涂铁砂吸附镉的动力学研究

研究了10℃,20℃,40℃的温度下,涂铁砂(Iron oxide coated sand,简称IOCS)对镉的吸附动力学。镉在IOCS表面的吸附可分为两个阶段,吸附反应的前60min为快速吸附阶段,60min后,吸附速率明显变慢。温度升高加快了镉在IOCS表面的吸附速率。用Elovich动力学模型,准一级反应模型,准二级反应模型,二级反应模型和粒内扩散动力学模型对实验数据进行回归分析,准二级反应模型能更好地描述镉在IOCS表面的吸附,各吸附模型的模拟优劣顺序为:准二级模型>二级模型>Elovich模型>准一级模型>粒内扩散模型。     

Competitive role of nitrogen functionalities of N doped GO and sensitizing effect of Bi2O3 QDs on TiO2 for water remediation

The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots (BQDs) doped TiO₂ with nitrogen doped graphene oxide (NGO) nanocomposite (NGO/BQDs-TiO₂) was fabricated. It was used for degradation of organic pollutants like 2,4-dichlorophenol (2,4-DCP) and stable dyes, i.e. Rhodamine B and Congo Red. X-ray diffraction (XRD) profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure. The characteristic diffraction peaks of TiO₂ and its composites showed crystalline anatase TiO₂. Morphological images represent spherical shaped TiO₂ evenly covered with BQDs spread on NGO sheet. The surface linkages of $\text{NO}?\mathrm{O}?\text{Ti}$, $\mathrm{C}?\mathrm{O}?\text{Ti}$, $\mathrm{B}\mathrm{i}?\mathrm{O}?\text{Ti}$ and vibrational modes are observed by Fourier transform infrared spectroscopy (FTIR) and Raman studies. BQDs and NGO modified TiO₂ results into red shifting in visible region as studied in diffused reflectance spectroscopy (DRS). NGO and BQDs in TiO₂ are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence (PL) intensities. X-ray photoelectron spectroscopy (XPS) shows that no peak related to $\mathrm{C}?\mathrm{O}$ in NGO/BQDs-TiO₂ is observed. This indicated that doping of nitrogen into GO has reduced some oxygen functional groups. Nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants. Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography (HPLC). Study of radical scavengers indicated that ${\mathrm{O}}_2^{·?}$ has significant role for degradation of 2,4-DCP. Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.     

除草剂对氮肥反硝化损失与N2O排放的影响

在华北平原潮土上,采用原状土柱培养乙炔抑制法研究玉米地氮肥反硝化损失和N2O排放量以及喷施3种除草剂(乙莠、丁莠和旱锄)的影响.结果表明,氮肥的反硝化损失量为2.66kgN/hm2,占施肥量的1.77%;氮肥产生的N2O排放量为3.14kgN/hm2,占施氮量的2.09%,反硝化不是该地区旱作系统氮肥损失的主要途径,但氮肥的施用大大增加N2O排放量.喷施除草剂显著或极显著降低氮肥的N2O排放量和反硝化损失量,比单施尿素处理分别降低2.01~2.85kgN/hm2和2.56~3.16kgN/hm2.     

复合氧化物用于汽车排气催化氧化的实验研究

本文制备出一种非贵金属复合氧化物催化剂 ,可用于治理汽车排气中的 CO和 HC,初步研究了其对 CO和 C3 H6的催化氧化效果 ,实验结果表明 ,该催化剂具有较好的催化氧化能力     

Remediation performance and mechanisms of Cu and Cd contaminated water and soil using Mn/Al-layered double oxide-loaded biochar

The combined pollution of heavy metals is ubiquitous worldwide. Mn/Al-layered double oxide-loaded crab shells biochar (LDO/BC) was prepared, so as to remediate the combined pollution of Cd and Cu in soil and water. The pristine and used LDO/BC were characterized and the results revealed that the layered double oxide was successfully loaded on crab shells biochar (BC) and metal element Ca in crab shells was beneficial to the formation of more regular layered and flake structure. The maximal adsorption capacity (Q_m) of LDO/BC for aqueous Cu²⁺ and Cd²⁺ was 66.23 and 73.47 mg/g, respectively. LDO/BC and BC were used to remediate e-waste-contaminated soil for the first time and exhibited highly efficient performance. The extraction amount of Cu and Cd in the contaminated soil by diethylene triamine penta-acetic acid (DTPA) after treating with 5% LDO/BC was significantly reduced from 819.84 to 205.95 mg/kg (with passivation rate 74.8%) and 8.46 to 4.16 mg/kg (with passivation rate 50.8%), respectively, inferring that the bioavailability of heavy metals declined remarkably. The experimental result also suggested that after remediation by LDO/BC the exchangeable and weak acid soluble Cu and Cd in soil translated to reducible, residual and oxidizable fraction which are more stable state. Precipitation, complexation and ion exchange were proposed as the possible mechanisms for Cd and Cu removal. In general, these experiment results indicate that LDO/BC can be a potentially effective reagent for remediation of heavy metal contaminated water and soil.     

湿法吸收法处理氮氧化物废气

介绍了湿法吸收氮氧化物工业废气的方法，并对吸收液和吸收塔进行了深入的探讨和研究。     

An estimate of the conversion rates of SO_2 to SO_4~(2-)- and NO_2 to HNO_(3+) NO_3~- for the evaluation air pollution in Beijing

The conversion rates of SO2 to SO42- and NO2 to HNO3+NO3- are estimated from the field-data obtained in Beijing in summer, 1988. The results show that the conversion rate of NO2 is about four times as much as that of SO2; The conversion rates have a diurnal variation in a day. On the average, the rate of SO2 is estimated to be 4.7% h-1 during the daytime and 3.4% h-1 during the nighttime. Similarly, the rate of NO2 is estimated to be 17.2% h-1 and 12% h-1 respectively.     

Kinetics of selective catalytic reduction of NO by NH_3 on Fe-Mo/ZSM-5 catalyst

The catalyst of Fe-Mo/ZSM-5 has been found to be more active than Fe-ZSM-5 and Mo/ZSM-5 separately for selective catalytic reduction (SCR) of nitric oxide (NO) with NH_3.The kinetics of the SCR reaction in the presence of O_2 was studied in this work.The results showed that the observed reaction orders were 0.74-0.99,0.01-0.13,and 0 for NO,O_2 and NH_3 at 350-450℃,respectively. And the apparent activation energy of the SCR was 65 kJ/mol on the Fe-Mo/ZSM-5 catalyst.The SCR mechanism was also deduced. Adsorbed NO species can react directly with adsorbed ammonia species on the active sites to form N_2 and H_2O.Gaseous O_2 might serve as a reoxidizing agent for the active sites that have undergone reduction in the SCR process.It is also important to note that a certain amount of NO was decomposed directly over the Fe-Mo/ZSM-5 catalyst in the absence of NH_3.     

O2/CO2气氛下氮反应机理的研究

选取CH4、O2、CO2、Ar、NO、NH3，等气体，作为混合气和煤粉一起送入一维沉降炉内，以模拟O2／CO2气氛下煤中燃料氮、循环NO以及二者的相互作用对NO排放的影响，结果显示，在还原性气氛下NH3、HCN、CH4、CO与循环NO间的反应是NO排放下降的主要因素，且煤焦与NO的异相反应、吸附反应对NO的降解效果要明显高于氧化性气氛，同时，CO2体积分数的增加使得燃料中氮的氧化率升高，循环NO的降解率下降；氧化性气氛下随CO2体积分数的增加，燃料中氮的氧化率也增加，但循环NO的降解率升高．当CO2体积分数不变时，其对NO降解的作用随循环NO体积分数的增加愈加明显，在循环NO也不变且CO2体积分数较低时，随过量空气系数的增加，循环NO的降解率下降，而CO2体积分数较高时则出现相反情况。     

从硬质合金处理渣中回收氧化钴

根据硫酸钠熔炼法处理废合金所得钴渣组成特点 ,通过氧化焙烧、酸分解、水解除杂、沉钴和煅烧等工序制取氧化钴。焙烧最佳工艺条件为 :NaNO3用量为钴渣量的 0 8倍 ,焙烧温度 75 0℃ ,时间 2 5h。盐酸分解、喷淋水解除铁、草酸铵沉钴和煅烧阶段钴的回收率 ( % )分别为 97 5、96 6、99 5和 99 0 ,使Co、Ta的回收率分别达到 92 78%和 85 %。