Volcanic Activity and Thermal Excitation of Rich-silicon Iron Ore Tailing in Concrete

In order to distinguish the filling effect and volcanic activity and explore the ways motivating the activity of rich-silicon iron ore tailing（IOT）, inert quartz was brought in as the correction standard, the influences of fineness, calcination, thermal curing system and some other factors were investigated by IR, XRD, MIP, and so on microscopic methods. The experimental results show grinding and calcination can only change the amorphous state of SiO2, and IOT do not have volcanic activity in concrete cured under room temperature condition. Thermal curing systems can stimulate the activity of IOT, especially mortar cured by autoclave curing system can consume a large amount of Ca（OH）2 and hard calcium silicate and has a closer structure. When the specific surface area of IOT powder is 800 m^2/kg, and 30% cement is replaced by IOT powder, the mortar strength with IOT powder is even higher than that with cementonly.

KINETICS OF REDUCTION IRON OXIDE IN CaO-SiO_2-Al_2O_3-Fe_tO SLAGS WITH CARBON SATURATED IN MOLTEN IRON

The rate of reducing Fet O in CaO-SiO2-Al2O3-Fet O slags with carbon saturated in molten iron has been determined in a graphite crucible in the temperature range of 1673-1773K. The effects of temperature, slag basicity and FetO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with increasing temperature or FEtO concentration in slags, and the reduction rate has a parabolic relation with the simple basicity or optical basicity of slag, the maximum reduction rate being observed at around CaO/SiO2=1.5 of molten slags. The reduction reaction order is 1. 73 or 1.80, and the reduction activation energy is 299.9 or 295.9 kJ/mol in regard to Fet O weight content or Fet O activity calculated by using regular solution model, respectively. The reduction rate of CaO-SiO2-Al2 O3-Fet O slags with carbon saturated in molten iron is in the range of 0.32-3.48 mol-O/cm2·s.

Weak magnetic field accelerates chromate removal by zero-valent iron

Weak magnetic field（WMF） was employed to improve the removal of Cr（VI） by zero-valent iron（ZVI） for the first time. The removal rate of Cr（VI） was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr（VI） concentration and higher p H. Fe2＋was not detected until Cr（VI） was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr（VI） removal rate and that of Fe2＋release rate in the absence of Cr（VI） at pH 4.0-5.5. These phenomena imply that ZVI corrosion with Fe2＋release was the limiting step in the process of Cr（VI） removal. The superimposed WMF had negligible influence on the apparent activation energy of Cr（VI） removal by ZVI, indicating that WMF accelerated Cr（VI）removal by ZVI but did not change the mechanism. The passive layer formed with WMF was much more porous than without WMF, thereby facilitating mass transport. Therefore,WMF could accelerate ZVI corrosion and alleviate the detrimental effects of the passive layer, resulting in more rapid removal of Cr（VI） by ZVI. Exploiting the magnetic memory of ZVI, a two-stage process consisting of a small reactor with WMF for ZVI magnetization and a large reactor for removing contaminants by magnetized ZVI can be employed as a new method of ZVI-mediated remediation.

Degradation of carbamazepine by MWCNTs-promoted generation of high-valent iron-oxo species in a mild system with O-bridged iron perfluorophthalocyanine dimers

Metal phthalocyanine has been extensively studied as a catalyst for degradation of carbamazepine(CBZ).However,metal phthalocyanine tends to undergo their own dimerization or polymerization,thereby reducing their activity points and affecting their catalytic properties.In this study,a catalytic system consisting of O-bridged iron perfluorophthalocyanine dimers(FePcF16-O-FePcF16),multi-walled carbon nanotubes(MWCNTs)and H2O_(2) was proposed.The results showed MWCNTs loaded with FePcF16-O-FePcF16 can achieve excellent degradation of CBZ with smaller dosages of FePcF16-O-FePcF16 and H2O_(2),and milder reaction temperatures.In addition,the results of experiments revealed the reaction mechanism of non-hydroxyl radicals.The highly oxidized high-valent iron-oxo(Fe(IV)=O)species was the main reactive species in the FePcF16-O-FePcF16/MWCNTs/H2O_(2) system.It is noteworthy that MWCNTs can improve the dispersion of FePcF16-O-FePcF16,contributing to the production of highly oxidized Fe(IV)=O.Then,the pathway of CBZ oxidative degradation was speculated,and the study results also provide new ideas for metal phthalocyanine-loaded carbon materials to degrade emerging pollutants.

Thermodynamic evaluation of reaction abilities of structural units in Fe-C binary melts based on atom-molecule coexistence theory

The reaction abilities of structural units in Fe-C binary melts over a temperature range above the liquidus lines have been evaluated by a thermodynamic model for calculating the mass action concentrations Ni of structural units in Fe-C binary melts based on the atom-molecule coexistence theory （AMCT）, i.e., the AMCT-N/model, through comparing with the predicted activities aR.i of both C and Fe by 14 collected models from the literature at four temperatures of 1833, 1873, 1923, and 1973 K. Furthermore, the Raoultian activity coefficient γC0 of in infinitely dilute Fe-C binary melts and the standard molar Gibbs free energy change △solG%m,Cdis（1）→[C]W[C]=1.0 of dissolved liquid C for forming w[C] as 1.0 in Fe-C binary melts referred to 1 mass% of C as reference state have also been determined to be valid. The determined activity coefficient In γC of C and activity coefficient In TEe of Fe including temperature effect for Fe-C binary melts can be described by a quadratic polynomial function and a cubic polynomial function, respectively.