Preparation of felt-metal supported modified polyvinyl alcohol composite hydrophilic ultrafiltration membrane

A novel technology of preparation of felt-metal supported modified polyvinyl alcohol（PVA） ultrafiltration（UF） membrane was invented, which could avoid the blockage of the holes of support layer and the leakage of the casting solution through the holes of support layer. Felt-metal supported ferric sulfate modified PVA composite UF membranes were prepared by the innovative technology. The results show that the composite membranes are used to treat 1 000 mg/L oil/water emulsion at trans-membrane pressure from 0.25 to 0.45 MPa, the permeate flux is from 36 to 52 L/（m2·h）, and the retention of chemical oxygen demand（COD） is over 92%. The composite membrane resistance increases with the increase of trans-naembrane pressure.

Radiation-induced cross-linking:a novel avenue to permanent 3D modification of polymeric membranes

Membrane fouling is always the biggest problem in the practice of membrane separation technologies,which strongly impacts their applicability,separation efficiency,cost effectiveness,and service lifespan.Herein,a simple but effective 3D modification approach was designed for permanently functionalizing polymeric membranes by directly cross-linking polyvinyl alcohol(PVA)under gamma-ray irradiation at room temperature without any additives.After the modification,a PVA layer was constructed on the membrane surface and the pore inner surface of polyvinylidene fluoride(PVDF)membranes.This endowed them with good hydrophilicity,low adsorption of protein model foulants,and easy recoverability properties.In addition,the pore size and distribution were customized by controlling the PVA concentration,which enhanced the rejection ability of the resultant membranes and converted them from microfiltration to ultrafiltration.The crosslinked PVA layer was equipped with the resultant membranes with good resistance to chemical cleaning by acidic,alkaline,and oxidative reagents,which could greatly prolong the membrane service lifetime.Furthermore,this approach was demonstrated as a universal method to modify PVDF membranes with other hydrophilic macromolecular modifiers,including polyethylene glycol,sodium alginate,and polyvinyl pyrrolidone.This modification of the membranes effectively endowed them with good hydrophilicity and antifouling properties,as expected.

Charged modified tight ceramic ultrafiltration membranes for treatment of cationic dye wastewater

Tight ceramic ultrafiltration membranes have been proven to exhibit good rejection performance for reactive dye wastewater at high temperatures because of their high thermal and chemical resistance.However,the application of ceramic membranes for the treatment of cationic dye wastewater is challenging because of their surface charge.In this study,a ceramic membrane is modified by grafting aminosilane(KH-551)to enhance the positive charge of the membrane surface.The rejection performance of the charged modified ceramic membrane toward the methylene blue solution is significantly improved.The modification substance is bonded to the ceramic membrane surface via covalent bonding,which imparts good thermal stability.The modified ceramic membrane exhibits stable separation performance toward the methylene blue solution.Overall,this study provides valuable guidance for the adjustment of the ceramic membrane surface charge for treating industrial cationic dye wastewater.

Preparation and properties of metal-PVA composite hydrophilic ultrafiltration membranes

Metal-polyvinyl alcohol(PVA) composite ultrafiltration membranes were prepared by coating a certain concentration of PVA solution on metallic fiber sintered membranes. The effects of preparation conditions, such as the coating solution concentration, sequence and times of coating, and heat-treatment on the properties of the composite membranes were studied. The results show that the hole diameter of the composite membrane decreases with the increase of the concentration of PVA, the hole diameter of composite membrane is different when the sequence of coating is different. When the higher concentration of PVA solution is used to coat the metallic membrane for the first time and the other smaller one for the second time, the hole diameter of the composite membrane is relatively small, compared with that of the composite membrane made by the smaller concentration of PVA solution for the first time and the other higher one for the second time. The holes of the composite membrane contract and the stability of the membrane is improved by heat treatment. When metal-PVA composite hydrophilic membranes are used to treat the oil/water emulsion with the concentration of 1 000 mg·L -1 , the retention is from 80% to 90%, and the permeate flux is from 15 L·m -2 ·h -1 to 40 L·m -2 ·h -1 at pressure of 0.2 to 0.3 MPa.

A review on heterogeneous photocatalysis for environmental remediation:From semiconductors to modification strategies

Heterogeneous photocatalysis,an advanced oxidation process,has garnered extensive attention in the field of environmental remediation because it involves the direct utilization of solar energy for the removal of numerous pollutants.However,the application of heterogeneous photocatalysis in environmental remediation has not achieved the expected consequences due to enormous challenges such as low photocatalytic efficiencies and high costs of heterogeneous photocatalysts in large-scale practical applications.Furthermore,pollutants in the natural environment,including water,air,and solid phases,are diverse and complex.Therefore,extensive efforts should be made to better understand and apply heterogeneous photocatalysis for environmental remediation.Herein,the fundamentals of heterogeneous photocatalysis for environmental remediation are introduced.Then,potential semiconductors and their modification strategies for environmental photocatalysis are systematically presented.Finally,conclusions and prospects are briefly summarized,and the direction for the future development of environmental photocatalysis is explored.This review may provide reference directions toward understanding,researching,and designing photocatalytic remediation systems for various environmental pollutants.

Modified PVA-CA blend ultrafiltration membrane by alkali metal chloride

The modified PVA CA blend ultrafiltration membranes were prepared by phase inversion from the casting solutions consisting of polyvinyl alcohol(PVA), cellulose acetate(CA), acetic acid, alkali metal chloride and water. The effects of different concentration of alkali metal chloride on the properties of membranes were investigated. The results show that when the mass fraction of the salt in the casting solution is not greater than 1%, the property of rejection of the alkali metal salt modified ultrafiltration PVA CA blend membrane has little change compared with that of the unmodified PVA CA blend membrane, but the permeation flux is much greater than that of the unmodified membrane under the same operation condition. When the mass fraction of the salt is greater than 1.5%, the permeate flux increases much greater than that of the unmodified membrane, but the property of rejection of the modified ultrafiltration membrane decreases greatly. The results also show that the contact angle of the salt modified PVA CA blend UF membrane decreases but the swelling in water increases with the increment of the mass fraction of alkali metal salts. Furthermore, the NaCl modified PVA CA blend membrane has a slightly lower swelling and a little smaller contact angle of water than the KCl modified PVA CA blend membrane does when the mass fraction of salts is the same.

Enhancing the photocatalytic efficiency by the molecular modification effect derived from pollutant adsorption on highly crystalline BiOBr

The adsorption of pollutants can not only promote the direct surface reaction,but also modify the catalyst itself to improve its photoelectric characteristics,which is rarely studied for water treatment with inorganic photocatalyst.A highly crystalline BiOBr(c-BiOBr)was synthesized by a two-step preparation process.Owing to the calcination,the highly crystalline enhanced the interface interaction between pollutant and c-BiOBr.The complex of organic pollutant and[Bi_(2)O_(2)]^(2+)could promote the active electron transfer from the adsorbed pollutant to c-BiOBr for the direct pollutant degradation by holes(h^(+)).Moreover,the pollutant adsorption actually modified c-BiOBr and promoted more unpaired electrons,which would coupling with the photoexcitation to promote generate more O_(2)^(•-).The molecular modification effect derived from pollutant adsorption significantly improved the removal of pollutants.This work strongly deepens the understanding of the molecularmodification effect from the pollutant adsorption and develops a novel and efficient approach for water treatment.

Psychosocial Stress Modifies the Acute Cardiac Health Effects of Traffic-Related Air Pollution

Previous studies have shown that exposure to black carbon(BC,a tracer of traffic-related air pollution)and psychosocial stress are both associated with adverse cardiac effects,but whether psychosocial stress could modify the cardiac effects of BC is unclear.To investigate the potential modifying effect of psychosocial stress on the associations between acute exposure to BC and typical cardiac health variables,real-time personal 24 h measurements were conducted in a repeated-measure study among adults with elevated blood pressure(high-risk group)and a panel study among normal adults(low-risk group)in China.Measured cardiac health variables included ST-segment depression events,heart rate,and heart rate variability(HRV)variables.Perceived Stress Scale,State Anxiety Inventory and Self-rating Depression Scale were used to assess the recent psychosocial stress status of the participants,and a composite stress index was established based on these scales.Generalized linear mixed-effects model was used to analyze the associations between BC exposure and cardiac health variables and potential effect modification by psychosocial stress.A total of 9724 h measurements among 97 participants in the repeated-measure study and 20224 h measurements among 87 participants in the panel study were included in the final analysis.Acute BC exposure was significantly associated with increased ST-segment depression events and heart rate and decreases in HRV in both studies.The marginal effects of acute BC exposure on most cardiac health variables generally tended to be amplified under higher vs low levels of psychosocial stress in both studies,with the composite stress index apparently modifying the associations of BC exposure with most ST-segment depression events and HRV variables.These findings suggest that psychosocial stress may increase the participants’cardiac susceptibility to BC exposure,which could be helpful for the identification of susceptible individuals in the context of traffic-related air pollution.

Industrial solid wastes to environmental protection materials for removal of gaseous pollutants:A review

The application of industrial solid wastes as environmentally functional materials for air pollutants control has gained much attention in recent years due to its potential to reduce air pollution in a cost-effective manner.In this review,we investigate the development of industrialwaste-based functional materials for various gas pollutant removal and consider the relevant reaction mechanism according to different types of industrial solid waste.We see a recent effort towards achieving high-performance environmental functional materials via chemical or physical modification,in which the active components,pore size,and phase structure can be altered.The review will discuss the potential of using industrial solid wastes,these modified materials,or synthesized materials from raw waste precursors for the removal of air pollutants,including SO_(2),NO_(x),Hg^(0),H_(2)S,VOCs,and CO_(2).The challenges still need to be addressed to realize this potential and the prospects for future research fully.The suggestions for future directions include determining the optimal composition of these materials,calculating the real reaction rate and turnover frequency,developing effective treatment methods,and establishing chemical component databases of raw industrial solid waste for catalysts/adsorbent preparation.

Uncovering the effect of poly(ethylene-co-vinyl alcohol)molecular weight and vinyl alcohol content on morphology,antifouling,and permeation properties of polysulfone ultrafiltration membrane:thermodynamic and formation hydrodynamic behavior

Various hydrophilic poly(ethylene-co-vinyl alcohol)(EVOH)were used herein to precisely control the structure and hydrodynamic properties of polysulfone(PSF)membranes.Particularly,to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol(VOH:73%,68%,56%),the non-solvent-induced phase separation(NIPS)technique was used.Polyethylene glycol was used as a compatibilizer and as a porogen in N,Ndimethylacetamide.Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism.The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism.Accordingly,the addition of EVOH led to an increase in the rheology of the dopes.The resulting membranes exhibited a microporous structure,while the finger-like structures became more evident with increasing VOH content.The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics.Interestingly,the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m^(–2)·h^(–1)·bar^(–1),which was higher than that of pure PSF membranes(171 L·m^(–2)·h^(–1)·bar^(–1)).In addition,PSF/EVOH32 rejected bovine serum albumin at a high rate(>90%)and achieved a significant restoration of permeability.Finally,from the thermodynamic and hydrodynamic results,valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

Catalytic destruction of chlorobenzene over K-OMS-2: Inhibition of high toxic byproducts via phosphate modification

In the process of catalytic destruction of chlorinated volatile organic compounds(CVOCs),the catalyst is prone to chlorine poisoning and produce polychlorinated byproducts with high toxicity and persistence,bringing great risk to atmospheric environment and human health.To solve these problems,this work applied phosphate to modify K-OMS-2 catalysts.The physicochemical properties of catalysts were determined by using X-ray powder diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),hydrogen temperature programmed reduction(H_(2)-TPR),pyridine adsorption Fouriertransform infrared(Py-IR)and water temperature programmed desorption(H_(2)O-TPD),and chlorobenzene was selected as a model pollutant to explore the catalytic performance and byproduct inhibition function of phosphating.Experimental results revealed that 1 wt.%phosphate modification yielded the best catalytic activity for chlorobenzene destruction,with the 90%conversion(T90)at approximately 247℃.The phosphating significantly decreased the types and yields of polychlorinated byproducts in effluent.After phosphating,we observed significant hydroxyl groups on catalyst surface,and the active centerwas transformed into Mn(IV)-O…H,which promoted the formation of HCl,and enhanced the dechlorination process.Furthermore,the enriched Lewis acid sites by phosphating profoundly enhanced the deep oxidation ability of the catalyst,which promoted a rapid oxidation of reaction intermediates,so as to reduce byproducts generation.This study provided an effective strategy for inhibiting the toxic byproducts for the catalytic destruction of chlorinated organics.

新型半导体光催化材料降解水体有机污染物的研究进展

水体中有机污染物的积累给生态环境和人们的健康带来了巨大的危害。光催化技术作为高级氧化法的一种,通过活性物质对污染物进行氧化进而使水体污染物降解为小分子有机物,最终实现污染物的矿化,是一种低廉、高效、绿色环保可持续的治理技术。光催化材料的结构性质影响光催化效果,通过准确改性可提升半导体材料的光催化性能。本文对铋(Bi)基材料、石墨相氮化碳(g-C_(3)N_(4))、金属有机框架材料(MOFs)等不同结构光催化材料降解水体中有机污染物的性能进行了综述,对形貌调控、构建异质结、元素掺杂、缺陷工程等改性手段提高其光催化活性的研究情况进行了总结。最后总结与展望了半导体光催化材料光催化降解有机污染物可能的研究方向和重点。

Modification strategies on 2D Ni-Fe MOF-based catalysts in peroxydisulfate activation for efficient organic pollutant removal

This study reports several modification strategies to optimize and enhance the performance of twodimensional(2D) metal organic frameworks(MOFs)-derived catalysts in peroxydisulfate(PDS) activation.The raw 2D Ni-MOF and 2D Ni-Fe-MOF without modification show poor catalytic activities for PDS activation and high metal ion leaching. The carbonization of 2D MOF can increase the activity of the catalyst but cannot solve the metal leaching problem. The further acid treatment of carbonization products can further improve the catalytic activity and decrease the metal ion leaching. The in-situ growth of2D MOF on graphene oxide(GO) support with subsequent carbonization and acid treatment offers the best performance in PDS activation for organic pollutant removal with low metal ion leaching. Compared with other PDS systems, the Ni-Fe-C-acid/GO system displays much lower catalyst and PDS dosages for p-chloroaniline degradation. This study presents new insights in the modification strategies of 2D MOFbased catalysts in PDS activation.

Amino-functionalized UiO-66-doped mixed matrix membranes with high permeation performance and fouling resistance

For the reduction of bovine serum proteins from wastewater,a novel mixed matrix membrane was prepared by functionalizing the substrate material polyaryletherketone(PAEK),followed by carboxyl groups(C-SPAEKS),and then adding amino-functionalized UiO-66-NH_(2)(Am-UiO-66-NH_(2)).Aminofunctionalization of UiO-66 was accomplished by melamine,followed by an amidation reaction to immobilize Am-UiO-66-NH_(2),which was immobilized on the surface of the membrane as well as in the pore channels,which enhanced the hydrophilicity of the membrane surface while increasing the negative potential of the membrane surface.This nanoparticle-loaded ultrafiltration membrane has good permeation performance,with a pure water flux of up to 482.3 L·m^(-2)·h^(-1) for C-SPAEKS/AmUiO-66-NH_(2) and a retention rate of up to 98.7%for bovine serum albumin(BSA)-contaminated solutions.Meanwhile,after several hydrophilic modifications,the flux recovery of BSA contaminants by this series of membranes increased from 56.2%to 80.55%of pure membranes.The results of ultra-filtration flux time tests performed at room temperature showed that the series of ultrafiltration membranes remained relatively stable over a test time of 300 min.Thus,the newly developed mixed matrix membrane showed potential for high efficiency and stability in wastewater treatment containing bovine serum proteins.

植物油基聚氨酯包膜肥料研究进展

缓释肥包膜材料采用的聚氨酯主要由石油基原料制备,由于石油基聚氨酯成本高、环境风险较大,近年来逐渐被生物基聚氨酯所取代。在众多的生物基材料中,植物油因价格低廉、来源广泛、无毒性、可生物降解等特点,成为缓控释肥料膜材的研究热点。本文分别综述了植物油基多元醇的制备方法,植物油基聚氨酯包膜的分类,植物油基聚氨酯包膜肥料的改性及应用。环氧开环、酯交换反应、氨解法、加氢甲酰化以及臭氧氧化还原是植物油改性制备植物油基多元醇的常用技术手段。丙烯酸酯、环氧树脂、有机硅、氟改性、纳米材料等是植物油基聚氨酯包膜材料改性的常用原料,试验证明植物油基聚氨酯包膜肥料具有减少氨挥发、氮淋溶,提高氮素利用效率的作用。如何提高植物油基聚氨酯交联密度、降低生产成本、深入揭示缓释机理以及扩大在大田试验的应用场景将是今后研究的重点。

纳米纤维素基材料对水中新污染物的处理探讨

新污染物具有毒性、环境持久性、生物累积性等特点,近几年在水中被频繁检测出,对人类健康和生态环境造成潜在威胁,如何去除水中新污染物是当前的研究热点。研究发现,纳米纤维素基吸附材料在新污染物的处理中有很好的吸附效果。文中介绍了纳米纤维素的类别、制备及改性方法,综述了纳米纤维素基材料对水中持久性有机污染物、内分泌干扰物、抗生素及微塑料的去除应用,并提出了今后的研究要点应为不同类型新污染物同时高效地吸附,及吸附后的处理和再生问题。

改性材料用于光催化降解水中多种污染物的研究

随着工业化和城市化进程的加快,水体中污染物种类增多,对生态系统构成威胁。探究金属离子和非金属离子掺杂、贵金属沉积、半导体复合等改性技术以及其在提高光催化剂光吸收范围和光生载流子分离效率方面的作用。结果显示,改性策略能够明显提升材料在可见光下的光催化性能,有效降解包括染料、农药和藻类在内的多种污染物,未来需要关注实际水体中共存污染物的去除以及开发稳定、易回收、循环利用性强的高效光催化剂。

饮用水处理过程中天然有机物引起的超滤膜污染机制研究进展

天然有机物(NOM)存在于地表水、地下水和土壤水中。超滤(UF)膜技术具有运行压力小、设备集成化程度高和占地面积小等优势,但NOM造成的复合污染使超滤膜在水处理的应用管理变得复杂。本文在概述NOM的来源、组成和化学性质的基础上,通过分析不同结构特征的NOM间的相互作用机制,阐述了不同结构特征的NOM的复合膜污染。从离子与NOM络合的影响因素、络合对NOM理化性质的影响等,分析了离子与NOM的复合膜污染。最后,分析了目前研究面临的挑战,并对未来的发展方向进行了展望。

农林废弃物衍生生物炭吸附水中污染物的研究进展

近年来,水中污染物对人类健康的影响引起了人们广泛关注,以农林废弃物等为原料制备的生物炭是一种高效低成本吸附剂,已被用于去除水中污染物。为进一步提高生物炭的吸附性能,有必要对生物炭进行功能化改性。关于改性生物炭吸附去除水中污染物的报道较多,这些研究探索了各种生物炭功能化改性方法,表明不同改性生物炭对不同污染物具有不同的吸附行为和机制。综述了近5年来改性生物炭吸附去除水中污染物的方法,并对改性生物炭吸附剂在未来废水处理中的发展方向进行展望。

锆基凹凸棒土的制备及其对水体中内分泌干扰物去除性能

通过锆改性绿色友好材料凹凸棒土制备锆基吸附材料去除内分泌干扰物,对其进行一系列测试表征。结果表明,在锆基改性材料表面存在具有功能基团ZrO2,其结构稳定,改性后材料的表面积和总孔容积分别提升3.8倍和2.2倍,在pH为1.5时,电位由负变正,该性质的改变有利于对水体中内分泌干扰物的去除。将锆基改性材料用于4种常见的内分泌干扰物(双酚A、17β-雌二醇、17α-雌二醇、己烷雌酚)的吸附去除研究。结果表明,在pH为1.5,吸附剂投加量为15 mg,内分泌干扰物质量浓度为0.5μg·mL^(-1),吸附30 min后去除率可达100%,该材料经过重复利用4次,其对于内分泌干扰物的去除率可达60%以上。4种污染物的吸附过程符合准二级动力学模型和Langmuir等温吸附模型。