Interaction of engineered nanoparticles with various components of the environment and possible strategies for their risk assessment

Nanoparticles are the materials with at least two dimensions between 1 and 100 nm. Mostly these nanoparticles are natural products but their tremendous commercial use has boosted the artificial synthesis of these particles (engineered nanoparticles). Accelerated production and use of these engineered nanoparticles may cause their release in the environment and facilitate the frequent interactions with biotic and abiotic components of the ecosystems. Despite remarkable commercial benefits, their presence in the nature may cause hazardous biological effects. Therefore, detail understanding of their sources, release interaction with environment, and possible risk assessment would provide a basis for safer use of engineered nanoparticles with minimal or no hazardous impact on environment. Keeping all these points in mind the present review provides updated information on various aspects, e.g. sources, different types, synthesis, interaction with environment, possible strategies for risk management of engineered nanoparticles.     

Behavioural and biochemical responses of two marine invertebrates Scrobicularia plana and Hediste diversicolor to copper oxide nanoparticles

Engineered nano-sized Cu oxide particles are extensively used in diverse applications. Because aquatic environments are the ultimate “sink” for all contaminants, it is expected that nanoparticles (NP) will follow the same fate. In this study, two marine invertebrates Scrobicularia plana and Hediste diversicolor were chosen as ecotoxicological models. The aim was to evaluate behavioural (burrowing kinetics, feeding rate) and biochemical (biomarkers) responses of S. plana and H. diversicolor exposed in the laboratory to Cu (10 μg L⁻¹) added in natural seawater either in the form of engineered nanoparticles (NPs) of CuO or as dissolved Cu in 2% HNO₃. Exposure was characterized by considering (i) the physico-chemical fate of NP (ii) the fraction of labile Cu in experimental media and (iii) Cu bioaccumulation. Results showed high aggregation of CuO NPs in seawater and no additional bioavailable Cu concentrations. Behavioural impairments were observed in S. plana exposed to CuO NPs or soluble Cu whereas in H. diversicolor, only the exposure to soluble Cu led to a burrowing decrease. No obvious neurotoxicity effects were revealed since in both species, no changes in cholinesterasic activity occurred in response to both forms of Cu exposure. Biomarkers of oxidative-stress catalase and glutathione-S-transferase were enhanced in both species whereas superoxide dismutase was increased only in S. plana exposed to CuO NPs. Metallothionein-like protein was increased in bivalves exposed to both forms of Cu. Since, no detectable release of soluble Cu from CuO NPs occurred during the time of experiment, ecotoxicity effects seem to be related to CuO NPs themselves.     

Influence of liberated silver from silver nanoparticles on nitrification inhibition of Nitrosomonas europaea

The ecotoxicity of silver nanoparticles (Ag-NPs) to wastewater biota, including ammonia oxidizing bacteria (AOB), is gaining increasing interest as the number of products containing Ag-NPs continues to rise exponentially and they are expected to accumulate in wastewater treatment plants. This research demonstrated that the addition order of Ag-NP and the media constituents had a profound influence on the stability of the Ag-NP suspension and the corresponding repeatability of results and sensitivity of Nitrosomonas europaea. N. europaea, a model AOB, was found to be extremely sensitive to ionic silver (Ag⁺) and two sizes of Ag-NPs (20 and 80 nm). Ag⁺ exposures resulted in the highest level of toxicity with smaller Ag-NPs (20 nm) being more toxic than larger Ag-NPs (80 nm). The increased sensitivity of N. europaea to smaller Ag-NPs was caused by their higher rates of dissolved silver (dAg) release, via dissolution, due to a greater surface area to volume ratio. dAg was shown to be responsible for the vast majority of the observed Ag-NP toxicity, as determined by abiotic Ag-NP dissolution tests. For the sizes of Ag-NP studied (20 and 80 nm), there appears to be a negligible nanoparticle-specific toxicity. This was further supported by similarities in inhibition mechanisms between Ag⁺ and Ag-NP, with both causing decreases in AMO activity and destabilization of the outer-membrane of N. europaea. Finally, equal concentrations of total silver were found to be tightly associated to both Ag⁺ and Ag-NP-exposed cells despite Ag-NP concentrations being five times greater, by mass, than Ag⁺ concentrations.     

Effect of surfactant-coated iron oxide nanoparticles on the effluent water quality from a simulated sequencing batch reactor treating domestic wastewater

This study was conducted to evaluate the effect of commercially available engineered iron oxide nanoparticles coated with a surfactant (ENP_Fe-surf) on effluent water quality from a lab-scale sequencing batch reactor as a model secondary biological wastewater treatment. Results showed that ∼8.7% of ENP_Fe-surf applied were present in the effluent stream. The stable presence of ENP_Fe-surf was confirmed by analyzing the mean particle diameter and iron concentration in the effluent. Consequently, aqueous ENP_Fe-surf deteriorated the effluent water quality at a statistically significant level (p < 0.05) with respect to soluble chemical oxygen demand, turbidity, and apparent color. This implied that ENP_Fe-surf would be introduced into environmental receptors through the treated effluent and could potentially impact them.     

壳聚糖-CdS复合纳米粒子在光催化降解茜素红中的应用

对壳聚糖-CdS复合纳米粒子在光催化降解茜素红的应用进行研究.结果表明,在2min时茜素红降解效率可达28.6%-82.7%,30min时茜素红降解效率达到71.9%-98.2%;茜素红在光催化降解过程中最大吸收波长261nm处的吸收峰迅速减弱,并最终消失,而在223nm和228nm处分别出现了新的吸收峰,说明茜素红发生了降解;溶液pH值对光催化降解茜素红有一定的影响,在弱酸性条件下降解效率较高;壳聚糖-CdS复合纳米粒子比CdS粒子降解效率高, 2min时降解效率高出24.2%,30min时高出28.4%.     

硼掺杂介孔炭吸附四环素的效能与机制

以椰壳和硼酸为原料,通过简单的一步热解法制备出新型硼掺杂椰壳介孔炭材料（B-CSC）用于水中四环素类污染物的高效吸附去除.系统研究了关键制备条件热解温度和硼碳质量比对其吸附性能的影响,使用比表面积及孔径分析仪（BET）、场发射扫描电镜（SEM）、X射线光子能谱仪（XPS）、拉曼光谱仪（Raman）以及Zeta电位仪（Zeta）对其微观结构及物化性质进行了表征分析.系统考察了初始pH值、不同金属阳离子以及不同背景水质条件对其吸附效果的影响.结合材料表征与相关分析等对其强化吸附机制进行了深入讨论与分析.结果表明,一步热解能够将硼掺入椰壳炭的表面及晶格,导致其拥有更大的比表面积和孔体积,引入硼的形态主要是H₃BO₃、B₂O₃、B和B₄C.B-CSC对四环素的吸附量达到297.65 mg·g^-1,是原始椰壳介孔炭（CSC）的8.9倍.同时,B-CSC对于水环境中常见污染物罗丹明B（RhB）、双酚A（BPA）和亚甲基蓝（MB）的吸附量分别高达372.65、255.24和147.82 mg·g^-1.B-CSC对四环素的吸附过程是物理化学作用共同主导的,主要涉及液膜扩散、表面吸附、介孔与微孔内扩散和活性位点吸附,H₃BO₃是其主要吸附位点.吸附强化机制主要是硼掺杂降低了其碳网络的化学惰性,增强了其与四环素分子的π—π相互作用和氢键作用.     

磁性介孔硅胶萃取剂的制备及萃取性能研究

合成了C18基团修饰的磁性介孔硅胶材料,并利用该材料建立了磁性固相萃取-色谱分析方法,测定了几种环境水样中酞酸酯类(PAEs)污染物的含量.结果表明,该材料具有较大的比表面积(273 m.2g-1)和饱和磁通量(29 emu.g-1),对水样中痕量的PAEs有较强的萃取能力,而且萃取剂的磁分离特性使得萃取操作更为方便、快捷.在优化条件下,30 mg萃取剂在40 min内即可从500 mL水样中萃取痕量PAEs,回收率可达80%以上.此外,该萃取剂在处理复杂环境样品时仍能保持较强的萃取能力,环境水样中4种PAEs的检测限可达15.6—32.5 ng.L-1,加标回收率为62%—109%,相对标准偏差为2%—8%.     

酞菁锌改性介孔分子筛催化降解孔雀石绿

以介孔分子筛MCM-41为载体,采用浸渍法将1,4,8,11,15,18,22,25-八环戊氧基酞菁锌(α-CyOPcZn)负载到分子筛上得到了一种新型的催化剂CyOPcZn/MCM-41.并通过氮气吸附、红外光谱扫描及电镜扫描对催化剂的结构进行表征.考察了该催化剂的用量、H2O2浓度对孔雀石绿降解作用的影响.实验结果表明,在模拟可见光照射下,当催化剂用量0.6 g.L-1、H2O2浓度为0.1 mmol.L-1时,60 min后使0.1 mmol.L-1的孔雀石绿水溶液的脱色率达到98.6%,并呈现出一级反应的动力学特征,速率常数k为0.0891 min-1.催化剂重复使用3次后,脱色率可达96%以上.     

Rapid method for on-site determination of phenolic contaminants in water using a disposable biosensor

A disposable biosensor was fabricated using single-walled carbon nanotubes, gold nanoparticles and tyrosinase (SWCNTs-AuNPs-Tyr) modified screen-printed electrodes. The prepared biosensor was applied to the rapid determination of phenolic contaminants within 15 minutes. The SWCNTs-AuNPs-Tyr bionanocomposite sensing layer was characterized with scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry methods. The characterization results revealed that SWCNTs could lead to a high loading of tyrosinase (Tyr) with the large surface area and the porous morphology, while AuNPs could retain the bioactivity of Tyr and enhance the sensitivity. The detection conditions, including working potential, pH of supporting electrolyte and the amount of Tyr were optimumed. As an example, the biosensor for catechol determination displayed a linear range of 8.0 × 10^-8 to 2.0 × 10^-5 mol·L^-1 with a detection limit of 4.5 × 10^-8 mol·L^-1 (S/N = 3). This method has a rapid response time within 10 s, and shows excellent repeatability and stability. Moreover, the resulting biosensor could be disposable, low-cost, reliable and easy to carry. This kind of new Tyr biosensor provides great potential for rapid, on-site and cost-effective analysis of phenolic contaminants in environmental water samples.     

氧化锌纳米颗粒对膜-生物反应器运行性能的影响

考察了城市污水中典型浓度的氧化锌(ZnO)纳米颗粒对膜-生物反应器(MBR)运行、活性污泥性质以及膜污染的影响.结果表明,ZnO纳米颗粒不利于微生物对有机物的去除,但是不会影响微生物对氨氮的去除.由于微滤膜的截留作用,ZnO纳米颗粒对MBR的出水没有影响.ZnO纳米颗粒的投加导致溶解性微生物产物(SMP)浓度从17.9mg/gVSS上升到35.0mg/gVSS左右,污泥粒径由162.9μm下降到105.2μm,引起了外部阻力的上升,造成了膜污染的加剧.ZnO纳米颗粒会抑制微生物活性和改变活性污泥中微生物的种群结构,这主要与ZnO纳米颗粒释放的Zn2+有关.