High-Efficiency Wastewater Purification System Based on Coupled Photoelectric–Catalytic Action Provided by Triboelectric Nanogenerator

It is of great importance to explore a creative route to improve the degradation e ciency of organic pollutants in wastewater.Herein,we construct a unique hybrid system by combining self-powered triboelectric nanogenerator(TENG)with carbon dots-TiO_(2)sheets doped three-dimensional graphene oxide photocatalyst(3 DGA@CDs-TNs),which can significantly enhance the degradation e ciency of brilliant green(BG)and direct blue 5 B(DB)owing to the powerful interaction of TENG and 3 DGA@CDs-TNs photocatalyst.The power output of TENG can be applied for wastewater purification directly,which exhibits a selfpowered electrocatalytic technology.Furthermore,the results also verify that TENG can replace conventional electric catalyst to remove pollutants e ectively from wastewater without any consumption.Subsequently,the unstable fragments and the plausible removal pathways of the two pollutants are proposed.Our work sheds light on the development of e cient and sustainable TENG/photocatalyst system,opening up new opportunities and possibilities for comprehensive utilization of random energy.

A Self-growing Porous Calcium-based Adsorbent Derived from Biowaste for Efficient Wastewater Purification

Traditional adsorbents are normally suffered from a low adsorption capacity that has a finite saturated adsorption capacity. We reported herein a hierarchical self-growing porous calcium silicate hydrate(CSH) that uses biowaste as the precursor and is highly efficient in wastewater purification. In the process of phosphorus removal, CSH can react with phosphorus in water and grow into the hydroxyapatite(HAP). The generation of HAP further increases the active sites while maintains the porous structure of pristine CSH. Subsequently, the HAP could conduct the efficient extraction of Pb^(2+) from wastewater based on the ion exchange between Ca^(2+) and Pb^(2+). Clearly, the CSH structure has self-growing structure using the pollutants as the building blocks, not only achieving high adsorption capacity for pollutants, but also maintaining the hierarchically porous structure that supports the high efficiency in the next cycling. We provide here an intriguing pathway to tackle bottleneck of the traditional adsorbents, i.e., a finite saturated adsorption capacity.

Supramolecular fabrication of hyperbranched polyethyleneimine toward nanofiltration membrane for efficient wastewater purification

Nanofiltration technology has opened an efficient pathway to addressing the grand issue of wastewater purification.Polyethyleneimine(PEI),as a hydrophilic polymer,is a promising material to manufacture separation membranes owing to its superiority.Here,we prepared a hyperbranched PEI-based separation mem-brane through the supramolecular hydrogen bond interaction for wastewater purification.The amino groups in the PEI molecule were partially oxidized to the nitro groups with sodium hypochlorite(NaClO).Moreover,the PEI molecu-lar chains can be regulated from the hyperbranched state to the internal nucle-ation state.Molecular dynamics simulation results further indicated the strong hydrogen bonds among the oxidized PEI(O-PEI)molecular chains and the decreased gyration radius of the O-PEI molecule due to the formation of the nitro groups.In addition,the wettability and zeta potential of O-PEI membranes can be controlled by adjusting the molecular weight and oxidation degree of the PEI molecules.Under the collective effect of size screening and charge repulsion,the O-PEI separation membrane displayed a wide range of purification capabilities for contaminations,such as dye molecules and salts.This work may offer a new strategy to fabricate hyperbranched O-PEI membranes for wastewater purifica-tion.

Recent Applications of Electrocoagulation in Treatment of Water and Wastewater—A Review

During the last two decades, and particularly during the last few years, the environmental sector has shown a largely growing interest in the treatment of different types of water and wastewater by electrocoagulation (EC). The aim of this work was to review studies, conducted mainly during 2008-2011, on the wide and versatile range of feasible EC applications employed in the purification of different types of water and wastewater. The EC applications discussed here were divided into 7 following categories: tannery, textile and colored wastewater;pulp and paper industry wastewater;oily wastewater;food industry wastewater;other types of industrial wastewater;surface water as well as model water and wastewater containing heavy metals, nutrients, cyanide and other elements and ions. In addition, this paper presents an overview of the optimum process conditions (treatment times, current densities, and initial pH) and removal efficiencies (mostly high) achieved for the EC applications discussed. In the vast majority of the studies discussed in this review, the aforementioned values were found to be in the range of 5-60 min (typically less than 30 min), 10-150 A/m2 and near neutral pH, respectively. Both operating costs and electrical energy consumption values were found to vary greatly depending on the type of solution being treated, being between 0.004 -6.74 €/m3 and 0.002-58.0 kWh/m3, but in general they were rather low (typically around 0.1-1.0 €/m3 and 0.4-4.0 kWh/m3).

Solar-driven high-efficiency remediation of wastewater containing small dye molecules

Remediation of wastewater containing dye molecules is necessary to alleviate the significant threat that poses to human health and the environment.Current treatment technologies are seriously limited by their low efficiency for removing small dye molecules or/and inferior regenerability.Herein,we report a bio-inspired,solar-driven,regenerable separation device capable of separating small dye molecules from the wastewater with high efficiency.The device is composed of porous super-hydrophilic ceramic and carbon nanotubes(CNTs).In comparison with previously reported systems,the resultant device not only achieved a highly promising separation efficiency of>99%for dye-containing wastewater,even for small dye molecules(<1.25 nm),but also demonstrated excellent separation stability and strong resistance to acid/alkali.Moreover,the device demonstrated impressive regenerability on simple calcination and re-coating of the CNT layer after it was blocked.This novel separation device shows potential for application in many fields,such as dye separation,wastewater purification and desalination.

Bacillus amyloliquefaciens (IAE635) and their metabolites could purify pollutants, Vibrio spp. and coliformbacteria in coastal aquaculture wastewater

High-density aquaculture often causes the emission of polluted water to the marine environment in the coastal areas of China.To solve the aquaculture-related water quality problems,it is appropriate to adapt eco-friendly methods,such as using microbes and their metabolic products to purify polluted water.In this study,the purifying effects ofBacillus amyloliquefaciens(IAE635)metabolites(poly-γ-glutamic acid;PP)and IAE635 combined with their metabolites(MP)on turbidity,COD,NO3--N,NH4+-N,Vibrio spp.andcoliform bacteria in coastal aquaculture wastewater were conducted in the lab and in situ ponds.The results showed that the removal ofturbidity,COD,NH4+-Nand NO3--Nwith PP and MP was more significant(p<0.05).Compared to Control treatment(Co),the turbidity,COD,NH4+-Nand NO3--N concentrations at 24thhour were evidently reduced by 86.6%,87.5%,83.3%and 58.0%for PP,87.9%,93.5%,86.5%and 78.0%for MP,respectively.The populations of water pathogens under PP and MP were also significantly(p<0.05)removed compared with those of Co;at 24thhour,the Vibriospp.and coliform bacteria were decreased by 68.7%and 66.3%forPP,75.0%and 67.1%for MP,respectively.The water purifying effect of MP was slightly better than that of PP.In situ pond purification test demonstrated that MP significantly lowered the concentrations of turbidity,COD,NH4+-N,NO3--N and NO2--N,which was more effective than EM.A significantly higher(p<0.05)γ-PGA concentration and the total bacterial population for MP compared to PP indicatedthatMPpurifies the coastal aquaculture wastewaterby both flocculation and microbial decomposition.The application of MP will benefit the aquaculture industry by providing a novel method for the removal of chemical pollutants and pathogens.

Study on purification and application of novel precipitant for ceria-based polishing powder

Novel precipitant prepared through carbonation with MgCl2 wastewater generated from rare earth extraction separation process and low-price dolomite as raw materials was studied in this paper. The purification methods of novel precipitant by adding appropriate oxidizing agent were studied. It was found that optimal purification result could be achieved with sodium hypochlorite as iron removal reagent and the iron removal rate could reach up to 90% when the adding amount was 0.1 vol.%. During the preparation, the particle size and distribution of ceria-based polishing powder were affected obviously by the parameters such as concentration, reaction temperature and feeding rate. The results showed that ceria-based polishing powder with D50 =2.5-3.5 μm and the particle size distribution of 0.65-0.75 μm could be prepared when the concentration of CeCl3 was 0.6 mol/L, the reaction temperature was maintained at 50 °C and the feeding speed was controlled at 25 ml/min. Compared with commercial powder, the self-made polishing powder had roughly the same cutting amount, but the surface finish of polished glass was better than that of commercial polishing powder.