scholarly journals Green Graphene–Chitosan Sorbent Materials for Mercury Water Remediation

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1474 ◽  
Author(s):  
Ana Bessa ◽  
Gil Gonçalves ◽  
Bruno Henriques ◽  
Eddy M. Domingues ◽  
Eduarda Pereira ◽  
...  
Keyword(s):  
Self Assembly ◽  
Contact Time ◽  
Natural Waters ◽  
Synergistic Effects ◽  
Tap Water ◽  
Water Remediation ◽  
Ultrapure Water ◽  
Toxic Heavy Metals ◽  
Chloro Complexes ◽  
Sorbent Materials

The development of new graphene-based nanocomposites able to provide synergistic effects for the adsorption of toxic heavy metals in realistic conditions (environment) is of higher demand for future applications. This work explores the preparation of a green nanocomposite based on the self-assembly of graphene oxide (GO) with chitosan (CH) for the remediation of Hg(II) in different water matrices, including ultrapure and natural waters (tap water, river water, and seawater). Starting at a concentration of 50 μg L–1, the results showed that GO–CH nanocomposite has an excellent adsorption capacity of Hg (II) using very small doses (10 mg L–1) in ultrapure water with a removal percentage (% R) of 97 % R after only two hours of contact time. In the case of tap water, the % R was 81.4% after four hours of contact time. In the case of river and seawater, the GO–CH nanocomposite showed a limited performance due the high complexity of the water matrices, leading to a residual removal of Hg(II). The obtained removal of Hg(II) at equilibrium in river and seawater for GO–CH was 13% R and 7% R, respectively. Our studies conducted with different mimicked sea waters revealed that the removal of mercury is not affected by the presence of NO3– and Na+ (>90% R of Hg(II)); however, in the presence of Cl–, the mercury removal was virtually nonexistent (1% R of Hg(II)), most likely because of the formation of very stable chloro-complexes of Hg(II) with less affinity towards GO–CH.

Constructing multifunctional MOF@rGO hydro-/aerogels by the self-assembly process for customized water remediation

2017 ◽  
Vol 5 (23) ◽  
pp. 11873-11881 ◽  
Author(s):  
Jiajun Mao ◽  
Mingzheng Ge ◽  
Jianying Huang ◽  
Yuekun Lai ◽  
Changjian Lin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Synergistic Effects ◽  
Chemical Reduction ◽  
The Self ◽  
Water Remediation ◽  
Cross Linking ◽  
General Strategy ◽  
Assembly Process ◽  
One Step ◽  
First Time

We first time report a general strategy for one-step fabrication of a ZIF-8 MOF/RGO hydrogel, with the synergistic effects of chemical reduction and cross-linking by metal ions.

UV ability to inactivate microorganisms combined with factors affecting radiation

1997 ◽  
Vol 35 (11-12) ◽  
pp. 107-112 ◽  
Author(s):  
A. M. Shaban ◽  
G. E. El-Taweel ◽  
G. H. Ali
Keyword(s):  
Microbial Communities ◽  
Uv Radiation ◽  
Contact Time ◽  
Tap Water ◽  
Scenedesmus Obliquus ◽  
Morphological Characters ◽  
The Other ◽  
Bacterial Cells ◽  
Dark Repair ◽  
Nile Water

In the present study, the effect of UV radiation on the inactivation of a range of microorganisms was studied. Each organism was seeded into sterile tap water and exposed to UV in batch experiments with changing turbidities. In addition, the effect of UV on microbial communities in river Nile water was examined. It was found that 1min contact time (0.5L/min flow rate) was effective against vegetative cells levels almost reaching zero (except with Staphylococcus aureus). On the other hand, spore-forming bacteria, Candida albicans and coliphage were more resistant to UV. This contact time caused coenobia cells in single form with Scenedesmus obliquus while for Microcystis aeruginosa colonies broke into smaller groups. Exposure of Nile water microbial communities to UV showed that yeasts and Aeromonas survived better than the other organisms while in the phytoplankton partial fragmentation occurred in some algal groups. The protective effect of turbidity differed between organisms, with increased contact time under conditions of stable turbidity having no effect on the organisms. At 20 NTU the UV radiation had no effect on the morphological characters of algal cells. In reactivation experiments, it is clear that photoreactivation, and not dark repair, takes place with bacterial cells. Only coliphage had no photoreactivation and dark repair responses although with coliphage and host, both reactivation processes worked well. Moreover, the irradiated algae regained their normal shape after 3 days in suitable media and enough light.

scholarly journals Photocatalytic Degradation of Sulfolane Using a LED-Based Photocatalytic Treatment System

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 624
Author(s):  
Sripriya Dharwadkar ◽  
Linlong Yu ◽  
Gopal Achari
Keyword(s):  
Photocatalytic Degradation ◽  
Oil And Gas ◽  
Light Emitting Diode ◽  
Tap Water ◽  
Aqueous Media ◽  
Ultrapure Water ◽  
Light Emitting ◽  
Degradation Rates ◽  
Reduced Graphene ◽  
The Impact

Sulfolane is an emerging industrial pollutant detected in the environments near many oil and gas plants in North America. So far, numerous advanced oxidation processes have been investigated to treat sulfolane in aqueous media. However, there is only a few papers that discuss the degradation of sulfolane using photocatalysis. In this study, photocatalytic degradation of sulfolane using titanium dioxide (TiO2) and reduced graphene oxide TiO2 composite (RGO-TiO2) in a light-emitting diode (LED) photoreactor was investigated. The impact of different waters (ultrapure water, tap water, and groundwater) and type of irradiation (UVA-LED and mercury lamp) on photocatalytic degradation of sulfolane were also studied. In addition, a reusability test was conducted for the photocatalyst to examine the degradation of sulfolane in three consecutive cycles with new batches of sulfolane-contaminated water. The results show that LED-based photocatalysis was effective in degrading sulfolane in waters even after three photocatalytic cycles. UVA-LEDs displayed more efficient use of photon energy when compared with the mercury lamps as they have a narrow emission spectrum coinciding with the absorption of TiO2. The combination of UVA-LED and TiO2 yielded better performance than UVA-LED and RGO-TiO2 for the degradation of sulfolane. Much lower sulfolane degradation rates were observed in tap water and groundwater than ultrapure water.

scholarly journals Application of Anaerobic and Ozonation Processes in the Landfill Leachate Treatment

2006 ◽  
Vol 1 (3) ◽  
Author(s):  
A. Vilar ◽  
S. Gil ◽  
M. A. Aparicio ◽  
C. Kennes ◽  
M. C. Veiga
Keyword(s):  
Organic Matter ◽  
Landfill Leachate ◽  
Biological System ◽  
Contact Time ◽  
Treatment Process ◽  
Tap Water ◽  
Leachate Treatment ◽  
Ozone Dose ◽  
Pre Treatment ◽  
Ozonation Process

The optimization of leachate treatment was investigated as well as the configuration of a biological-ozonation process. The leachate used for the experiments was diluted to 1/5 with tap water and treated anaerobically. The anaerobic effluent and the raw leachate were treated with ozone in order to increase their biodegradability getting the minimum organic matter removal. Both were submitted to the ozonation process, applying a constant ozone dose and varying the contact time. The ozonation of raw leachate produced a decrease of COD and BOD5 concentrations as well as BOD5/COD ratios, applying an ozone dose of 38.72 mg/L·min and contact times between 15 and 60 minutes. Ozonation as a pre-treatment process to the biological system did not improve the biodegradability of the raw leachate. The anaerobic effluent from the reactor fed with leachate diluted to 1/5, was subjected to an ozone dose of 34.99 mg/L·min and applying different contact times. BODf values increased from 74.75 up to 1220 mg/L and BODf/COD ratios reached values higher than 1. Then, the application of ozone to the anaerobic effluent led to the improvement of the biodegradability of the leachate as well as the BODf/COD ratio for all the contact times used.

scholarly journals Screening Different Divalent and Trivalent Metals Containing Binary and Ternary Layered Double Hydroxides for Optimum Phosphate Uptake

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sattam Fahad Almojil ◽  
Mohamed Abdelhalim Othman
Keyword(s):  
Layered Double Hydroxides ◽  
Phosphate Uptake ◽  
Synergistic Effects ◽  
Bet Surface Area ◽  
Primary Role ◽  
Specific Element ◽  
Phosphate Ion ◽  
Sorbent Materials ◽  
Double Hydroxides

Abstract The elements constituting a layered double hydroxides material provide many alternatives for its optimization. Ten different layered double hydroxides materials with various combinations of Ni, Cu, Zn, Al, Cr, and Fe elements were studied as sorbent materials for phosphate ion. The type of element used in the layered double hydroxides affected the uptake capacity of phosphate. The influence of a specific element alone was not the primary role of enhancing the sorption performance of phosphate ion on the LDHs material. However, using specific two or three elements together is the key to achieve the best result due to synergistic effects. BET surface area of the sorbent showed no correlation with phosphate uptake. From the examined materials, Four layered double hydroxides of Cu-Zn-Cr, Zn-Cr, Ni-Al, and Cu-Ni-Cr showed high phosphate sorption capability. Sorption equilibrium isotherm, reaction kinetics, and desorption of phosphate from the sorbent materials were also investigated.

scholarly journals Self-assembly of mono- and poly-dispersed nanoparticles on emulsion droplets: antagonistic vs. synergistic effects as a function of particle size

2020 ◽  
Vol 22 (39) ◽  
pp. 22662-22673
Author(s):  
Abeer Khedr ◽  
Alberto Striolo
Keyword(s):  
Particle Size ◽  
Self Assembly ◽  
Synergistic Effects ◽  
Dissipative Particle Dynamics ◽  
Particle Dynamics ◽  
The Self ◽  
Oil Droplet ◽  
Emulsion Droplets ◽  
Dynamics Simulations

In this work, using dissipative particle dynamics simulations, we provide fundamental insights into the self-assembly of nanoparticles (NPs) on oil droplet surfaces.

Facile synthesis of novel Roe-like TiO2 hollow nanospheres with mesoporous cavity for improved photocatalytic activity

2017 ◽  
Vol 10 (03) ◽  
pp. 1750028 ◽  
Author(s):  
Yan Zhu ◽  
Xiaoxia Yan ◽  
Yuanxin Ge ◽  
Shumin Wang ◽  
Dongmei Deng ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Self Assembly ◽  
Charge Separation ◽  
Synergistic Effects ◽  
Assembly Process ◽  
Hollow Nanospheres ◽  
Facile Synthesis

A facile approach was developed to synthesize novel Roe-like TiO2 hollow nanospheres via a template-assisted self-assembly process. These TiO2 nanospheres possessing mesoporous cavity manifest significantly improved photocatalytic activity owing to the synergistic effects of increased charge separation, more efficient use of the light and specific surface area.

scholarly journals Environmental Assessment of Humic Acid Coated Magnetic Materials Used as Catalyst in Photo-Fenton Processes

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 771
Author(s):  
Mattia Costamagna ◽  
Nuno P. F. Gonçalves ◽  
Alessandra Bianco Prevot
Keyword(s):  
Humic Acid ◽  
Environmental Sustainability ◽  
Natural Waters ◽  
Water Remediation ◽  
Strongly Correlated ◽  
Fenton Catalyst ◽  
Treatment Technologies ◽  
Magnetite Particles ◽  
Chemical Inputs ◽  
Materials Used

Persistent organic pollutants have been increasingly detected in natural waters, and this represents a real challenge to the quality of this resource. To remove these species, advanced treatment technologies are required. Among these technologies, Fenton-like and photo-Fenton-like processes have been investigated for the removal of pollutants from water. Delicate aspects of photo-Fenton processes are that light-driven processes are energy intensive and require a fair amount of chemical inputs, which strongly affects their overall environmental burdens. At present, aside from determining the efficiency of the processes to remove pollutants of a particular technology, it becomes fundamental to assess also the environmental sustainability of the overall process. In this work, the methodology of the life cycle assessment (LCA) was applied to identify the hotspots of using magnetite particles covered with humic acid (Fe3O4/HA) as a heterogeneous photo-Fenton catalyst for water remediation. The sustainability of the overall process was considered, and a comparative LCA study was performed between H2O2 and persulfate activation at different pH. The addition of humic substances to the particles allows the effectiveness of the catalyst to improve without increasing the environmental impacts; these processes are strongly correlated with energy consumption and therefore with the efficiency of the process. For this reason, working at acidic pH allows us to contain the impacts.

Purification of Contaminated Water with Chromium (VI) Using Pseudomonas aeruginosa

2016 ◽  
Vol 721 ◽  
pp. 143-148 ◽  
Author(s):  
Nora Noureddine ◽  
Samia Benhammadi ◽  
Fouad Kara ◽  
Hakim Aguedal ◽  
Abdelkader Iddou ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Hexavalent Chromium ◽  
Contact Time ◽  
Culture Broth ◽  
Contaminated Water ◽  
Toxic Heavy Metals ◽  
Initial Concentration ◽  
Chromium Vi ◽  
Batch System ◽  
Uncontaminated Soil

A bacterial strain Pseudomonas aeruginosa isolated from an uncontaminated soil has been used for the removal of hexavalent chromium (Cr (VI)). The experiments were carried out in batch system in a culture broth. The results obtained have shown that 100% of Cr (VI) are removed. Contact time, initial concentration of the hexavalent chromium, temperature, as well as the nature of the culture broth have influenced this elimination. To the initial concentration of 20g/L of Cr (VI) the elimination rates are lower, while the reverse occurs for an initial concentration of 8g/L. This study allows considering the use of Pseudomonas aeruginosa in the treatment of water polluted by toxic heavy metals such as Cr (VI).

scholarly journals Disinfection efficacy of chlorine and peracetic acid alone or in combination against Aspergillus spp. and Candida albicans in drinking water

2011 ◽  
Vol 10 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Maurizio Sisti ◽  
Giorgio Brandi ◽  
Mauro De Santi ◽  
Laura Rinaldi ◽  
Giuditta F. Schiavano
Keyword(s):  
Drinking Water ◽  
Candida Albicans ◽  
Peracetic Acid ◽  
Contact Time ◽  
Distribution Systems ◽  
Water Distribution ◽  
Synergistic Effects ◽  
Water Disinfection ◽  
Experimental Conditions ◽  
Complete Inactivation

The aim of the present study was to evaluate the fungicidal activity of chlorine and peracetic acid in drinking water against various pathogenic Aspergillus spp. and Candida albicans strains. A. nidulans exhibited the greatest resistance, requiring 10 ppm of chlorine for 30 min contact time for a complete inactivation. Under the same experimental conditions, peracetic acid was even less fungicidal. In this case, A. niger proved to be the most resistant species (50 ppm for 60 min for complete inactivation). All Aspergillus spp. were insensitive to 10 ppm even with extended exposure (>5 h). The combination of chlorine and peracetic acid against Aspergillus spp. did not show synergistic effects except in the case of A. flavus. Complete growth inhibition of C. albicans was observed after about 3 h contact time with 0.2 ppm. C. albicans was less sensitive to peracetic acid. Hence the concentrations of chlorine that are usually present in drinking water distribution systems are ineffective against several Aspergillus spp. and peracetic acid cannot be considered an alternative to chlorine for disinfecting drinking water. The combination of the two biocides is not very effective in eliminating filamentous fungi at the concentrations permitted for drinking water disinfection.

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