Ordered mesoporous materials for water pollution treatment:Adsorption and catalysis

To meet the growing emission of water contaminants,the development of new materials that enhance the efficiency of the water treatment system is urgent.Ordered mesoporous materials provide opportunities in environmental processing applications due to their exceptionally high surface areas,large pore sizes,and enough pore volumes.These properties might enhance the performance of materials concerning adsorption/catalysis capability,durability,and stability.In this review,we enumerate the ordered mesoporous materials as adsorbents/catalysts and their modifications in water pollution treatment from the past decade,including heavy metals(Hg^(2+),Pb^(2+),Cd^(2+),Cr^(6+),etc.),toxic anions(nitrate,phosphate,fluoride,etc.),and organic contaminants(organic dyes,antibiotics,etc.).These contributions demonstrate a deep understanding of the synergistic effect between the incorporated framework and homogeneous active centers.Besides,the challenges and perspectives of the future developments of ordered mesoporous materials in wastewater treatment are proposed.This work provides a theoretical basis and complete summary for the application of ordered mesoporous materials in the removal of contaminants from aqueous solutions.

Environmental Regulation,Pollution Treatment Productivity,and Industrial Environmental TFP in China

Amidst growing environmental protection intensity by the Chinese government, this paper investigates the effects of environmental regulation on China＇s industrial pollution treatment productivity and environmental TFP. By estimating China＇s pollution treatment productivity between 2001 and 2008 and analyzing environmental regulation intensity and the effects of the relevant factors and pollution treatment productivity using panel data, this paper discovers that （1） pollution treatment productivity contributed a significant share of about 40% to industrial environmental TFP during the investigation period; （2） environmental regulation may not necessarily cause adverse impacts on pollution treatment efficiency and productivity but demonstrates a U-shaped relationship： when the share of pollution treatment cost in industrial value-added is above the range of 3.8%-5.1%, environmental regulation is likely to promote pollution treatment productivity and thus environmental TFP Judging by the estimation result, enhancing environmental protection and expediting the development of ecological civilization are conducive to China ＂s economic transition towards an intensive, efficient, circular, and sustainable development pattern. China＇s current industrial development has the capacity to tolerate a rather demanding level of pollution treatment and management and China needs to further rely on energy conservation and the environmental production industries to promote the progress of pollution treatment technologies.

Oxidative Degradation of 2,4,6-Trichlorophenolin the Presence of Air Ions

2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.

Kinetic Adsorption of Cd onto Nanometer Al_2O_3/Carbon Fibre

A new nanometer material, nano-Al2O3 with carbon fibre as the carrier, was employed for the removal of Cd with low concentrations from polluted water. The characterization of the material was carried out by means of SEM and TEM. Batch adsorption and elution experiments were carried out to determine the adsorption properties of Cd on the new adsorbent. The classical Thomas model was applied to estimating the equilibrium coefficients of Cd adsorption and the saturated adsorption ability. The results show that the Thomas model is fit for describing the kinetic adsorption process, and the maximum adsorption capacity of the nanometer Al2O3/carbon is 69.29 mg/g. The resulting information also indicates that the desorption of Cd eluted with de-ionized water at a rate of 9.8 mL/min can be neglected. With the advantage of a high adsorption capacity for removing low concentration Cd, the Al2O3/carbon fibre possesses the potentiality to be an effective adsorbent for the removal of Cd from polluted water.

Nanodiamond:a promising metal-free nanoscale material in photocatalysis and electrocatalysis

Benefiting from its surface-rich functional groups,eco-friendliness,impressive electrochemical properties,excellent light absorption,structural tunability at the atomic/morphological level,and ultra-high stability under harsh conditions,nanodiamond has emerged as a promising carbon-based non-metallic material in the field of energy conversion such as electrocatalysis and photocatalysis.Furthermore,nanodiamond,as a new generation of green catalysts,can overcome the poisoning of catalysts by complex pollutants in advanced oxidation processes,thus effectively removing organic matter from water,which is unparalleled in reducing the cost of water purification and avoiding secondary cross-contamination of water by traditional heavy metal-based catalysts.Here,we review the research and development of nanodiamonds as major electrocatalysts and photocatalysts for energy conversion and for air/water treatment for environmental remediation.The relevant properties,trimming strategy,mechanistic understanding,and design principles of nanodiamond as a catalyst are described,as well as the challenges and prospects of this emerging field.

Hybrid constructed wetlands for highly polluted river water treatment and comparison of surface-and subsurface-flow cells

A series of large pilot constructed wetland （CW） systems were constructed near the confluence of an urban stream to a larger fiver in Xi＇an, a northwestern megacity in China, for treating polluted stream water before it entered the receiving water body. Each CW system is a combination of surface- and subsurface-flow cells with local gravel, sand or slag as substrates and Phragmites australis and Typha orientalis as plants. During a one-year operation with an average surface loading of 0.053 m3/（m2.day）, the overall COD, BOD, NH3-N, total nitrogen （TN） and total phosphorus （TP） removals were 72.7% ~ 4.5%, 93.4% ＋ 2.1%, 54.0% ＋ 6.3%, 53.9% ~ 6.0% and 69.4% ：t： 4.6%, respectively, which brought about an effective improvement of the fiver water quality. Surface-flow cells showed better NH3-N removal than their TN removal while subsurface-flow cells showed better TN removal than their NH3-N removal. Using local slag as the substrate, the organic and phosphorus removal could be much improved. Seasonal variation was also found in the removal of all the pollutants and autumn seemed to be the best season for pollutant removal due to the moderate water temperature and well grown plants in the CWs.

Evolutionary Game on Oil and Gas Companies' Pollution Treatment

This paper presents a dynamic model of pollution treatment strategies,driven by the bargaining relationships between governments,oil and gas companies and local residents.The results show that government plays a dominating role and government environmental policies have significant impact on other two parties' behavior.To achieve better pollution treatment in the future,we put forward the following suggestions.An improvement in the legal system is required,and the legal enforcement needs to be strengthened.In terms of pollution treatment,responsibilities and obligations of these three parties need to be clearly defined.A wellfunctioned reward and penalties system needs to be established for minimizing the environment damage in the future.

Numerical modeling and performance evaluation of passive convergence-permeable reactive barrier(PC-PRB)

The passive convergence-permeable reactive barrier(PC-PRB)was proposed to address the limitations of traditional PRB configurations.To evaluate the hydraulic and pollutant removal performance of the PC-PRB system,we developed a simulation code named PRB-Trans.This code uses the two-dimensional(2D)finite element method to simulate groundwater flow and solute transport.Case studies demonstrate that PC-PRB technology is more efficient and cost-effective than continuous permeable reactive barrier(C-PRB)in treating the same contaminated plume.Implementation of PC-PRB technology results in a 33.3%and 72.7%reduction in PRB length(L_(PRB))and height(H_(PRB)),respectively,while increasing 2D horizontal and 2D vertical pollutant treatment efficiencies of PRB by 87.8%and 266.8%,respectively.In addition,the PC-PRB technology has the ability to homogenize the pollutant concentration and pollutant flux through the PRB system,which can mitigate the problems arising from uneven distribution of pollutants in the C-PRB to some extent.The L_(PRB)required for PC-PRB decreases as the water pipe length(L_(p))increases,while the H_(PRB)required initially decreases and then increases with increasing L_(p).The effect of passive well height(Hw)on H_(PRB)is not as significant as that of L_(p)on H_(PRB).Overall,PC-PRB presents a promising and advantageous PRB configuration in the effective treatment of various types of contaminated plumes.

High value-added fluorescence upconversion agents-assisted nanosemiconductors for efficient wide spectral response photocatalysis:Exerting energy transfer effect and applications

The design of the photocatalytic materials has made a great of remarkable progress in the area of the enhancement photocatalytic activity,but there are still lots of problems such as wide band gap,low utilization of sunlight,low quantum efficiency and poor stability,which further limit the extensive practical applications.Thus,it is a hot research topic and key scientific problem to be solved that how to design and prepare the catalysts,which can respond to visible and near-infrared light in sunlight.Inspired by efficient nonlinear optical upconversion materials,upconversion-based nanocomposites can indirectly broaden the absorption ranges of semiconductors by co nverting the captured long-band visible and near-infrared incident light into high-energy short-band visible or ultraviolet light,which can be adopted as the promising candidate in wide-spectral-light-activating photocatalytic materials coupling with conventional semiconductors.According to our recent works and literature reports,recent review summarizes the research progress of photocatalytic materials with upconversion effect on photolysis of water for hydrogen production,degradation of organic and inorganic pollutants,reduction of CO_(2) and photodynamic therapy.The prepared nanocomposites can suppress the recombination of electrons and holes,and greatly improve the photocatalytic efficiency by the synergistic effect.It maybe stimulates a great interest in rational design and preparation of efficient full-spectrum photocatalytic systems and their wide application in solar energy conversion.

Charge transfer between biogenic jarosite derived Fe^3＋ and TiO2 enhances visible light photocatalytic activity of TiO2

In this work, we have shown that mining waste derived Fe^3＋can be used to enhance the photocatalytic activity of TiO2. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO2 and biogenic jarosite. Evidence of Fe／O／Ti bonding in the TiO2/jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO2, biogenic jarosite and mechanically mixed sample of jarosite and TiO2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO2 and jarosite derived Fe^3＋as was shown from the EELS and ELNEFS. Generation of OHU was supported by photoluminesence（PL） experiments.

Is sodium percarbonate a good deltamethrin choice in situ remediation of pollution？

In this research, the toxic effects of deltamethrin （DM） on the behavior responses of Zebra fish （Damo rerio） in the characteristic of behavior strength were investigated followed by an assessment of an in situ remediation of the DM pollution using sodium percarbonate. Behavior strength ofDanio rerio was approximately 0.83 in the control group and was slightly higher than 0.83 in the sublethal treatment （0.1 TU （toxic unit））, which suggested that sublethal DM exposure could induce a stimulation effect in 48 h of exposure. In lower DM concentration treatments （0.5 and 1.0 TU）, behavior strength could be inhibited significantly. Behavior responses of Danio rerio showed a gradually increased tendency when they were exposed to higher concentration of DM, and the declining amplitudes of behavior strength changed with the increase of DM concentrations. These results suggested that DM had evident acute toxicity effects on the behavior responses of Danio rerio with a good dose-effect relationship. The in situ remediation of the DM pollution using sodium percarhonate showed that the toxic effect of DM on behavior responses ofDanio rerio could be eliminated even in the highest concentration of DM （5.0 TU）. Meanwhile, the behavior response of Danio rerio in the treatment of sodium percarbonate was the same as in the control, which indicated that sodium percarbonate had no evident toxic effects on the behavior of Daniu rerio in the current concentration. This study suggested that adding sodium percarbonate in situ might be a good way to eliminate the DM toxic effects.