of Technology(No.TDQN2019006)。
文摘An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining(SPL) generated by the aluminum industry.The combustion mechanisms, evolved gasses, and ash properties of SPL were characterized dynamically in response to the elevated temperature and heating rates.Differential scanning calorimetric(DSC) results indicated an exothermic reaction behavior probably able to meet the energy needs of various industrial applications.The reaction mechanisms for the SPL combustion were best described using the 1.5-, 3-and 2.5-order reaction models.Fluoride volatilization rate of the flue gas was estimated at 2.24%.The SPL combustion emitted CO_(2), HNCO, NO, and NO_(2) but SO_(x).The joint optimization of remaining mass, derivative thermogravimetry, and derivative DSC was achieved with the optimal temperature and heating rate combination of 783.5 ℃, and 5 ℃/min, respectively.Interaction between temperature and heating rate exerted the strongest and weakest impact on DSC and remaining mass, respectively.The fluorine mainly as the formation of substantial NaF and CaF_(2) in the residual ash.Besides,the composition and effect of environment of residual solid were evaluated.The ash slagging tendency and its mineral deposition mechanisms were elucidated in terms of turning SPL waste into a benign input to a circular waste utilization.
基金supported by National Natural Science Foundation of China(No.51971017)Science Funds for Creative Research Groups of China(51921001)+2 种基金Program for Changjiang Scholars and Innovative Research Team in University of China(IRT_14R05)Projects of SKLAMM-USTB(2018Z-19)the financial support from the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-18-004C1).
文摘Shaped Mg alloy foams with closed-cell structure are highly interested for a great potential to be utilized in the fields where weight reduction is urgently required.A powder metallurgical method,namely gas release reaction powder metallurgy route to fabricate Mg-X(X=Al,Zn or Cu)alloy foams,was summarized.The principles on shaped Mg-X foams fabrication via the route were proposed.In addition,the effects of alloying elements,sintering treatment and foaming temperatures on fabrication of shaped Mg-X alloy foams were investigated experimentally.The results show that the key to ensure a successful foaming of Mg-X alloy foams is to add alloying metals alloyed with Mg to form lower melting(<600℃)intermetallic compounds by the initial sintering treatment.The foaming mechanism of Mg-X alloy foams also has been clarified,that is,the low-melting-point Mg-based intermetallic compounds melt first,and then reactions between the melt and CaCO_(3),a foaming agent,release CO gas to make the precursor foamed and finally shaped Mg-X alloy foam with a promising cellular structure is prepared.This route has been verified by successful fabrication on shaped Mg-Al,Mg-Zn and Mg-Cu foams with cellular structure.
