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El-Kalliny AS, Abdel-Wahed MS, El-Zahhar AA, Hamza IA, Gad-Allah TA. Nanomaterials: a review of emerging contaminants with potential health or environmental impact. DISCOVER NANO 2023; 18:68. [PMID: 37382722 PMCID: PMC10409958 DOI: 10.1186/s11671-023-03787-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 02/02/2023] [Indexed: 06/30/2023]
Abstract
Nanotechnologies have been advantageous in many sectors and gaining much concern due to the unique physical, chemical and biological properties of nanomaterials (NMs). We have surveyed peer-reviewed publications related to "nanotechnology", "NMs", "NMs water treatment", "NMs air treatment", and "NMs environmental risk" in the last 23 years. We found that most of the research work is focused on developing novel applications for NMs and new products with peculiar features. In contrast, there are relatively few of publications concerning NMs as environmental contaminants relative to that for NMs applications. Thus, we devoted this review for NMs as emerging environmental contaminants. The definition and classification of NMs will be presented first to demonstrate the importance of unifying the NMs definition. The information provided here should facilitate the detection, control, and regulation of NMs contaminants in the environment. The high surface-area-to-volume ratio and the reactivity of NMs contaminants cause the prediction of the chemical properties and potential toxicities of NPs to be extremely difficult; therefore, we found that there are marked knowledge gaps in the fate, impact, toxicity, and risk of NMs. Consequently, developing and modifying extraction methods, detection tools, and characterization technologies are essential for complete risk assessment of NMs contaminants in the environment. This will help also in setting regulations and standards for releasing and handling NMs as there are no specific regulations. Finally, the integrated treatment technologies are necessary for the removal of NMs contaminants in water. Also, membrane technology is recommended for NMs remediation in air.
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Affiliation(s)
- Amer S El-Kalliny
- Water Pollution Research Department, National Research Centre, 33 El Buhouth St., Dokki, Giza, 12622, Egypt
| | - Mahmoud S Abdel-Wahed
- Water Pollution Research Department, National Research Centre, 33 El Buhouth St., Dokki, Giza, 12622, Egypt.
| | - Adel A El-Zahhar
- Department of Chemistry, College of Science, King Khalid University, P.O. Box 9004, Abha, 61413, Saudi Arabia
| | - Ibrahim A Hamza
- Water Pollution Research Department, National Research Centre, 33 El Buhouth St., Dokki, Giza, 12622, Egypt
| | - Tarek A Gad-Allah
- Water Pollution Research Department, National Research Centre, 33 El Buhouth St., Dokki, Giza, 12622, Egypt
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Crintea A, Carpa R, Mitre AO, Petho RI, Chelaru VF, Nădășan SM, Neamti L, Dutu AG. Nanotechnology Involved in Treating Urinary Tract Infections: An Overview. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:555. [PMID: 36770516 PMCID: PMC9919202 DOI: 10.3390/nano13030555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/22/2023] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Considered as the most frequent contaminations that do not require hospitalization, urinary tract infections (UTIs) are largely known to cause significant personal burdens on patients. Although UTIs overall are highly preventable health issues, the recourse to antibiotics as drug treatments for these infections is a worryingly spread approach that should be addressed and gradually overcome in a contemporary, modernized healthcare system. With a virtually alarming global rise of antibiotic resistance overall, nanotechnologies may prove to be the much-needed 'lifebuoy' that will eventually suppress this prejudicial phenomenon. This review aims to present the most promising, currently known nano-solutions, with glimpses on clinical and epidemiological aspects of the UTIs, prospective diagnostic instruments, and non-antibiotic treatments, all of these engulfed in a comprehensive overview.
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Affiliation(s)
- Andreea Crintea
- Department of Medical Biochemistry, Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Rahela Carpa
- Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
| | - Andrei-Otto Mitre
- Department of Pathophysiology, Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Robert Istvan Petho
- Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Vlad-Florin Chelaru
- Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Sebastian-Mihail Nădășan
- Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Lidia Neamti
- Department of Medical Biochemistry, Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Alina Gabriela Dutu
- Department of Medical Biochemistry, Faculty of Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
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Analysis of Seasonal Variations in Surface Water Quality over Wet and Dry Regions. WATER 2022. [DOI: 10.3390/w14071058] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Water quality is highly affected by riverside vegetation in different regions. To comprehend this research, the study area was parted into wet and dry regions. The WASP8 was applied for the simulations of water quality profile over both Waterways selected from each region. It was found that the Ara Waterway, located in the wet regions, has a higher water quality variation in seasonal scale than that of the Yamuna Waterway, which is in the dry region. The interrelationship between river water quality variables and NDVI produce higher association for water quality variables with Pearson correlation coefficient values of about 0.66, 0.68 and −0.58, respectively, over the annual and seasonal scales in the energy limited regions. This approach will help in monitoring the seasonal variation and effect of the vegetation biomass on water quality for the sustainable water environment.
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Comparative effects of zinc oxide nanoparticles over the interfacial properties of low concentrations of ionic surfactants at interfaces. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.128241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Zhang B, Tang X, Fan C, Hao W, Zhao Y, Zeng Y. Cationic polyacrylamide alleviated the inhibitory impact of ZnO nanoparticles on anaerobic digestion of waste activated sludge through reducing reactive oxygen species induced. WATER RESEARCH 2021; 205:117651. [PMID: 34560617 DOI: 10.1016/j.watres.2021.117651] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 08/19/2021] [Accepted: 09/05/2021] [Indexed: 06/13/2023]
Abstract
The enrichment of zinc oxide nanoparticles (ZnO NPs) in waste activated sludge (WAS) has raised concerns about their potential impact on anaerobic digestion of WAS. To date, there is no information regarding how to attenuate the negative effects of ZnO NPs on WAS anaerobic digestion. In this study, it was found that the appropriate amount of cationic polyacrylamide (cPAM) could mitigate the toxicity of ZnO NPs. During short-term exposure, the supplement of 4.0 mg cPAM/g TSS significantly restored biochemical methane potential from 28.6% inhibition to 9.3% inhibition compared with the control digester (P < 0.01). The spiked cPAM promoted the solubilization and acidification stages by weakening the contact between ZnO NPs and anaerobes in anaerobic digestion process, thus providing abundant substance for sequent bio-utilization. In the long-term semi-continues operated reactor, the continuous replacement of cPAM (at 4.0 mg/g TSS) significantly strengthened the recovery of VS destruction rate (20.3% to 26.4%, P < 0.01) and the daily yield of methane (93.5 mL/d to 124.2 mL/d, P < 0.01). Consistent with the restored performance, the application of cPAM increased the total microbial communities and the relative abundances of dominant acidogens and methanogens. Further explorations showed decreased toxicity of ZnO NPs primarily attributed to the decline of reactive oxygen species (ROS) induced by ZnO NPs.
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Affiliation(s)
- Baowei Zhang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Xiang Tang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Changzheng Fan
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China.
| | - Wanle Hao
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Yilin Zhao
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Yanjing Zeng
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
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Sajednia G, Rahimi E, Alvand N, Karbassi A, Baghdadi M. Fibrous adsorbent derived from sulfonation of cotton waste: application for removal of cadmium sulfide nanoparticles from aquatic media. SN APPLIED SCIENCES 2019. [DOI: 10.1007/s42452-019-1525-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Xu L, Yang X, Ding H, Li S, Li M, Wang D, Xia J. Synthesis of green fluorescent carbon materials using byproducts of the sulfite-pulping procedure residue for live cell imaging and Ag + ion determination. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 102:917-922. [PMID: 31147063 DOI: 10.1016/j.msec.2019.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 04/04/2019] [Accepted: 04/06/2019] [Indexed: 10/27/2022]
Abstract
A simple synthesis strategy was designed and applied to synthesize nitrogen and sulfur co-doped aminated ligninsulfonate/graphene quantum dots (ASL/GQDs) composites using citric acid monohydrate and byproducts of the sulfite-pulping procedure (sodium lignosulfonate). The combination of these two materials improves surface chemical activities and electronic characteristics. As a result,the combination offers excellent photoluminescence properties and sensitivity. The fluorescence intensity of the as-prepared ASL/GQDs composites is more than three times that of the free GQDs. ASL/GQDs based fluorescent probe was applied to sensitively determine Ag+ with a good linearity in a range from 0.005 to 500 μM with a correlation coefficient of 0.99. The method was also used successfully to determine the amount of Ag+ in environmental water samples. Using an MTT assay, the ASL/GQDs have low toxicity and are biocompatible with A549 cells, and may be successfully used to image A549 cells.
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Affiliation(s)
- Lina Xu
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China.
| | - Xiaohua Yang
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China
| | - Haiyang Ding
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China
| | - Shouhai Li
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China
| | - Mei Li
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China
| | - Dan Wang
- College of Chemistry and Materials Science, Guangxi Teachers Education University, Nanning 530001, China
| | - Jianling Xia
- Institute of Chemical Industry of Forestry Products, CAF, Key Lab. of Biomass Energy and Material, Jiangsu Province, National Engineering Lab. for Biomass Chemical Utilization, Key and Lab. on Forest Chemical Engineering, SFA, Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China.
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Khan R, Inam MA, Khan S, Jiménez AN, Park DR, Yeom IT. The Influence of Ionic and Nonionic Surfactants on the Colloidal Stability and Removal of CuO Nanoparticles from Water by Chemical Coagulation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16071260. [PMID: 30970550 PMCID: PMC6479800 DOI: 10.3390/ijerph16071260] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/06/2019] [Accepted: 04/07/2019] [Indexed: 11/17/2022]
Abstract
The widespread use of copper oxide nanoparticles (CuO NPs) and surfactants in various consumer products makes it likely that they coexist in aqueous environments, making it important to study the effects of surfactants on the fate and transport behavior of CuO NPs. The present study aims to investigate the influence of anionic sodium lauryl sulfate (SLS) and nonionic nonylphenol ethoxylate (NPEO, Tergitol NP-9), on CuO NPs adsorption, aggregation, and removal from water by the coagulation process. The result of the sorption study indicates that both surfactants could be adsorbed on the surface of CuO NPs, and that SLS remarkably decreases the ζ potential as well as the hydrodynamic diameter (HDD) of CuO as compared to NP-9. The kinetic aggregation study showed that both SLS and NP-9 reduced the HDD of CuO NPs and retarded the settling rates at surfactant concentrations above 0.015% (w:v) over a 24 h-period. Moreover, enhanced aggregation of CuO NPs was observed in two environmental waters as compared to pure water, which could be related to their high ionic strength. The addition of surfactants in natural waters has been shown to reduce the aggregation and sedimentation of CuO; however, the reductive effect of SLS was more pronounced than that of NP-9. Finally, the coagulation results showed that the removal efficiencies of CuO, Cu2+, and the surfactant in all tested waters at optimum ferric chloride dosage reached around 98, 95, and 85%, respectively. Furthermore, the coagulation mechanism revealed that the combination of charge neutralization and adsorptive micellar flocculation (AMF) might be involved in the removal of both pollutants. The results of the present study provide new insight into the environmental behavior of coexisting NPs and surfactants in wastewater treatment processes.
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Affiliation(s)
- Rizwan Khan
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Muhammad Ali Inam
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Sarfaraz Khan
- Key Laboratory of the Three Gorges Reservoir Region Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - Andrea Navarro Jiménez
- Key Laboratory of the Three Gorges Reservoir Region Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - Du Ri Park
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Ick Tae Yeom
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
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Inam MA, Khan R, Park DR, Khan S, Uddin A, Yeom IT. Complexation of Antimony with Natural Organic Matter: Performance Evaluation during Coagulation-Flocculation Process. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16071092. [PMID: 30934698 PMCID: PMC6480550 DOI: 10.3390/ijerph16071092] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/25/2019] [Accepted: 03/25/2019] [Indexed: 11/30/2022]
Abstract
The presence of natural organic matter (NOM) in drinking water sources can stabilize toxic antimony (Sb) species, thus enhancing their mobility and causing adverse effects on human health. Therefore, the present study aims to quantitatively explore the complexation of hydrophobic/hydrophilic NOM, i.e., humic acid (HA), salicylic acid (SA), and L-cysteine (L-cys), with Sb in water. In addition, the removal of Sb(III, V) species and total organic carbon (TOC) was evaluated with ferric chloride (FC) as a coagulant. The results showed a stronger binding affinity of hydrophobic HA as compared to hydrophilic NOM. The optimum FC dose required for Sb(V) removal was found to be higher than that for Sb(III), due to the higher complexation ability of hydrophobic NOM with antimonate than antimonite. TOC removal was found to be higher in hydrophobic ligands than hydrophilic ligands. The high concentration of hydrophobic molecules significantly suppresses the Sb adsorption onto Fe precipitates. An isotherm study suggested a stronger adsorption capacity for the hydrophobic ligand than the hydrophilic ligand. The binding of Sb to NOM in the presence of active Fe sites was significantly reduced, likely due to the adsorption of contaminants onto precipitated Fe. The results of flocs characteristics revealed that mechanisms such as oxidation, complexation, charge neutralization, and adsorption may be involved in the removal of Sb species from water. This study may provide new insights into the complexation behavior of Sb in NOM-laden water as well as the optimization of the coagulant dose during the water treatment process.
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Affiliation(s)
- Muhammad Ali Inam
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Rizwan Khan
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Du Ri Park
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Sarfaraz Khan
- Key Laboratory of the Three Gorges Reservoir Region Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - Ahmed Uddin
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Sciences and Technology, Nanjing 210094, China.
| | - Ick Tae Yeom
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
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Interaction between Persistent Organic Pollutants and ZnO NPs in Synthetic and Natural Waters. NANOMATERIALS 2019; 9:nano9030472. [PMID: 30901850 PMCID: PMC6474098 DOI: 10.3390/nano9030472] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 12/23/2022]
Abstract
The use of zinc oxide nanoparticles (ZnO NPs) and polybrominated diphenyl ethers (PBDPEs) in different products and applications leads to the likelihood of their co-occurrence in the aquatic system, making it important to study the effect of PBDPEs on the fate and transport of ZnO NPs. In this study, we determine the influence of PBDPEs (BDPE-47 and BDPE-209) on the colloidal stability and physicochemical properties of ZnO NPs in different aqueous matrices. The results indicated the shift in ζ potential of ZnO NP from positive to negative in the presence of both PBDPEs in all tested waters; however, the effect on the NPs surface potential was specific to each water considered. The lower concentration of the PBDPEs (e.g., 0.5 mg/L) significantly reduced the ζ potential and hydrodynamic diameter (HDD) of ZnO NP, even in the presence of high content of dissolved organic matter (DOM) in both freshwater and industrial wastewater. Moreover, both BDPE-47 and BDPE-209 impede the agglomeration of ZnO NP in simple and natural media, even in the presence of monovalent and polyvalent cations. However, the effect of BDPE-47 on the ζ potential, HDD, and agglomeration of ZnO NP was more pronounced than that of BDPE-209 in all tested waters. The results of Fourier transform infrared (FT-IR) and X-ray Photon Spectroscopy (XPS) further confirm the adsorption of PBDPEs onto ZnO NP surface via aromatic ether groups and Br elements. The findings of this study will facilitate a better understanding of the interaction behavior between the ZnO NPs and PBDPEs, which can reduce the exposure risk of aquatic organisms to both pollutants.
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Khan R, Inam MA, Park DR, Khan S, Akram M, Yeom IT. The Removal of CuO Nanoparticles from Water by Conventional Treatment C/F/S: The Effect of pH and Natural Organic Matter. Molecules 2019; 24:molecules24050914. [PMID: 30841649 PMCID: PMC6429111 DOI: 10.3390/molecules24050914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 12/02/2022] Open
Abstract
The increased use of engineered nanoparticles (ENPs), such as copper oxide nanoparticles (CuO NPs), in commercial products and applications raises concern regarding their possible release into freshwater sources. Therefore, their removal from water is important to eliminate adverse environmental and human health effects. In this study, the effects of pH and natural organic matter (NOM), i.e., humic acid (HA) and salicylic acid (SA) on the removal of CuO NPs by coagulation/flocculation/sedimentation (C/F/S) were evaluated. The results indicated that pH significantly affects the coagulation efficiency, where 10–60% CuO NPs removal was achieved under extreme acidic/alkaline conditions. However, at neutral pH, removal of up to 90% was observed with a lower ferric chloride (FC) dosage (0.2 mM). The coagulation efficiency and mechanism were strongly affected by the type of Fe species present in the aqueous phase, which is mainly controlled by pH. Higher concentrations of both HA and SA decrease the CuO NPs agglomeration rate, and thereby improve the colloidal stability due to the NOM molecules adsorbed onto the NPs surface. The presence of hydrophobic HA needs a higher FC dosage of 0.5–0.8 mM than a dosage of hydrophilic SA of 0.25–0.35 mM, to obtain a similar CuO coagulation efficiency. Moreover, higher removals of dissolved organic carbon (DOC) and UV254 were observed more in hydrophobic NOM than in hydrophilic. The results of the Fourier transform infrared (FT-IR) analysis of FC composite flocs confirm that the charge neutralization and enmeshment of coagulant might be a possible removal mechanism. The findings of the current study may provide critical information in the prediction of the fate, mobility, and removal of CuO NPs during C/F/S in water treatment.
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Affiliation(s)
- Rizwan Khan
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Muhammad Ali Inam
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Du Ri Park
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Sarfaraz Khan
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
| | - Muhammad Akram
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266200, China.
| | - Ick Tae Yeom
- Graduate School of Water Resources, Sungkyunkwan University (SKKU) 2066, Suwon 16419, Korea.
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Firms’ Sustainability: Does Economic Policy Uncertainty Affect Internal Control? SUSTAINABILITY 2019. [DOI: 10.3390/su11030794] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper studies whether economic policy uncertainty (EPU) influences internal control (IC). Exploiting EPU as an exogenous shock and using unique internal control index data at the firm level from China, we can make causal inferences about the EPU effect on IC, and provide new insight into firms’ sustainability. Our results show that firms tend to cope with higher EPU by improving IC, indicating their efforts to ensure sustainability development. We also find that this trend is intensified for firms localized in regions with a lower marketization degree, state-owned firms, or firms with fewer analysts following. Further analyses show that EPU significantly reduces the internal control auditing fees, hence backing up the association between EPU and IC. Unlike the previous literature, this paper shows the important role of internal control for firms in coping with EPU, which is of crucial significance to how firms seek to adhere to sustainable development and how economic policy works best.
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