焙烧温度对ZnSn水滑石结构及光催化性能的影响

采用共沉淀和热处理法合成了一系列ZnSn-LDHs/MMO光催化剂,利用X射线衍射(XRD)、N2吸附-脱附、傅里叶变换红外(FTIR)、紫外漫反射(UV-Vis-DRS)、光致发光光谱(PL)和电化学阻抗(EIS)等技术对其进行表征,并以甲基橙(MO)为降解物,考察其光催化性能.结果表明,ZnSn-LDHs在焙烧温度...     

磁性LDH负铜催化剂的制备及其对直接青莲D-BL的脱色

实验以滴定共沉淀法制备Mg-Al LDH晶体包覆的Fe3O4颗粒,利用LDH的层间阴离子交换性使其吸附[Cu(C2O4)2]-络合离子,通过焙烧获得磁性焙烧态LDH载体的负铜催化剂。并通过SEM、X-Ray、FT-IR等方法以及静态实验,表征及考察了材料的物化特性及其直接性偶氮染料直接青莲的脱色性能。结果表明,材料对该染料废水有较强去处能力,且磁性良好易于分离回收;其最佳制备条件为用浓度为20 g/L的K2[Cu(C2O4)2]溶液改性一次,反应结束后于450℃下焙烧5 h;上述条件下制备的材料投加量为1 g/L、H2O2浓度为6.53 g/L、处理时间2 h,对200、300和500 mg/L浓度的模拟直接青莲D-BL染料废水去除率分别为99.62%、90.43%和81.92%。     

Effect of TiO2 calcination temperature on the photocatalytic oxidation of gaseous NH3

Carbon-modified titanium dioxide(TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation(PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range( 300℃). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.     

利用铬渣制备重铬酸钠

研究了采用焙烧—硫酸酸化法利用铬渣制备重铬酸钠的工艺.通过L16(44)正交实验得出铬渣焙烧—浸出的最佳工艺条件为:焙烧温度1 000℃,m(碳酸钠)∶m(铬渣)=0.18,液固比4,焙烧时间8h.在此条件下Cr(Ⅵ)回收率为99.3％.硫酸酸化制备重铬酸钠的最佳工艺条件为:浸出液pH为6.6,酸化液pH为3.5,浓缩液中重铬酸钠质量分数为83.1％.此条件下制备的产品重铬酸钠结晶率为44.5％,纯度为99.5％,符合GB1611-92《工业重铬酸钠》的一等品质量标准.处理1t铬渣可制备重铬酸钠约120 kg,增加收入660元.     

木醋调质石灰石煅烧特性试验研究

新型有机钙协同脱硫脱硝技术在实际应用中存在经济代价高的问题,采用木醋废液调质处理石灰石,制得廉价醋酸钙,并对调质产物的煅烧特性进行了研究。X射线衍射分析结果表明,调质石灰石的主要成分为水合醋酸钙,其煅烧过程大致可以分为3个阶段;采用Avrami理论求解调质石灰石的煅烧反应级数,计算结果其反应级数在0.048～0.272较大范围内波动,进一步证明了反应的多阶段性与无定常性。     

A laboratory scale study on arsenic（Ⅴ） removal from aqueous medium using calcined bauxite ore

The present work deals with the As（Ⅴ） removal from an aqueous medium by calcined refractory grade bauxite （CRB） as a function of solution pH, time, As（Ⅴ） concentration and temperature. The residual As（Ⅴ） was lowered from 2 mg/L to below 0.01 mg/L in the optimum pH range 4.0-7.0 using a 5 g/L CRB within 3 h contact time. The adsorption data fits well with Langmuir isotherm and yielded Langmuir monolayer capacity of 1.78 mg As（Ⅴ）/g of CRB at pH 7.0. Presence of anions such as silicate and phosphate decreased As（Ⅴ） adsorption efficiency. An increase temperature resulted a decrease in the amount of As（Ⅴ） adsorbed by 6%. The continuous fixed bed column study showed that at the adsorbent bed depth of 30 cm and residence time of 168 min, the CRB was capable of treating 340 bed volumes of As（V） spiked water （C0 = 2 mg/L） before breakthrough （Ce = 0.01 mg/L）. This solid adsorbent, although not reusable, can be considered for design of adsorption columns as an efficiency arsenic adsorption media.     

两步煅烧法回收芬顿污泥

以芬顿污泥为原料,采用两步煅烧法通过氧化还原作用制备四氧化三铁将铁泥回收。结果表明：污泥中铁元素的转变顺序为羟基氧化铁→氧化铁→四氧化三铁→氧化亚铁→铁单质。芬顿污泥中铁元素主要以羟基氧化铁的形式存在,在第一步400℃煅烧3 h以后,污泥主要成分为氧化铁。在第二步煅烧中,铁的存在形式与加入碳粉后的反应温度关系密切,700℃污泥中的铁主要是以四氧化三铁的形式存在,此时用磁选技术即可将具有磁性的四氧化三铁分离出来,此技术在工艺流程中没有产生废水、危废等物质,过程中的主要材料污泥与碳粉原料简单且完全可回收,减少了二次污染,此技术在工业水处理领域有很好的应用前景。     

Photocatalytic degradation of Acid Blue 62 over CuO-SnO2 nanocomposite photocatalyst under simulated sunlight

The novel CuO-SnO2 nanocomposite oxide photocatalysts were prepared by simple co-precipitation method, and characterized by X- ray diffraction, transmission electron microscopy, N2 adsorption-desorption measurement and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of CuO-SnO2, evaluated using the photodegradation of Acid Blue 62 as a probe reaction under the irradiation of Xenon light, were also found to be related to the calcination temperature and the molar ratio of Cu to Sn. The maximum photocatalytic activity of the CuO-SnO2 photocatalyst was observed to be calcined at 500~C for 3 h （the molar ratio of Cu to Sn was 1：1） due to the sample with good crystallization and high surface area. It also showed much higher photocatalytic activity in treatment dye wastewater under simulated sunlight irradiation compared to Degussa P25 TiO2.     

煅烧结合光辐照提高纳米AgI/TiO_2的可见光响应

为提高AgI/TiO2的可见光响应能力,采用煅烧结合光辐照的工艺对其进行改性.紫外-可见光吸收分析表明,改性AgI/TiO2的敏感光谱范围覆盖了整个可见区,吸收边带从465nm红移至800nm,在500nm处的吸光度提高了近3倍.X-射线衍射分析结果指出,煅烧提高了金红石型TiO2的相对含量,导致禁带宽度从2.89eV降到2.81eV,氙灯辐照进一步增加了锐钛型TiO2、金红石型TiO2和AgI的相对含量,并生成了新的晶体AgCl,使其禁带宽度又降至1.55eV左右.AgCl的产生、AgI和金红石型TiO2相对含量的增加是降低改性材料禁带宽度和增强可见光响应能力的主要原因.研究还表明,只有煅烧后的AgI/TiO2才能通过光辐照来拓宽可见光敏感范围,而且,光辐照中起作用的主要是紫外光,可见光的作用甚小.研究最后提出将2种或2种以上的卤化银负载在纳米TiO2上,更能有效地增强TiO2的可见光响应能力.     

氯化钙焙烧法提取粉煤灰中的氧化铝

研究了以CaCl2为配料对粉煤灰进行焙烧活化,焙烧熟料水洗后,用硫酸溶液浸取以回收粉煤灰中氧化铝的方法,并考察了焙烧温度和时间、CaCl2加量、硫酸浓度和浸取时间等因素对氧化铝回收率的影响.采用添加CaCl2焙烧的方法,可高效率破坏粉煤灰中的刚玉和莫来石,生成能被无机酸分解的物相,如钙铝黄长石、硅铝酸钙等.结果表明,按CaCl2:粉煤灰=0.8的比例加入CaCl2,于900℃焙烧30min,熟料经水洗涤后,按照每g粉煤灰~30mmol硫酸的量加入1~4mol/L的硫酸溶液,常温浸取30min,氧化铝浸出率可达95%以上.