亚微米-乳化含油废水处理Nano submicrometer-emulsion oily wastewater treatment inspired by plant transpiration.docx

Nano/submicrometer-emulsion oily wastewater treatment inspiredby plant transpiration植物蒸腾启发纳米/亚微米-乳化含油废水处理Wang et al., Matter 4, 1274-1286. April 7, 2021 a 2021 Elsevier Inc. s:/doi.org/HIGHLIGHTS 重点LightVapor outClean waterA device with a purification efficiency of >99.7% for nano/submicrometer emulsionsFresh water could be obtained in one step from oily emulsions based on the deviceNano/submicrometer-emulsion oily (sea)water and acid-base corrosion water were purified 一种纳米/亚微米乳化净化效率>99.7%的装 置基于该装置可用含油乳化一步法制取淡水纳米/亚微米乳化油(海)水和酸-碱腐蚀水净化Inspired by plant transpiration, a solar-driven purification device was developed based on wood, poly(vinyl alcohol), and hydroxylated multiwalled carbon nanotubes. By combining superwettability, a porous structure, and a high light adsorption, the device can completely purify nano/submicrometer-emulsion oily water, oily seawater, and acid-base-corrosion oily water under illumination, accomplishing the one-step production of fresh water from oily wastewater.受植物蒸腾作用的启发，基于木材、聚乙烯醇和羟基化多壁碳纳米管，开发一种太阳 能驱动净化装置。结合了超润湿性、多孔结构和高度光吸收，这一装置在光照下可彻底净 化纳米/亚微米乳化含油水、含油海水、酸-碱腐蚀含油水，实现一步由含油废水产淡水。Progress and potential进展和可能The ever-increasing discharge of oily wastewater from domestic activities, industrial processes, and frequent spill accidents poses a serious threat to the safety of drinking water, the ecological environment, marine organisms, and human health. To handle nano/submicrometer emulsions and wastewater containing acid, alkali, and salt ions, inspired by plant transpiration,wood-PVA-CNT. In comparison with the low absorption of wood-PVA wood-PVA-CNTshows high absorption of >93% in the visible and infrared regions. (D) The temperature changes of wood-PVA and wood-PVA-CNT under 1 sun irradiation as a function of time.装置的外表润湿性、吸收和外表温度(A)木材、木材PVA、木材CNT和木材PVACNT表 面的水CAs,显示超亲水性，水CA为0。，说明所有样品为超亲水。(B)木材外表硅 油、大豆油、十六烷、正癸烷和正辛烷的水下CAs分别为146.1±2.9。、145.9±3.2。、146.7±2.0。、143.4±2.7。和 146.7±2.2°,木材PVA 外表分另 IJ 为 152.7±2.6、150.5±1.6°51.2±2.9。、150.1±2.4°和152.2±3.1。，说明PVA填充增强水下疏油性。(C)木材PVA和木材PVACNT可见.红外光吸收。与木材PVA的低吸收相比，木材PVACNT显示可见光和红外区域93%的(D)木材PVA和木材PVACNT在1 sun照射下的温度与时间关系。In addition to the investigation of the wetting property, optical characterization was carefully undertaken to study the light absorption capacity of the device. Visibleinfrared (Vis-IR) diffuse reflection and transmittance spectra in Figure S6 show that the light diffuse reflectance of wood-PVA-CNT drops to less than 3.1% after coating the layer of CNTs; further, the light transmittance decreases to approximately 0%, demonstrating a light absorption of 96.9% over the complete solar spectrum (Figure 2C, see Supplemental information for calculation). In contrast, wood-PVA shows stronger light diffuse reflectance and transmittance due to the absence of CNTs (Figure S6). Furthermore, the filling of PVA in wood channels can slightly decrease its light diffuse reflectance and transmittance.除了研究润湿性质，也仔细进行了光学分析，研究装置的光吸收能力。图S6中可见 红外(Vis-IR)漫反射和透射光谱说明，涂覆CNT层后木材-PVA-CNT光漫反射率降至3.1% 以下；另外，透光率降低到大约0%,说明整个太阳光谱光吸收约为96.9% (图2C,计 算见补充信息)。相比之下，由于没有CNT,木材-PVA显示出更强光漫反射率和透射率 (图S6)o另外，木材通道PVA填充略微降低其光漫反射率和透射率。To estimate the photothermal conversion behavior, the surface temperatures of wood-PVA and wood-PVA-CNT were carefully examined in situ under 1 sun irradiation with an IR camera.As shown in Figure S7, the typical IR photographs show that the surface temperature gradually increased with continuous light illumination. The maximum temperature on the surface was determined and plotted as a function of the irradiation time, as shown in Figure 2D. Due to the water saturation, the initial temperatures of wood-PVA and wood-PVA-CNT were low; further, there was no obvious difference between them (24.3 for wood-PVA and 24.4 for wood-PVA-CNT, which are close to the ambient temperature). As expected, the surface temperature rapidly increases once the light source is turned on. After illumination for approximately 10 min, the surface temperatures of wood-PVA and wood-PVACNT reached a steady state. After further illumination for 1 h, the surface temperatures remained steady at 29.0 and 34.1 for wood-PVA and wood-PVA-CNT, respectively. The temperature discrepancy of wood-PVA-CNT before and after the 1 h light illumination was as high as 9.7 , and that of wood-PVA is 4.7; this can be attributed to the efficient light absorption and photothermal conversion capacity of CNTs. Furthermore, the effect of the CNT layer thickness on the surface temperature was investigated. As shown in Figure S8, the three devices with different thicknesses of CNT layers showed similar steady surface temperatures.为了估算光热转换特性，采用IR相机，仔细分析了原位1 sun照射的木材-PVA和木 材-PVA-CNT外表温度。如图S7所示，典型的IR照片显示外表温度随着连续照射逐渐 升高。确定了外表最高温度，绘制为照射时间的函数，如图2D所示。由于水饱和，木材 -PVA和木材-PVA-CNT初始温度较低；另外，之间没有明显差异（木材-PVA为24.3C, 木材-PVA-CNT为24.4C,接近环境温度）。与预期的一样，一旦翻开光源，外表温度迅速 升高。光照约10 min后，木材-PVA和木材-PVACNT外表温度到达稳定状态。进一步光 照lh后，木材-PVA和木材-PVA-CNT外表温度分别保持在29.0和34.1 光照lh前后 木材-PVA-CNT温度差高达9.7,木材-PVA为4.7；这可以归因于碳纳米管的有效光吸 收和光热转换能力。另外，研究了 CNT层厚度对外表温度的影响。如图S8所示，不同 厚度CNT层的二个装置显不出相似的稳定外表温度。As for the superwetting property, the submicrometer porous structure and the efficient light absorption contributed to the solar-driven oily wastewater remediation. The oil/water purification process was carefully implemented to quantitatively characterize the performance. The wood-PVA-CNT device was prewetted with water before being immersed in the oily water, by which a thin layer of water cushion was formed on the interface, further preventing oil droplets from entering the device. 14d,23 First, a Tween 80-stabilized silicone oil-in-water nano/submicrometer emulsion was selected as the model oily water to systematically evaluate the performance of the purification device. As shown in Figure 3A, the size distribution of the obtained emulsion shows that the oil droplet radius was smaller than 500 nm. To estimate the purification rate, the mass of the nano/submicrometer emulsion was monitored in real time with a balance. The time-dependent mass changes of the nano/submicrometer emulsion under various conditions with 1 sun illumination are shown in Figure 3B. The purification rates were obtained from the slopes of the mass change curves. As plotted in Figure 3C, the rates attain a steady stateafter illumination for approximately 10-15 min, which is consistent with the time that is required for the surface temperature to reach a steady state (Figure 2D). Due to the porous structure, the natural wood and wood-PVA samples demonstrated purification rates of 0.77 and 0.86 kg m-2 h respectively. After coating with the CNTs, the purification rates of wood-CNT and wood-PVA-CNT increased to 1.21 and 1.35 kg m-2 h1, respectively, which are 7.1 and 7.9 times higher than that of pure nano/submicrometer emulsion (0.17 kg m 2 h1). It is worth noting that the purification rate of the device based on wood-PVA was higher than that of the device based on natural wood; this is due to the micro/nano porous structure and the strong capillary effect of wood-PVA. Given the purification rate, the wood-PVA-CNT was selected for conducting the following experiment. To estimate the purification performance of wood-PVA-CNT, the total organic carbon (TOC) content in the original silicone oil-in-water emulsion and the collected water was carefully measured. As shown in Figure 3D, the TOC values of the original emulsion and the collected water were 9,832.1 ±299.4 and 13.7±2.1mg L1, respectively, suggesting a purification efficiency of 99.8%.10110Radius (nm)5 0 5 0 52 2 11() 3一SU9£15304560Time (min).03 £.92 S Co.-O.1 (E 出) oueuo-sse2-C 2.0i-A- Emulsion« Wood« Wood-PVAJ Wood-CNT5 Wood-PVA-CNT,'6学*言。“总二 19-仓区0.5. 7(U0.0Emulsion Product Efficiency °D100008000 Lj3 6000& 40001 2000010 20 30 40 50 60Time (min)0 5 0 5 S4.3.1 (7 ZE 6X) etr o (SAOUOOS山 o o o o 19 8 7j & A A- A-A-A-A - AA-AAA0.0 - q015304560Time (min)()AOU ofc山Figure 3. Performance of the solar-driven device for purifying nanoscale oily emulsions (A) Size distribution of nano/submicrometer-scale silicone oil-in-water emulsion. (B and C) (B)Mass changes and (C) purification rates of nano/submicrometer-scale silicone oil-in-wateremulsion over time under different conditions with 1 sun irradiation. (D) Total organiccarbon (left axis) and purification efficiency (right axis) for nano/submicrometer-scalesilicone oil-in-water emulsions. (E) Purification rates of the nano/submicrometer-scalesilicone oil-in-water emulsion over time under different light intensities. (F) Total organiccarbon of the collected water (left axis) and purification efficiency (right axis) towardnano/submicrometer-scale silicone oil-in-water emulsion under different light intensities.With an increase in light intensity, the TOC of the products increases and the purification efficiencies decrease.净化纳米级油乳化的太阳能驱动装置的性能(A)纳米/亚微米级水包 硅油乳化的尺寸分布。（B和C） （B）不同条件下纳米/亚微米级水包硅油乳化1 sun照射 质量变化（B）和（C）净化率随时间的变化。（D）纳米/亚微米级水包硅油乳化总有机碳 （左轴）和净化效率（右轴）。（E）不同光强下纳米/亚微米级水包硅油乳化不同时间净化 率。（F）不同光强下提供的水的总有机碳（左轴）和纳米/亚微米级水包硅油乳化的净化效率（右轴）。随着光照强度的增加，产品的TOC增加，净化效率降低。就超润湿性而言，亚微米多孔结构和高效光吸收有助于太阳能驱动含油废水修复。仔 细实施油/水净化过程，定量分析性能。木材-PVA-CNT用水预润湿后，浸入含油水中之前 先用水润湿，从而在界面上形成一层薄薄的水垫层，进一步防止油滴进入装置。首先，选 择Tween-80稳定的水包硅油纳米/亚微米乳化作为模型含油水，系统评估净化装置性能。 如图3A所示，所得乳化尺寸分布说明油滴半径小于500 nmo为了估算净化率，采用天 平实时监测纳米/亚微米乳化质量。图3B显示不同条件下1 sun光照下纳米/亚微米乳化 随时间变化的质量变化。由质量变化曲线斜率取得净化率。如图3c所示，照射月10-15 min后，净化率到达稳定状态，与外表温度到达稳定状态所需的时间一致（图2D）。由于 多孔结构，天然木材和木材-PVA样品的净化率分别为0.77和0.86kgm-2hL CNTs包 覆后，木材-CNT和木材-PVA-CNT净化率分别提高到1.21和1.35 kg m-2 h-1,分别比纯纳 米/亚微米乳化高7.1和7.9倍（0.17 kg m-2h）。值得注意dl是，基于木材-PVAdl装置的 净化率高于基于天然木材的装置；这是由于木材-PVA的微/纳米多孔结构和强毛细作用。 鉴于净化率，选择木材-PVA-CNT进行以下实验。为了估算木材-PVA-CNT的净化性能, 仔细测量了原始水包硅油乳化和提供的水中总有机碳（TOC）含量。如图3D所示，原乳 化和收集水TOC值分别为9,832.1+299.4和13.7+2.1 mg L1,说明净化效率为99.8%。The light intensity is capable of determining the purification rate and the purification efficiency for the nano/submicrometer-emulsion oily water. Figure 3E depicts the purification rates under different light intensities with respect to illumination time. Specifically, the purification rates increase from 1.35 to 4.61 kg m-2 h-, on increasing the light intensity from 1 to 5 suns, showing that strong light can obviously increase the purification rate. Meanwhile, the TOC content of the collected water obtained under 1, 2, 3, 4, and 5 suns was 13.7±2.1, 13.2±3.5, 38.2±5.8, 238.8±12.3, and 586.2±30.5 mg LI, respectively （Figure 3F）. Correspondingly, the purification efficiencies were 99.8%, 99.8%, 99.6%, 97.5%, and 94.0%, suggesting that the purification performance of the wood-PVA-CNT became slightly worse under strong light illumination, especially for 4 and 5 suns. The above result may be due to the extraction of tiny oil droplets from the emulsion along with the rapid water flux. Considering the purification efficiency, the light intensity of 1 or 2 suns can be used to treat other emulsions.光强能够决定纳米/亚微米级乳化含水的净化率速率净化效率。图3E描述了不同光强 度下净化速率与光照时间。具体地说，光照强度从1增加到5个sun,净化速率率从1.35 增加到4.61 kg m-2 h-',说明强光可以明显提高净化速率。同时，在1、2、3、4和5个 sun 下取得的收集水的 TOC 含量分别为 13.7+2.1> 13.2+3.5> 38.2+5.8> 238.8+12.3 和 586.2±30.5 mgLl(图 3F)。相应的净化效率分另I为 99.8%、99.8%、99.6%、97.5%和 94.0%, 说明木材-PVA-CNT净化性能强光照射下略有下降，尤其4和5个sun。上述结果可能由 于提取了乳化中的微小油滴，以及更快的水通量。考虑净化效率，1或2个sun的光强可 用于处理其他乳化。To verify the widespread applicability of the solar-driven purification device, some other surfactant-stabilized nano/submicrometer emulsions were also prepared and treated under the light intensity of 1 sun; these included Tween 80-stabilized soybean oil-in-water emulsion (oil droplet radius <400 nm), sodium dodecyl sulfate (SDS)-stabilized hexadecane-in-water emulsion (oil droplet radius <400 nm), SDSstabilized n-decane-in-water emulsion (oil droplet radius <300 nm), and SDS-stabilized n-octane-in-water emulsion (oil droplet radius <500 nm) (Figure S9). As shown in Figure 4A, the TOC contents for the original soybean oil-in-water, hexadecane-inwater, n-decane-in-water, and n-octane-in-water emulsions were 10,642.l±520.6, 15,900.5±426.l, 9,485.6±286.5, and 9,865.0±313.4mg L1, respectively. After treatment by the wood-PVA-CNT purification device, the corresponding clean water obtained showed low TOC values of 13.6±3.1, 13.4±3.9, 21.7±2.8, and 25.2±4.0 mg,L". Therefore, the calculated purification efficiencies are 99.9%, 99.9%, 99.8%, and 99.7% for soybean oil-in-water, hexadecane-in-water, n-decane-in-water, and n-octane-in-water emulsions, respectively. The photos in Figure 4B demonstrate that transparent clean water is obtained from the milky emulsions. The high purification efficiency demonstrates that the solar-driven wood-PVA-CNT device can effectively remedy various types of nano/submicrometer-emulsion oily water. As a control, a wood-CNT device was used to treat an n-octane-in-water emulsion (Figure S10), and the collected water from the wood-CNT device possessed a high TOC content of 218.2±28.7mg L”，which wasmuch higher than that of water fromthe wood-PVA-CNT device (25.2±4.0 mg L-1). The above result further confirms that PVA improves the device performance.为了验证太阳能驱动净化装置的广泛适用性，也制备了一些其他外表活性剂稳定的纳 米/亚微米乳化，并在Isun光强下处理；其中包括Tween 80-稳定大豆水包油乳化(油滴半径400 nm）、十二烷基硫酸钠（SDS）-稳定的水包十六烷乳化（油滴半径400 nm）、SDS 稳定的正癸烷-水乳化（油滴半径v300nm）和SDS稳定的水包正辛烷乳化（油滴半径500 nm）（图S9）o如图4A所示，原始大豆水包油、水包十六烷、水包正癸烷和水包正辛烷 乳化的 TOC 含量分别为 10,642.1 ±520.6、15,900.5±426.1、9,485.6 分别为 ±286.5 和 9,865.0±313.4mg L。木材-PVA-CNT净化装置处理后，取得的相应净化水TOC值较低， 分别为13.6±3.1、13.4±3.9、21.7±2.8和25.2±4.0 mgL。因此，计算的水包大豆油、水包 十六烷、水包正癸烷和水包正辛烷乳化的井化效率分别为99.9%、99.9%、99.8%和99.7% 图4B中的照片说明从乳状乳化中取得了透明的清洁水。高净化效率说明太阳能驱动木材 -PVA-CNT装置可有效地修复各种类型纳米/亚微米乳化含油水。作为对照，采用木材-CNT 装置处理水包正辛烷乳化（图S10）,从木材-CNT装置提供的水具有218.2±28.7mg L/高 TOC含量，远高于木材-PVA-CNT装置中的水（25.2±4.0 mg L”。上述结果进一步证实 PVA提高了装置性能。130160<150O140170C 180soybean0：l hexadecane n-decane n-octane6 5 4 3 2 1 0 5 ooooooou1 4(.1 6e)C9UO。Figure 4. The universality of the solar-driven device for purifying oily wastewater (A) TOC content of the nano/submicrometer emulsions and the collected water (left axis) and puriflcation efficiency (right axis) for various nano/submicrometer emulsions. (B) Digital photos of nano/submicrometer-scale emulsions before and after puriflcation. (C) CAs of silicone oil droplets on the wood-PVA surface under different pHs of water. (D) TOC and purification efficiency of the products from the silicone oil-in-water emulsion with different pHs. (E) Ions and TOC content in heavy crude oil-in-seawater emulsion and the product.The black dashed line is the World Health Organization's standard for drinking water, and the red dashed line is the discharge standard for ocean exploitation. The light intensity is 1120113579 11 13pHo (%)AOU9O行山 o o o o O1 9 8 7 6sun.太阳能驱动含油废水净化装置的通用性（A）纳米/亚微米乳化和收集水的TOC含 量（左轴）和各种纳米/亚微米乳化的净化效率（右轴）。（B）纳米/亚微米级乳化净化前 后的数码照片。（C）不同pH的水硅油滴的木材PVA外表CAo （D）不同pH的水包硅油乳化产水的TOC和净化效率。（E）重质海水包油乳化产水中离子和TOC含量。 黑色虚线是世界卫生组织饮用水标准，红色虚线是海洋开发排放