Recyclable Fe3O4@Polydopamine (PDA) nanofluids for highly efficient solar evaporation

Volumetric solar evaporations by using light-absorbing nanoparticles suspended in liquids (nanofluids) as solar absorbers have been widely regarded as one of the promising solutions for clean water production because of its high efficiency and low capital cost compared to traditional solar distillation systems. Nevertheless, previous solar evaporation systems usually required highly concentrated solar irradiation and high capital cost, limiting the practical application on a large scale. Herein, for the first time in this work, polydopamine (PDA)-capped nano Fe3O4 (Fe3O4@PDA) nanofluids were used as solar absorbers in a volumetric system for solar evaporation. The introduction of organic PDA to nano Fe3O4 highly contributed to the high light-absorbing capacity of over 85％in wide ranges of 200–2400 nm because of the existence of numerous carbon bonds and pi (π) bonds in PDA. As a result, high evaporation efficiency of 69.93％under low irradiation of 1.0 kW m-2 was achieved. Compared to other nanofluids, Fe3O4@PDA nanofluids also provided an advantage in high unit evaporation rates. Moreover, Fe3O4@PDA nanofluids showed excellent reusability and recyclability owing to the preassembled nano Fe3O4, which significantly reduced the material consumptions. These results demonstrated that the Fe3O4@PDA nanofluids held great promising application in highly efficient solar evapo-ration.     

城市臭氧污染特征与高影响气象因子：以苏州为例

近年来城市臭氧(O₃)污染问题日益突出,影响O₃污染的关键气象因子尚不明确,因此分析典型城市——苏州的O₃污染特征,探究O₃污染的高影响气象因子,对该区域大气污染防治具有重要意义.基于苏州环境监测中心2015～2020年4～9月逐小时O₃浓度数据及同期气象观测资料,应用相关分析和机器学习方法对其开展相关分析研究.结果表明：(1) 6年间O₃污染高发季,O₃污染超标率均达20%以上,O₃污染日数和以O₃为首要污染物的污染日数占比均逐年上升,O₃污染问题日益凸显;(2) O₃浓度存在单峰日变化特点,谷值出现在07:00前后,峰值出现在15:00～16:00;其与气温和太阳辐射能的日内变化趋势较一致,但其浓度峰值出现时刻又滞后于二者. 2017年和2019年O₃有典型的“周末效应”,周末较高的太阳辐照度对O₃浓...     

凹凸棒负载TiO2对偶氮染料和纺织废水光催化脱污

通过浸渍的方法 ,制备了天然粘土矿石凹凸棒负载的P2 5TiO2 固化催化剂 .实验了催化剂的负载量和煅烧温度对催化剂活性的影响 .研究了最佳固化催化剂对 5种生物难降解的偶氮染料和纺织废水的太阳光催化脱污 .结果证实该固定化催化剂能利用太阳能光催化脱污偶氮染料及毛纺织废水 ,而且具有高的稳定性 ,可重复使用     

红外掩日遥感监测炼油厂非甲烷烷烃排放通量

采用红外掩日通量遥感监测(SOF)技术分别在2014年5月~2015年12月和2021年10月监测了我国7座大型炼油厂(其中6座原油年加工量均超过1000万t)非甲烷烷烃排放通量(kg/h)及分布.每座炼油厂监测3~8d,测量18~73次,总计获得328个排放通量测量数据,根据国内炼油厂VOCs排放烟羽中非甲烷烷烃质量分数估算了VOCs排放量,结合监测期间实际原油加工量计算了非甲烷烷烃和VOCs排放系数.结果显示:7座炼油厂2014~2015年的非甲烷烷烃排放系数测定值为0.016%~0.11%,平均为0.081%;VOCs排放系数估算为0.020%~0.14%,平均为0.10%.无组织排放约占炼油厂非甲烷烷烃排放总量的70%以上,其中轻油贮罐排放占比过半.国内7座炼油厂2014~2015年非甲烷烷烃排放系数的最好水平与美国南加州6座炼油厂同期SOF监测的最好水平相当,但非甲烷烷烃排放系数的平均水平约为其平均水平的3.9倍,国内炼油厂的VOCs排放控制水平更加参差不齐.国内1座千万吨级炼油厂2021年监测的非甲烷烷烃排放通量和排放系数分别较2015年削减72.4%和74.2%.SOF可为石化VOCs无组织排放监测、量化和排放清单修订提供最佳实用技术,本研究结果提供了国内石化行业VOCs综合整治初期典型炼油厂非甲烷烷烃和VOCs的基线排放实测数据,以及1座千万t级炼油厂6a后治理攻坚效果.