Facile synthesis of Ag-modified manganese oxide for effective catalytic ozone decomposition

O₃ decomposition catalysts with excellent performance still need to be developed. In this study, Ag-modified manganese oxides (AgMnO_x) were synthesized by a simple co-precipitation method. The effect of calcination temperature on the activity of MnO_x and AgMnO_x catalysts was investigated. The effect of the amount of Ag addition on the activity and structure of the catalysts was further studied by activity testing and characterization by a variety of techniques. The activity of 8%AgMnO_x for ozone decomposition was significantly enhanced due to the formation of the Ag_1.8Mn₈O₁₆ structure, indicating that this phase has excellent performance for ozone decomposition. The weight content of Ag_1.8Mn₈O₁₆ in the 8%AgMnO_x catalyst was only about 33.76%, which further indicates the excellent performance of the Ag_1.8Mn₈O₁₆ phase for ozone decomposition. The H₂ temperature programmed reduction (H₂-TPR) results indicated that the reducibility of the catalysts increased due to the formation of the Ag_1.8Mn₈O₁₆ structure. This study provides guidance for a follow-up study on Ag-modified manganese oxide catalysts for ozone decomposition.     

One-step synthesis of Cu(II) metal–organic gel as recyclable material for rapid, efficient and size selective cationic dyes adsorption

Efficient removal of non-biodegradable and hazardous dyes from wastewater remains a hot research topic. Herein, a rationally designed a Cu(Ⅱ)-based metal–organic gel(Cu-MOG) with a nanoporous 3 D network structure prepared via a simple one-step mixing method was successfully employed for the removal of cationic dyes. The Cu-MOG exhibited high efficiency, with an adsorption capacity of up to 650.32 mg/g, and rapid adsorption efficiency, with the ability to adsorb 80% of Neutral Red within 1 min. The high adsorption efficiency was attributed to its large specific surface area, which enabled it to massively bind cationic dyes through electrostatic interaction, and a nanoporous structure that promoted intra-pore diffusion. Remarkably, the Cu-MOG displayed size-selective adsorption, based on adsorption studies concerning dyes of different sizes as calculated by density functional theory. Additionally, the adsorption performance of the Cu-MOG still maintained removal efficiency of 100% after three regeneration cycles. These results suggested that the Cu-MOG could be expected to be a promising and competitive candidate to conveniently process wastewater.     

产甲烷抑制剂氯仿对污泥厌氧消化中同型产乙酸作用的影响

厌氧消化是城市污泥常用的资源化处理方式,添加产甲烷抑制剂得到的发酵产物乙酸相比于甲烷被认为更具附加值.同型产乙酸途径是污泥厌氧发酵产乙酸途径之一,然而产甲烷抑制剂的存在对其影响尚不明确,这对污泥厌氧发酵产酸工艺的优化和应用至关重要.本文研究了不同氯仿浓度抑制产甲烷条件下挥发性脂肪酸、气体浓度及同型产乙酸菌和总细菌数量的变化,基于乙酸的稳定性碳同位素分馏效应分析了不同温度条件下氯仿对同型产乙酸作用的影响.结果显示,0.1%和0.5%(V/V)氯仿浓度条件下最高乙酸浓度分别为24.5和22.4 mmol·L~(-1),远低于对照组的52.6 mmol·L~(-1).氯仿抑制产甲烷条件下乙酸的稳定碳同位素丰度δ~(13)C值均高于污泥有机质的δ~(13)C值,50℃时乙酸的δ~(13)C值最高,且同型产乙酸菌相对丰度也低于15和30℃条件下.可见,产甲烷抑制剂氯仿同时能够抑制同型产乙酸作用,0.5%浓度下的抑制效果高于0.1%浓度下,且50℃条件下其抑制作用强于15和30℃条件下.     

基于化学损耗矫正的青岛胶州市环境VOCs来源解析

臭氧已成为影响我国环境空气质量的重要污染物之一,准确解析环境臭氧及其前体物VOCs的关键源类及其贡献对于有效防控臭氧污染具有重要作用.因此,利用光化学年龄参数方法估算了青岛胶州市2021年1月1日至2月28日在线VOCs监测数据的初始浓度,矫正环境VOCs物种的光化学损耗;并利用正定矩阵因子分解(PMF)和臭氧生成潜势(OFP)模型进行了环境VOCs及其OFP来源解析研究,以期为青岛市环境臭氧污染的防控提供数据支撑.结果表明,研究期间青岛市环境ρ(TVOCs)和OFP的平均值分别为65.9μg·m^-3和176.7μg·m^-3;其中丙烷浓度(12.4μg·m^-3)和占比(18.9%)最高,而间/对-二甲苯的OFP(24.6μg·m^-3)及占比(13.9%)最高.研究期间TVOCs的初始浓度为153.1μg·m^-3,其光化学损耗率达到63.8%.烯烃是光化学损耗率(92.1%)最高的VOCs物种,其中异戊二烯的光化学损耗率达到98.6%,明显高于其它VOCs物种.基于初始浓度的来源...     

Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.     

汶川地震期间天津地震前兆台网运行与管理

汶川地震发生后,天津市地震局迅速进入应急体制,高效应对突发事件.监测中心、预报中心全体人员坚守岗位,履行职责,较好地完成了汶川地震期间天津地震前兆台网运行监控、数据管理、台站综合评比、数据服务、总结评估等项工作,以无私奉献的团队精神为地震监测预报工作做出了应有的贡献.     

Bioaccumulation of heavy metals by Phragmites australis cultivated in synthesized substrates

Accumulation of heavy metals from various oxides with adsorbed cadmium by wetland plant Phragmites australis was studied to evaluate the fate of heavy metals in the sediment of constructed wetlands. Hoagland solution was used as nutrition supply, and single metal oxide with adsorbed cadmium was applied as contaminant to study the accumulation characteristics of cadmium and the substrate metals by P. australis. After 45-d treatment, the bioaccumulation degree in root followed the order: Al(OH)₃ > Al₂O₃ > Fe₃O₄ > MnO₂ > FeOOH. Heavy metals absorbed by P. australis were largely immobilized by the roots with little translocation to aboveground parts.     

钙镁磷肥对土壤中镉形态转化与水稻吸镉的影响

酸性镉污染水田施用不同用量的钙镁磷肥的田间试验表明:土壤中交换态镉的分配系数随钙镁磷肥用量的增加而降低,呈显著负相关(r,-0.9314);碳酸盐结合态和铁锰氧化物结合态镉的分配系数则呈显著正相关(r,0,9395)。而土壤中有效态镉含量与钙镁磷肥用量则呈显著负相关(r,-0.8853)。镉污染水田一次性投加高量钙镁磷肥后,可使土壤pH显著升高,交换态镉分配系数明显下降,碳酸盐结合态和铁锰氧化物结合态镉分配系数明显升高,导致土壤中有效态镉含量大幅度下降,从而大大减少水稻植株的吸镉量。     

利用脉冲澄清池补充处理生化后废水的运行结果和分析

通过对脉冲澄清池在综合废水处理中运行效果的跟踪分析,确定出利用脉冲澄清池补充处理生化后废水(悬浮物、COD_(cr)、BOD_5等)的影响程度,为其在综合废水处理工艺中的应用及其局限性,提供了必要的参考依据.     

混合基质条件下难降解有机物生物降解性能

选取几种典型的难解解杂环化合物,在混合基质条件下较为系统的地研究了其好氧生物降解性能以及难解有机物间的联合作用效果,研究结果表明,吡啶,喹啉与其同系物类似的生化降解过程及抑制机理,它们的联合作用效果为相加作用,具有不可逆抑制作用物质共存时联合作用效果为协同作用,具有不可逆抑制作用物质与可逆抑制作用物质共存时,联合作用效果为拮抗作用。