核壳结构KNbO3@Co(OH)2的制备及其活化过一硫酸盐降解帕珠沙星的研究

制备了以KNbO₃为载体材料的Co（OH）₂复合材料并对其进行了详细的表征,分析了材料的组成成分、组成形态进而确定了其为核壳结构形貌的KNbO₃@Co（OH）₂.利用合成的样品作为催化剂活化过一硫酸盐（peroxymonosulfate,PMS）来降解帕珠沙星（pazufloxacin,PZF）,结果表明制备的催化剂对PZF的去除效率显著增加.讨论了不同初始PMS剂量对降解效率的影响,发现随着PMS增加可活化生成更多的硫酸根自由基（sulfate radicals,SO₄^·-）和羟基自由基（hydroxyl radicals,HO^·）来降解PZF,但继续增大PMS用量降解效率未见明显提升.酸性和中性pH值条件下利于反应活化PMS降解PZF,而碱性体系减缓反应,甚至强碱体系更易形成Co（OH）₂沉淀不利于反应体系中活性组分CoOH⁺的形成,大大抑制了催化性能.此外,在体系中加入淬灭剂叔丁醇（tert-Butanol,TBA）或者乙醇（ethanol,ETOH）进行自由基的淬灭实验,结果表明SO₄^·-自由基为体系降解PZF过程中主要贡献的自由基,而HO^·自由基的贡献较少.催化剂具有较好的稳定性5次循环之后仍能在10 min之内完全去除PZF.本研究提出了新的思路为制备其他载体的Co（OH）₂核壳结构提供参考依据,同时将该催化剂结合高级氧化技术应用到水体新兴有机污染物净化领域具有很好的应用前景.     

北部湾南流江流域土地覆盖及生物多样性模拟

以北部湾独流入海河流南流江流域为研究对象,基于研究区2000年和2015年遥感数据解译的土地利用数据以及社会经济等数据,采用CLUE-S模型对未来2030年生态保护情景、自然增长情景以及粮食安全情景的土地利用格局进行了模拟预测,在此基础上采用InVEST模型对流域过去和未来不同情景的生物多样性进行了评估,探讨了流域生物多样性的生境质量和生境退化程度.结果表明：2000~2015年南流江流域建设用地、园地、水域和未利用地呈现出增加趋势,其中建设用地的增幅最大,而耕地和林地减幅最大.流域土地系统中共存在着34种土地网络转移流关系,上游存在24种,中游20种,下游28种,耕地与建设用地、耕地与林地以及林地与园地之间的转换占到流域总土地利用变化的70.74%.CLUE-S模型模拟未来土地利用的Kappa系数达到0.86,表明模型模拟未来情景的土地利用精度满足要求.2000年、2015年、2030年生态保护情景、2030年自然增长情景以及2030年粮食安全情景流域生境质量总得分和平均得分分别为866630,900357,921055,876231,865370和0.7457,0.7747,0.7925,0.7539,0.7466.2030年3种情景的中上游和下游地区生物多样性都呈现出不同程度的改善趋势,而中游地区则表现出退化趋势.     

pH值对亚硝酸盐氧化菌动力学及功能基因的影响

为探究pH值对亚硝酸盐氧化菌（NOB）活性动力学影响,本试验采用序批式活性污泥（SBR）反应器,以富含NOB的活性污泥为对象,基于Monod模型考察不同pH值对NOB活性动力学的影响并进行统计学分析.结果表明,Monod方程可较好地反映不同pH值条件下基质底物浓度对NOB比亚硝态氮氧化速率（SNiOR）的影响,且pH=7.0时动力学参数Ks为（6.167mg/L）,r_max为[1.134g/（g·d）],此时NOB活性最好.利用钟形经验模型进行非线性回归拟合,最大比降解速率（r_max）随pH值的增大呈钟形变化,本试验NOB的最佳pH值为（6.9±0.1）,其中r_max维持在r_opt一半以上的pH值范围（ω）为（3.26±0.4）.以亚硝酸盐氧化还原酶类基因（nxrA、nxrB）为引物,基于荧光定量PCR技术分析结果显示,在不同pH值条件下nxrA基因和nxrB基因拷贝数的变化趋势均与动力学参数（Ks、r_max）的规律一致,且nxrA和nxrB基因在系统的降解过程中起协同作用.     

MnCeOx/沸石催化剂对工业典型VOCs的催化性能

以沸石为载体制备了锰铈复合氧化物催化剂（记为:MnCeO_x/沸石催化剂）,探究了催化剂对工业典型VOCs的二元催化性能,并对催化剂进行BET、XRD及SEM表征。结果表明:Ce的加入,促进了Mn的分散,提高了MnCeO_x/沸石催化剂的活性;当n（Mn）∶n（Ce）为1∶1,负载率为20%,焙烧温度为500℃时,催化剂的活性最高,其对甲苯的起燃温度（T₅₀）和完全燃烧温度（T₉₀）分别为155,255℃;单组分实验中,催化剂对3种有机物均表现出较高活性,转化率达到90%时的反应温度均在275℃以下,其活性顺序为乙酸乙酯>甲苯>丙酮,主要受反应活化能大小及分子极性的影响;二元催化实验中,由于竞争吸附的影响,3种物质的T₅₀和T₉₀较单组分均分别提高了8~13,14~38℃。     

Tuning the fill percentage in the hydrothermal synthesis process to increase catalyst performance for ozone decomposition

The performance of Ce-OMS-2 catalysts was improved by tuning the fill percentage in the hydrothermal synthesis process to increase the oxygen vacancy density. The Ce-OMS-2 samples were prepared with different fill percentages by means of a hydrothermal approach (i.e. 80%, 70%, 50% and 30%). Ce-OMS-2 with 80% fill percentage (Ce-OMS-2-80%) showed ozone conversion of 97%, and a lifetime experiment carried out for more than 20?days showed that the activity of the catalyst still remained satisfactorily high (91%). For Ce-OMS-2-80%, Mn ions in the framework as well as K ions in the tunnel sites were replaced by Ce⁴⁺, while for the others only Mn ions were replaced. O₂-TPD and H₂-TPR measurements proved that the Ce-OMS-2-80% catalyst possessed the greatest number of mobile surface oxygen species. XPS and XAFS showed that increasing the fill percentage can reduce the AOS of Mn and augment the amount of oxygen vacancies. The active sites, which accelerate the elimination of O₃, can be enriched by increasing the oxygen vacancies. These findings indicate that increasing ozone removal can be achieved by tuning the fill percentage in the hydrothermal synthesis process.     

Phosphate recovery with granular acid-activated neutralized red mud: Fixed-bed column performance and breakthrough curve modelling

Granular acid-activated neutralized red mud (AaN-RM) has been successfully prepared with good chemical stability and physical strength. However, its potential for industrial application remains unknown. Therefore, the performance of granular AaN-RM for phosphate recovery in a fixed-bed column was investigated. The results demonstrated that the phosphate adsorption performance of granular AaN-RM in a fixed-bed column was affected by various operational parameters, such as the bed depth, flow rate, initial solution pH and initial phosphate concentration. With the optimal empty-bed contact time (EBCT) of 24.27 min, the number of processed bed volumes and the phosphate adsorption capacity reached 496.95 and 84.80 mg/g, respectively. Then, the saturated fixed-bed column could be effectively regenerated with a 0.5 mol/L HCl solution. The desorption efficiency remained as high as 83.45% with a low weight loss of 3.57% in the fifth regeneration cycle. In addition, breakthrough curve modelling showed that a 5-9-1 feed-forward artificial neural network (ANN) could be effectively applied for the optimization of the fixed-bed adsorption system; the coefficient of determination (R²) and the root mean square error (RMSE) evaluated on the validation-testing data were 0.9987 and 0.0183, respectively. Therefore, granular AaN-RM fixed-bed adsorption exhibits promising potential for phosphate removal and recovery from polluted water.     

干湿法结合工艺回收废弃SCR脱硝催化剂中的钛、钒和钨

利用干湿法结合工艺实现废弃SCR脱硝催化剂中Ti、V和W元素的高效分离和浸出,提出成套废弃SCR脱硝催化剂中Ti、V和W的回收技术。以废弃SCR脱硝催化剂为研究对象,优选Ti、V和W元素最佳浸出工况,研究硫酸溶解法回收TiO₂和有机萃取法回收V₂O₅和WO₃的回收率与纯度。结果表明:酸浸还原浸钒最优工艺条件为温度140℃,液固比30∶1;钠化焙烧浸钨最优工艺条件为煅烧温度750℃,反应物与Na₂CO₃配比（质量比）为1∶1.5,在以上条件下V、W浸出率分别达到97.6%、93.6%。利用硫酸溶解法回收得到的TiO₂产物主要以锐钛矿晶型存在形式,在最佳焙烧温度750℃下,TiO₂回收率达到97.17%,纯度为95.35%。利用有机萃取法回收得到的V₂O₅和WO₃产物的回收率和纯度分别为72.47%、75.43%和93.25%、78.26%。     

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern China.Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the past.There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles.Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop.NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer.It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission greatly.THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH_4 may be an important reason for this phenomenon.Further on-road emission tests, especially CH_4 emission test should be carried out in subsequent research.In addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.     

Role of glycine on sulfuric acid-ammonia clusters formation: Transporter or participator

Glycine(Gly) is ubiquitous in the atmosphere and plays a vital role in new particle formation(NPF).However,the potential mechanism of its on sulfuric acid(SA)-ammonia(A)clusters formation under various atmospheric conditions is still ambiguous.Herein,a(Gly)_x·(SA)_y·(A)_z(z≤x+y≤3) multicomponent system was investigated by using density functional theory(DFT) combined with Atmospheric Cluster Dynamics Code(ACDC) at different temperatures and precursor concentrations.The results show that Gly,with one carboxyl(-COOH) and one amine(-NH_2) group,can interact strongly with SA and A in two directions through hydrogen bonds or proton transfer.Within the relevant range of atmospheric concentrations,Gly can enhance the formation rate of SA-A-based clusters,especially at low temperature,low [SA],and median [A].The enhancement(R) of Gly on NPF can be up to 340 at T=218.15 K,[SA]=10~4,[A]=10~9,and [Gly]=10~7 molecules/cm~3.In addition,the main growth paths of clusters show that Gly molecules participate into cluster formation in the initial stage and eventually leave the cluster by evaporation in subsequent cluster growth at low [Gly],it acts as an important "transporter" to connect the smaller and larger cluster.With the increase of [Gly],it acts as a "participator" directly participating in NPF.     

Adsorption of 17β-estradiol from aqueous solution by raw and direct/pre/post-KOH treated lotus seedpod biochar

Five biochars derived from lotus seedpod(LSP) were applied to examine and compare the adsorption capacity of 17β-estradiol(E2) from aqueous solution.The effect of KOH activation and the order of activation steps on material properties were discussed.The effect of contact time,initial concentration,p H,ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process.Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20 hr.The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength.E2 adsorption on LSP-derived biochar(BCs) was influenced little by humic acid,and slightly affected by the solution p H when its value ranged from 4.0 to 9.0,but considerably affected at p H 10.0.Low environmental temperature is favorable for E2 adsorption.Chemisorption,π–π interactions,monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms.Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material.Post-treated biochar exhibited better adsorption capacity for E2 than direct treated,pretreated,and raw LSP biochar.Pyrolyzed biochar at higher temperature improved E2 removal.The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution,with its advantages of good efficiency and simple technology.