Polyelectrolyte-Enhanced Ultrafiltration (PEUF) Process for Low Level Arsenic Removal: Recovery of Polyelectrolyte from Retentate Stream

2012 ◽  
Vol 506 ◽  
pp. 27-30 ◽  
Author(s):  
P. Pookrod ◽  
W. Dungkaew ◽  
P. Un-Arn ◽  
K.J. Haller
Keyword(s):  
Arsenic Removal ◽  
Concentration Level ◽  
Divalent Cations ◽  
Cationic Polyelectrolyte ◽  
Molar Ratio ◽  
Contaminated Water ◽  
Process Technology ◽  
Low Level ◽  
Low Levels ◽  
Size And Morphology

Removal of low levels of arsenic from contaminated water using the polyelectrolyte-enhanced ultrafiltration or PEUF process technology has been studied. The cationic polyelectrolyte poly (diallyldimethyl ammonium chloride), PDADMAC, was utilized to bind arsenic (in the form of arsenate anion) in contaminated water and the polyelectrolyte-arsenate complex solution was then filtered off (as retentate) by ultrafiltration. The 99-99.9% arsenic removal from synthetic low level arsenic (100 ppb) contaminated water demonstrates that the technology can easily achieve the relatively new international arsenic maximum concentration level of 10 ppb. To make the PEUF process more economical and environmentally friendly, the PDADMAC in the retentate must be recovered. Precipitation of PDADMAC-arsenate solutions with divalent cations has been studied to separate out metal-arsenate compounds leaving free PDADMAC to reuse in the process. The metal-arsenate compound precipitation is strongly affected by divalent metal:As molar ratio, and pH of the solution. The precipitation results also suggest that polyelectrolyte retards formation of the metal-arsenate compounds and affects the size and morphology of the particles formed, thus directly affecting the sedimentation rate of the resulting precipitate.

Arsenic Removal by Precipitation with Calcium Phosphate Hydroxyapatite

2012 ◽  
Vol 506 ◽  
pp. 413-416 ◽  
Author(s):  
W. Dungkaew ◽  
K.J. Haller ◽  
A.E. Flood ◽  
J.F. Scamehorn
Keyword(s):  
Calcium Phosphate ◽  
Water Sample ◽  
Removal Efficiency ◽  
Arsenic Removal ◽  
Arsenic Speciation ◽  
Arsenic Concentration ◽  
Contaminated Water ◽  
Low Levels ◽  
Removal Of Arsenic ◽  
Key Parameter

The removal of arsenic from synthetic arsenic contaminated water sample by precipitating arsenic (in the form of arsenate oxyanion) with calcium phosphate hydroxyapatite, HAp, was studied under conditions that induce arsenate incorporated calcium phosphate hydroxyapatite, Ca (P/As)HAp, to form. Arsenate is able to substitute for a fraction of the phosphate in HAp host material as it forms. Consequently, arsenic is successfully removed from the contaminated water achieving up to 99% arsenic removal from 25 ppm initial arsenic concentration. The Ca:(P+As) and P:As mole ratios were found to play an important role in arsenic removal efficiency. Higher Ca:(P+As) and P:As mole ratios give higher arsenic removal efficiency. Surprisingly, the pH of the initial anion solution, a key parameter in arsenic speciation, was found to not have a significant effect on arsenic removal by this process. The advantage of this process is that the precipitation can occur rapidly at relatively low levels of arsenic contamination, implying an easy and inexpensive process for arsenic removal can be developed based on this approach.

Arsenic removal by MF membrane with chemical sludge adsorption and NF membrane equipped with vibratory shear enhanced process

2003 ◽  
Vol 3 (5-6) ◽  
pp. 303-310 ◽  
Author(s):  
S.-H. Yi ◽  
S. Ahmed ◽  
Y. Watanabe ◽  
K. Watari
Keyword(s):  
Arsenic Removal ◽  
Membrane Surface ◽  
Membrane Process ◽  
Low Concentrations ◽  
Strong Shear ◽  
Low Levels ◽  
Removal Processes ◽  
Removal Of Arsenic ◽  
Concentration Polarization Layer ◽  
Chemical Sludge

Conventional arsenic removal processes have difficulty removing low concentrations of arsenic ion from water. Therefore, it is very hard to comply with stringent low levels of arsenic, such as below 10 μg/L. So, we have developed two arsenic removal processes which are able to comply with more stringent arsenic regulations. They are the MF membrane process combined with chemical sludge adsorption and NF membrane process equipped with the vibratory shear enhanced process (VSEP). In this paper, we examine the performance of these new processes for the removal of arsenic ion of a low concentration from water. We found that chemical sludge produced in the conventional rapid sand filtration plants can effectively remove As (V) ions of H2AsO4- and HAsO42- through anion exchange reaction. The removal efficiency of MF membrane process combined with chemical sludge adsorption increased to about 36%, compared to MF membrane alone. The strong shear force on the NF membrane surface produced by vibration on the VSEP causes the concentration polarization layer to thin through increased back transport velocity of particles. So, it can remove even dissolved constituents effectively. Therefore, As (V) ions such as H2AsO4- and HAsO42- can be removed. The concentration of As (V) ions decreased from 50 μg/L to below 10 μg/L and condensation factor in recirculating water increased up to 7 times by using NF membrane equipped with VSEP.

scholarly journals Nitrate-dominated PM<sub>2.5</sub> and elevation of particle pH observed in urban Beijing during the winter of 2017

2020 ◽  
Vol 20 (8) ◽  
pp. 5019-5033 ◽  
Author(s):  
Yuning Xie ◽  
Gehui Wang ◽  
Xinpei Wang ◽  
Jianmin Chen ◽  
Yubao Chen ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Ammonia Concentration ◽  
Historical Record ◽  
Molar Ratio ◽  
Effective Control ◽  
Nitrate Content ◽  
Chinese Government ◽  
Low Level ◽  
The Impact ◽  
Pollution Episodes

Abstract. The Chinese government has exerted strict emission controls to mitigate air pollution since 2013, which has resulted in significant decreases in the concentrations of air pollutants such as SO2. Strict pollution control actions also reduced the average PM2.5 concentration to the low level of 39.7 µg m−3 in urban Beijing during the winter of 2017. To investigate the impact of such changes on the physiochemical properties of atmospheric aerosols in China, we conducted a comprehensive observation focusing on PM2.5 in Beijing during the winter of 2017. Compared with the historical record (2014–2017), SO2 decreased to the low level of 3.2 ppbv in the winter of 2017, but the NO2 level was still high (21.4 ppbv in the winter of 2017). Accordingly, the contribution of nitrate (23.0 µg m−3) to PM2.5 far exceeded that of sulfate (13.1 µg m−3) during the pollution episodes, resulting in a significant increase in the nitrate-to-sulfate molar ratio. The thermodynamic model (ISORROPIA II) calculation results showed that during the PM2.5 pollution episodes particle pH increased from 4.4 (moderate acidic) to 5.4 (more neutralized) when the molar ratio of nitrate to sulfate increased from 1 to 5, indicating that aerosols were more neutralized as the nitrate content elevated. Controlled variable tests showed that the pH elevation should be attributed to nitrate fraction increase other than crustal ion and ammonia concentration increases. Based on the results of sensitivity tests, future prediction for the particle acidity change was discussed. We found that nitrate-rich particles in Beijing at low and moderate humid conditions (RH: 20 %–50 %) can absorb twice the amount of water that sulfate-rich particles can, and the nitrate and ammonia with higher levels have synergetic effects, rapidly elevating particle pH to merely neutral (above 5.6). As moderate haze events might occur more frequently under abundant ammonia and nitrate-dominated PM2.5 conditions, the major chemical processes during haze events and the control target should be re-evaluated to obtain the most effective control strategy.

Arsenic removal from contaminated water by ultrafine δ-FeOOH adsorbents

2014 ◽  
Vol 237 ◽  
pp. 47-54 ◽  
Author(s):  
Márcia C.S. Faria ◽  
Renedy S. Rosemberg ◽  
Cleide A. Bomfeti ◽  
Douglas S. Monteiro ◽  
Fernando Barbosa ◽  
...  
Keyword(s):  
Arsenic Removal ◽  
Contaminated Water

scholarly journals Do overweight/obesity and low levels of leisure-time vigorous physical activity moderate the effect of occupational physical activity on self-rated health of construction workers?

2021 ◽  
Author(s):  
M. Van den Berge ◽  
S. H. Van Oostrom ◽  
H. F. Van der Molen ◽  
S. J. W. Robroek ◽  
C. T. J. Hulshof ◽  
...  
Keyword(s):  
Physical Activity ◽  
Material Handling ◽  
Vigorous Physical Activity ◽  
Construction Workers ◽  
Low Level ◽  
Self Rated Health ◽  
Manual Material Handling ◽  
Strenuous Work ◽  
Low Levels

Abstract Purpose To investigate the combined effects of occupational physical activity (OPA) and either overweight/obesity or low levels of leisure-time vigorous physical activity (LTVPA) on self-rated health. Methods A longitudinal study was performed among 29,987 construction workers with complete data on 2 Workers’ Health Surveillance Programs during 2010–2018. Self-reported OPA involved strenuous work postures and manual material handling. Low level of LTVPA was defined as self-reported vigorous activity for less than three times per week lasting at least 20 min per session. Overweight and obesity were based on Body Mass Index (BMI) (25.0 ≤ BMI < 30.0 kg/m2 and BMI ≥ 30.0 kg/m2, respectively) using measured body height and weight. Self-rated health was measured using a single item question. Logistic regression analysis was used to investigate the associations between the separate risk factors at baseline and self-rated health at follow-up. The combined effects of demanding OPA and either overweight/obesity or low level of LTVPA on self-rated health were analyzed using the relative excess risk due to interaction (RERI). Results Mean follow-up duration was 31.7 (SD = 14.9) months. Construction workers with strenuous work postures (OR 1.35 95% CI 1.25–1.46), manual material handling (OR 1.29 95% CI 1.19–1.40), obesity (OR 1.31 95% CI 1.17–1.47) and low LTVPA (OR 1.13 95% CI 1.01–1.25) were more likely to report poor self-rated health at follow-up. No statistically significant interaction effects were found for OPA and obesity or low LTVPA. Conclusions OPA, obesity and low level of LTVPA were separate risk factors for poor self-rated health, but did not appear to have a synergistic effect.

scholarly journals Cytotoxic Effect of Progesterone, Tamoxifen and Their Combination in Experimental Cell Models of Human Adrenocortical Cancer

2021 ◽  
Vol 12 ◽  
Author(s):  
Elisa Rossini ◽  
Mariangela Tamburello ◽  
Andrea Abate ◽  
Silvia Beretta ◽  
Martina Fragni ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Cytotoxic Effect ◽  
Clinical Approach ◽  
Cell Models ◽  
Adrenocortical Cancer ◽  
Experimental Cell ◽  
Low Level ◽  
H295r Cells ◽  
Low Levels ◽  
Protein Reduction

Progesterone (Pg) and estrogen (E) receptors (PgRs and ERs) are expressed in normal and neoplastic adrenal cortex, but their role is not fully understood. In literature, Pg demonstrated cytotoxic activity on AdrenoCortical Carcinoma (ACC) cells, while tamoxifen is cytotoxic in NCI-H295R cells. Here, we demonstrated that in ACC cell models, ERs were expressed in NCI-H295R cells with a prevalence of ER-β over the ER-α.Metastasis-derived MUC-1 and ACC115m cells displayed a very weak ER-α/β signal, while PgR cells were expressed, although at low level. Accordingly, these latter were resistant to the SERM tamoxifen and scarcely sensitive to Pg, as we observed a lower potency compared to NCI-H295R cells in cytotoxicity (IC50: MUC-1 cells: 67.58 µM (95%CI: 63.22–73.04), ACC115m cells: 51.76 µM (95%CI: 46.45–57.67) and cell proliferation rate. Exposure of NCI-H295R cells to tamoxifen induced cytotoxicity (IC50: 5.43 µM (95%CI: 5.18–5.69 µM) mainly involving ER-β, as their nuclear localization increased after tamoxifen: Δ A.U. treated vs untreated: 12 h: +27.04% (p &lt; 0.01); 24 h: +36.46% (p &lt; 0.0001). This effect involved the SF-1 protein reduction: Pg: −36.34 ± 9.26%; tamoxifen: −46.25 ± 15.68% (p &lt; 0.01). Finally, in a cohort of 36 ACC samples, immunohistochemistry showed undetectable/low level of ERs, while PgR demonstrated a higher expression. In conclusion, ACC experimental cell models expressed PgR and low levels of ER in line with data obtained in patient tissues, thus limiting the possibility of a clinical approach targeting ER. Interestingly, Pg exerted cytotoxicity also in metastatic ACC cells, although with low potency.

scholarly journals Evaluation of Distributed Collaborative Adaptive Sensing for Detection of Low-Level Circulations and Implications for Severe Weather Warning Operations

2010 ◽  
Vol 25 (1) ◽  
pp. 173-189 ◽  
Author(s):  
J. Brotzge ◽  
K. Hondl ◽  
B. Philips ◽  
L. Lemon ◽  
E. J. Bass ◽  
...  
Keyword(s):  
Severe Weather ◽  
Special Focus ◽  
Test Bed ◽  
Scanning Strategy ◽  
Engineering Research ◽  
Low Level ◽  
Adaptive Sensing ◽  
Low Levels ◽  
Casa System ◽  
Better Than

Abstract The Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is a multiyear engineering research center established by the National Science Foundation for the development of small, inexpensive, low-power radars designed to improve the scanning of the lowest levels (&lt;3 km AGL) of the atmosphere. Instead of sensing autonomously, CASA radars are designed to operate as a network, collectively adapting to the changing needs of end users and the environment; this network approach to scanning is known as distributed collaborative adaptive sensing (DCAS). DCAS optimizes the low-level volume coverage scanning and maximizes the utility of each scanning cycle. A test bed of four prototype CASA radars was deployed in southwestern Oklahoma in 2006 and operated continuously while in DCAS mode from March through June of 2007. This paper analyzes three convective events observed during April–May 2007, during CASA’s intense operation period (IOP), with a special focus on evaluating the benefits and weaknesses of CASA radar system deployment and DCAS scanning strategy of detecting and tracking low-level circulations. Data collected from nearby Weather Surveillance Radar-1988 Doppler (WSR-88D) and CASA radars are compared for mesoscyclones, misocyclones, and low-level vortices. Initial results indicate that the dense, overlapping coverage at low levels provided by the CASA radars and the high temporal (60 s) resolution provided by DCAS give forecasters more detailed feature continuity and tracking. Moreover, the CASA system is able to resolve a whole class of circulations—misocyclones—far better than the WSR-88Ds. In fact, many of these are probably missed completely by the WSR-88D. The impacts of this increased detail on severe weather warnings are under investigation. Ongoing efforts include enhancing the DCAS data quality and scanning strategy, improving the DCAS data visualization, and developing a robust infrastructure to better support forecast and warning operations.

scholarly journals Evaluation of modified montmorillonite with di-cationic surfactants as efficient and environmentally friendly adsorbents for arsenic removal from contaminated water

2017 ◽  
Vol 18 (2) ◽  
pp. 460-472 ◽  
Author(s):  
E. Shokri ◽  
R. Yegani ◽  
B. Pourabbas ◽  
B. Ghofrani
Keyword(s):  
Contact Time ◽  
Arsenic Removal ◽  
Environmentally Friendly ◽  
Contaminated Water ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Modified Montmorillonite ◽  
Adsorption Capacities ◽  
Modified Adsorbents ◽  
Adsorption Desorption

Abstract In this work, montmorillonite (Mt) was modified by environmentally friendly arginine (Arg) and lysine (Lys) amino acids with di-cationic groups for arsenic removal from contaminated water. The modified Mts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential and thermal analysis. The adsorption of As(V) onto modified Mts as a function of initial As(V) concentration, contact time and solution pH was investigated. The removal efficiency was increased with increasing the As(V) concentration and contact time; however, it was decreased with increasing solution pH. The maximum As(V) adsorption capacities of Mt-Arg and Mt-Lys were 11.5 and 11 mg/g, respectively, which were five times larger than pristine Mt. The high adsorption capacity makes them promising candidates for arsenic removal from contaminated water. The regeneration studies were carried out up to 10 cycles for both modified Mts. The obtained results confirmed that the modified adsorbents could also be effectively used for As(V) removal from water for multiple adsorption – desorption cycles.

scholarly journals Arsenic (III) Removal from a High-Concentration Arsenic (III) Solution by Forming Ferric Arsenite on Red Mud Surface

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 583
Author(s):  
Dongdong He ◽  
Yuming Xiong ◽  
Li Wang ◽  
Wei Sun ◽  
Runqing Liu ◽  
...  
Keyword(s):  
Red Mud ◽  
Arsenic Removal ◽  
Ferric Hydroxide ◽  
Morphological Properties ◽  
Molar Ratio ◽  
Inorganic Pollutants ◽  
High Concentration ◽  
Initial Concentration ◽  
X Ray ◽  
Alkaline Agent

Arsenic (As) is considered one of the most serious inorganic pollutants, and the wastewater produced in some smelters contains a high concentration of arsenic. In this paper, we purified the high-concentration arsenic solution with red mud and Fe3+ synergistically. In this system, arsenite anions reacted with Fe(III) ions to form ferric arsenite, which attached on the surface of red mud particles. The generated red mud/Fe1−x(As)x(OH)3 showed a better sedimentation performance than the pure ferric arsenite, which is beneficial to the separation of arsenic from the solution. The red mud not only served as the carrier, but also as the alkaline agent and adsorbent for arsenic treatment. The effects of red mud dosage, dosing order, pH, and molar ratio of Fe/As on arsenic removal were investigated. The efficiency of arsenic removal increased from a pH of 2 to 6 and reached equilibrium at a pH of 7. At the Fe/As molar ratio of 3, the removal efficiency of arsenic ions with an initial concentration of 500 mg/L reached 98%. In addition, the crystal structure, chemical composition, and morphological properties of red mud and arsenic removal residues (red mud/Fe1−x(As)x(OH)3) were characterized by XRD, XPS, X-ray fluorescence (XRF), SEM-EDS, and Raman spectroscopy to study the mechanism of arsenic removal. The results indicated that most of the arsenic was removed from the solution by forming Fe1−x(As)x(OH)3 precipitates on the red mud surface, while the remaining arsenic was adsorbed by the red mud and ferric hydroxide.

Lake Restoration of Arsenic Pollution by Manganese Ore

2013 ◽  
Vol 726-731 ◽  
pp. 1659-1663
Author(s):  
Ning Xin Chen ◽  
Yong Bing Huang ◽  
Jing Dong
Keyword(s):  
Removal Efficiency ◽  
Adsorption Process ◽  
Arsenic Removal ◽  
Freundlich Isotherm ◽  
Order Reaction ◽  
Contaminated Water ◽  
Manganese Ore ◽  
Arsenic Pollution ◽  
First Order ◽  
Acidic Conditions

Using manganese ore coated with small stones to adsorb arsenic from the contaminated water samples of Yangzonghai Lake, and several factors that may have impacts on the arsenic removal efficiency are analyzed. The result shows that the new adsorbent material has a great effect on arsenic removal. Temperature's effect on arsenic removal efficiency is not obvious. The arsenic removal efficiency increased dramatically in accordance with residence time within 0-660s, and then stabilized. The adsorption process is better when conducted in acidic conditions, the maximum adsorption rate reached 83.0% with the pH of 3.0 and it reached the minimum value of 14.7% when pH is 10. Fe3+ and Ca2+ can slightly promote manganese ore's adsorption of arsenic, and with anions CO32-, SiO32- , efficiency was slightly reduced. When fitting the kinetics data of arsenic removal by coated manganese ore, the adsorption process is correspondent with first-order reaction kinetics model. The adsorption isotherm is more close to the Freundlich isotherm model.

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