以城市污水处理厂污泥为原料,采用磷酸活化-微波热解法制备得到污泥活性炭,并将其用于吸附水溶液中的Cr(VI)。分别采用元素分析仪(Vario EL cube)、比表面积孔径分布测定仪(ASAP2020)、扫描电镜(SEM)和傅里叶红外光谱(FT-IR)等仪器对原...以城市污水处理厂污泥为原料,采用磷酸活化-微波热解法制备得到污泥活性炭,并将其用于吸附水溶液中的Cr(VI)。分别采用元素分析仪(Vario EL cube)、比表面积孔径分布测定仪(ASAP2020)、扫描电镜(SEM)和傅里叶红外光谱(FT-IR)等仪器对原污泥及污泥活性炭的表面组成和结构进行表征,探讨污泥活性炭的孔隙结构参数和表面化学性能。通过静态吸附实验,考察了溶液初始pH,接触时间,初始Cr(VI)浓度对污泥活性炭吸附Cr(VI)效果的影响,并探讨了污泥活性炭去除Cr(VI)的机理。实验结果表明,pH越低吸附效果越好,吸附平衡时间为100 h。不同温度下吸附过程均符合Langmuir等温吸附模型,30℃时最大吸附容量为27.55 mg/g;吸附动力学过程符合准二级速率方程(R2>0.99);污泥活性炭对Cr(VI)的去除是一个吸附-还原耦合的过程。展开更多
Pickling sludge generated during the neutralization of pickling wastewater with calcium hydroxide in stainless steel pickling process was characterized using X-ray fluorescence spectrometry, X-ray diffractometry, scan...Pickling sludge generated during the neutralization of pickling wastewater with calcium hydroxide in stainless steel pickling process was characterized using X-ray fluorescence spectrometry, X-ray diffractometry, scanning electron microscopy, thermogravimetry and differential scanning calorimetry, etc. The major compositions of pickling sludge are CaF2, CaSO4, Me（OH）, （M： Fe, Cr, Ni）, and the content of CaF2 is high in the sludge. The melting point of pickling sludge is about 1350℃ and the viscosity is about 0.14 Pa.s at 1450 ℃, which are comparatively lower than those of normal refining slag. After heat treatment, the contents of sulfur and fluorine in the pickling sludge were reduced, confirming the thermal decomposition of sulfate in the sludge. Fluorine in the sludge is reduced by the gaseous SiF4 and A1F3 generated through the reactions of CaF2 with SiO2 and Al2O3. The preliminary results from the reduction test indicate that the sulfur content in the steel is not affected by the presence of sulfur in the sludge. The recovery of nickel is about 40%, and the chromium content changes marginally due to the protective atmosphere under the reduction condition of chromic oxide. The pickling sludge is a potential auxiliary material for the production of stainless steel.展开更多
Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relative...Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relatively easy to control the sludge generation in aluminum alloys.But formation mechanisms and characteristics of sludge in die casting magnesium alloys are still unclear.To ensure the production of high quality die cast components at a low cost,a full understanding of sludge in die casting Mg alloys and its proper control measures need to be developed,since excessive sludge formation affects deleteriously material and operation cost,and casting performance.In the present report,the formation,characteristics and control of Mg die-casting sludge,based on the established knowledge of sludge formation and sludge factor in Al die casting alloys,are reviewed.Previous work on characterization and assessment of sludge in die cast Mg alloys are reviewed.Metallurgical principles for control of sludge in ingot production in association with die casting of Mg alloys are discussed.Rapid assessment of Mg oxide and intermetallics relevant to sludge formation in Mg alloys are highlighted.展开更多
文摘以城市污水处理厂污泥为原料,采用磷酸活化-微波热解法制备得到污泥活性炭,并将其用于吸附水溶液中的Cr(VI)。分别采用元素分析仪(Vario EL cube)、比表面积孔径分布测定仪(ASAP2020)、扫描电镜(SEM)和傅里叶红外光谱(FT-IR)等仪器对原污泥及污泥活性炭的表面组成和结构进行表征,探讨污泥活性炭的孔隙结构参数和表面化学性能。通过静态吸附实验,考察了溶液初始pH,接触时间,初始Cr(VI)浓度对污泥活性炭吸附Cr(VI)效果的影响,并探讨了污泥活性炭去除Cr(VI)的机理。实验结果表明,pH越低吸附效果越好,吸附平衡时间为100 h。不同温度下吸附过程均符合Langmuir等温吸附模型,30℃时最大吸附容量为27.55 mg/g;吸附动力学过程符合准二级速率方程(R2>0.99);污泥活性炭对Cr(VI)的去除是一个吸附-还原耦合的过程。
基金Project(2010JM7010)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,ChinaProject supported by the Technology Foundation for Selected Overseas Chinese Scholars,Department of Human Resources and Social Security of Shaanxi Province,China
文摘Pickling sludge generated during the neutralization of pickling wastewater with calcium hydroxide in stainless steel pickling process was characterized using X-ray fluorescence spectrometry, X-ray diffractometry, scanning electron microscopy, thermogravimetry and differential scanning calorimetry, etc. The major compositions of pickling sludge are CaF2, CaSO4, Me（OH）, （M： Fe, Cr, Ni）, and the content of CaF2 is high in the sludge. The melting point of pickling sludge is about 1350℃ and the viscosity is about 0.14 Pa.s at 1450 ℃, which are comparatively lower than those of normal refining slag. After heat treatment, the contents of sulfur and fluorine in the pickling sludge were reduced, confirming the thermal decomposition of sulfate in the sludge. Fluorine in the sludge is reduced by the gaseous SiF4 and A1F3 generated through the reactions of CaF2 with SiO2 and Al2O3. The preliminary results from the reduction test indicate that the sulfur content in the steel is not affected by the presence of sulfur in the sludge. The recovery of nickel is about 40%, and the chromium content changes marginally due to the protective atmosphere under the reduction condition of chromic oxide. The pickling sludge is a potential auxiliary material for the production of stainless steel.
基金the Meridian Lightweight Technologies Inc., Strathroy, Ontario Canadathe University of Windsor, Windsor, Ontario, Canada for supporting this workpart of a large project funded by Meridian Lightweight Technologies, Inc.
文摘Sludge consisting of heavy element phases and oxides is often generated during the casting operation of aluminum(Al)and magnesium(Mg)alloys.With the help of the well-established Sludge Factor(SF)formula,it is relatively easy to control the sludge generation in aluminum alloys.But formation mechanisms and characteristics of sludge in die casting magnesium alloys are still unclear.To ensure the production of high quality die cast components at a low cost,a full understanding of sludge in die casting Mg alloys and its proper control measures need to be developed,since excessive sludge formation affects deleteriously material and operation cost,and casting performance.In the present report,the formation,characteristics and control of Mg die-casting sludge,based on the established knowledge of sludge formation and sludge factor in Al die casting alloys,are reviewed.Previous work on characterization and assessment of sludge in die cast Mg alloys are reviewed.Metallurgical principles for control of sludge in ingot production in association with die casting of Mg alloys are discussed.Rapid assessment of Mg oxide and intermetallics relevant to sludge formation in Mg alloys are highlighted.
