Synergistic effects of trace sulfadiazine and corrosion scales on disinfection by-product formation in bulk water of cast iron pipe.

The effects of trace sulfadiazine (SDZ) and cast-iron corrosion scales on the disinfection by-product (DBP) formation in drinking water distribution systems (DWDSs) were investigated. The results show that under the synergistic effect of trace SDZ (10 µg/L) and magnetite (Fe3O4), higher DBP concentration occurred in the bulk water with the transmission and distribution of the drinking water. Microbial metabolism-related substances, one of the important DBP precursors, increased under the SDZ/Fe3O4 condition. It was found that Fe3O4 induced a faster microbial extracellular electron transport (EET) pathway, resulting in a higher microbial regrowth activity. On the other hand, the rate of chlorine consumption was quite high, and the enhanced microbial EET based on Fe3O4 eliminated the need for microorganisms to secrete excessive extracellular polymeric substances (EPS). More importantly, EPS could be continuously secreted due to the higher microbial activity. Finally, high reactivity between EPS and chlorine disinfectant resulted in the continuous formation of DBPs, higher chlorine consumption, and lower EPS content. Therefore, more attention should be paid to the trace antibiotics polluted water sources and cast-iron corrosion scale composition in the future. This study reveals the synergistic effects of trace antibiotics and corrosion scales on the DBP formation in DWDSs, which has important theoretical significance for the DBP control of tap water.

Superhydrophobic Waste Cardboard Aerogels as Effective and Reusable Oil Absorbents.

As the main component of the municipal waste, waste cardboard has caused a host of environmental problems. Therefore, the reasonable disposal of waste cardboard is of great significance to global sustainable development and green economics. Herein, using waste cardboard as the raw material, a superhydrophobic aerogel has been developed with a unique three-dimensional porous network structure, which exhibits excellent selective oil absorption capacities. The aerogel was made by combining Ca2+ cross-links and postmodification with stearic acid. Superhydrophobic aerogels can absorb various organic solutions and its maximum absorption capacity can reach 47 times its own weight. Meanwhile, the size of aerogels has been further expanded, with a diameter of 21.2 cm and a height of 3.2 cm, which can absorb 34 times its own weight of kerosene. More importantly, the aerogel can also absorb oil droplets in oil/water emulsions with an adsorption efficiency of over 98.5%. Moreover, the aerogel can be employed multiple times without significantly reducing the adsorption capacity via distillation or squeezing, depending upon the type of pollutions. Consequently, we believe that these facile and inexpensive superhydrophobic aerogels can effectively adsorb oily wastewater, which matches well with the requirement for environmentally friendliness from the perspective of practical application.

A Universal Strategy for the Preparation of Dual Superlyophobic Surfaces in Oil-Water Systems.

There are some methods to prepare superwetting surfaces with underwater superoleophobicity (UWSOB) or underoil superhydrophobicity (UOSHB), but it is still thorny to put forward a universal strategy for constructing dual superlyophobic surfaces in oil-water systems due to a thermodynamic contradiction. Herein, a universal strategy was proposed to prepare the dual superlyophobic surfaces in oil-water systems only via delicately controlling surface chemistry, that is, adjusting the ratios of superhydrophilic and superhydrophobic counterparts in the spray solution. Three types of materials, attapulgite (APT), TiO2, and loess, were chosen to prepare a diverse series of mixed coatings (mass gradient of superhydrophobic counterparts from 0 to 100 wt %). With the proportion of each superhydrophobic counterpart increasing, the underwater oil contact angle (θo/w*) of each mixed coating slightly decreased but still was more than 150°, that is, UWSOB. In contrast, the underoil water contact angle (θw/o*) was significantly improved, realizing the transformation from UOHL (or UOHB) to UOSHB. More importantly, the respective mass ratios of superhydrophobic counterparts in the resulting mixed coatings of APT, TiO2, and loess were finally determined to be 0.3, 0.4, and 0.2, respectively. Taking APT as a model, a train of mixed APT coatings with different superhydrophobic components were systematically characterized and analyzed. Finally, the prepared superlyophobic separation mesh in oil-water systems was applied to the separation of various surfactant-stabilized oil-water emulsions. We envision that this universal strategy we proposed will show a significant application potential in addressing scientific and technological challenges in the field of interfacial chemistry such as oil-water separation, microfluidics, microdroplet manipulation, antifogging/icing, cell engineering, drag reduction, and so forth.