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.

Speciation and Removal of Arsenic in column packed with chitosan

2006 ◽  
Vol 1 (4) ◽  
Author(s):  
Martha Benavente ◽  
Marcos Arévalo ◽  
Joaquín Martínez
Keyword(s):  
Arsenic Removal ◽  
Arsenic Speciation ◽  
Packed Column ◽  
Arsenic Concentration ◽  
Breakthrough Curves ◽  
Arsenic Adsorption ◽  
Major Species ◽  
Standard Solution ◽  
Ph Range ◽  
Removal Of Arsenic

The arsenic speciation and arsenic removal in chitosan packed column were studied. Arsenic removal experiments were carried out with an arsenic standard solution (1.0 mg/l) and drilled well water samples from Limon Mine Community at different pH, water flowrate, and volume of adsorbent material. The simulation of arsenic speciation was carried out at a pH range from 0 to 12, a temperature of 25ºC, a pE equal to 4, and a total arsenic concentration of 1.34 x 10-5 mol kg-1. According to speciation calculations arsenic is found mainly in oxidized form in the conditions of Limon Mine’s drilled well waters, dihydrogen arsenate ion (H2AsO4-), and hydrogen arsenate ion (HAsO42-) being the major species. The experiments showed that arsenic adsorption depends mainly on the pH as well as the activity of functional groups that compose the chitosan structure. At pH 3 and volume of adsorbent material of 337.8 cm3 an adsorption of 94% was obtained from arsenic standard solution, and the arsenic present in the Limon Community’s water was almost totally removed at pH 3 and 7. The use of the results for designing purposes demands the breakthrough curves for chitosan to be determined.

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.

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.

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.

scholarly journals Adsorption of arsenic and phosphate from groundwater onto a calcined laterite as fixed bed in column experiments

2020 ◽  
Vol 8 (2) ◽  
pp. 227-243
Author(s):  
Yacouba Sanou ◽  
Raymond Kabore ◽  
Samuel Pare
Keyword(s):  
Arsenic Removal ◽  
Arsenic Concentration ◽  
Fixed Bed ◽  
Column Experiments ◽  
Arsenic Adsorption ◽  
Experimental Conditions ◽  
Ph Values ◽  
Naoh Solution ◽  
Removal Of Arsenic ◽  
Maximum Removal

This work was focused on laterite soil as adsorbent for the removal of arsenic and phosphate from groundwater using column experiments. Results revealed a decrease of arsenic removal efficiency from 100 to 79% with flow rate increasing. Maximum removal of 100% for arsenic and 85% for phosphates was obtained for pH values between 3.5 and 6. The increase of initial arsenic concentration and phosphate amount caused an increase of arsenic adsorption up to 24 µg/g while 58.5 µg/g for phosphate. NaOH solution could desorb 86.8% of arsenic and the reuse of regenerated laterite indicated its efficiency in same experimental conditions.

scholarly journals Assessment of Aspergillus niger Strain’s Suitability for Arsenate-Contaminated Water Treatment and Adsorbent Recycling via Bioextraction in a Laboratory-Scale Experiment

2020 ◽  
Vol 8 (11) ◽  
pp. 1668
Author(s):  
Eva Duborská ◽  
Kinga Szabó ◽  
Marek Bujdoš ◽  
Hana Vojtková ◽  
Pavol Littera ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Arsenic Removal ◽  
Culture Media ◽  
Arsenic Concentration ◽  
Contaminated Water ◽  
Biotechnology Research ◽  
Cultivation Period ◽  
Ferric Oxyhydroxide ◽  
The Common ◽  
Scale Experiment

In this work, the viability of bioaccumulation and bioextraction processes for arsenic removal from contaminated waters, as well as the recycling of arsenate-treated amorphous ferric oxyhydroxide adsorbent (FeOOH) were evaluated using the common soil microscopic filamentous fungus Aspergillus niger. After treating the contaminated arsenate solution (100 mg As L−1) with FeOOH, the remaining solution was exposed to the growing fungus during a static 19-day cultivation period to further decrease the arsenic concentration. Our data indicated that although the FeOOH adsorbent is suitable for arsenate removal with up to 84% removal efficiency, the fungus was capable of accumulating only up to 13.2% of the remaining arsenic from the culture media. This shows that the fungus A. niger, although highly praised for its application in environmental biotechnology research, was insufficient for decreasing the arsenic contamination to an environmentally acceptable level. However, the bioextraction of arsenic from arsenate-treated FeOOH proved relatively effective for reuse of the adsorbent. Due to its production of acidic metabolites, which decreased pH below 2.7, the fungal strain was capable of removing of up to 98.2% of arsenic from the arsenate-treated FeOOH adsorbent.

Arsenic Removal via Cellulose-Based Organic/Inorganic Hybrid Materials from Drinking Water

2012 ◽  
Vol 730-732 ◽  
pp. 563-568
Author(s):  
Catarina Martins ◽  
Rui F. Duarte ◽  
Maria C.F. Magalhães ◽  
Dmitry Evtuguin
Keyword(s):  
Aqueous Solutions ◽  
Hybrid Materials ◽  
Arsenic Removal ◽  
Sol Gel ◽  
Arsenic Concentration ◽  
Cellulose Fiber ◽  
Silica Network ◽  
Bleached Pulp ◽  
Removal Of Arsenic

Cellulose/silica derived hybrids materials (CSH), functionalized with aluminium, calcium, and propylammonium ions, were tested for their possible use in the removal of arsenic from aqueous solutions with controlled compositions to levels lower than 10 μg As/L. CSH were synthesized by sol-gel method using bleached pulp, as source of cellulose fiber, and tetraethoxysilane (TEOS) as main silica precursor. The silica network, made in situ, contained various anchored cations such as propylammonium (CSH-PA), aluminium (CSH-Al) and, calcium (CSH-Ca). Thin films or mesoparticles of silica were deposited on cellulose fibers as shown by SEM and XRD. These hybrid materials were immersed in controlled ionic strength aqueous solutions with arsenic concentrations lower than 0.2 mg As/L. The best performance was shown by CSH-PA that was able to remove a maximum of 20 % of the total arsenic concentration.

scholarly journals The Influence of Dosing Modes of Coagulate on Arsenic Removal

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Zhibin Zhang ◽  
Jinxiang Li ◽  
Cuizhen Sun ◽  
Yanhao Zhang ◽  
Lilong Huang ◽  
...  
Keyword(s):  
Particle Size ◽  
Arsenic Removal ◽  
Arsenic Speciation ◽  
Contaminated Water ◽  
Distribution Analysis ◽  
Hydrous Oxides ◽  
Stretching Vibration ◽  
Ft Ir ◽  
Single Dosing ◽  
High Arsenic

Three different dosing modes, including one single dosing mode and two sequential dosing modes, were applied in high-arsenic contaminated water treatment. The results illustrated that the As (V) soluble and the As (V) nonspecifically sorbed were the insignificant species from Fe-As (V) samples in the sequential dosing mode, while they were higher in the single dosing mode. However, it could be further concluded that the mobility of the Fe-As (V) in sequential dosing mode was greater than that in single dosing mode. Besides, the main arsenic speciation governing the arsenic-borne coagulates was the As (V) associated with poorly crystalline hydrous oxides of Fe in sequential or single dosing mode. Moreover, the particle size distribution analysis indicated that the sequential dosing mode was more prevalent in neutralizing and adsorbing the As (V) compared with the single dosing mode. In the FT-IR spectra, the presence of arsenic was highlighted by a well resolved band at 825–829 cm−1. The positions of the As–O stretching vibration bands were shifted gradually as the dosing mode changed from the single to the sequential. This result could be related to the distribution of arsenic speciation in different dosing modes.

scholarly journals Development of ion-imprinted cryogels for selective removal of arsenic from environmental waters

2019 ◽  
Vol 9 (4) ◽  
pp. 4119-4125
Keyword(s):  
Adsorption Capacity ◽  
Arsenic Removal ◽  
Removal Rate ◽  
Anthropogenic Activities ◽  
Arsenic Concentration ◽  
Environmental Water ◽  
Maximum Adsorption Capacity ◽  
Environmental Waters ◽  
Ion Imprinted ◽  
Removal Of Arsenic

Arsenic present by nature as metalloid, having transportability in the environment via diverse sources. Because of both natural processes and anthropogenic activities, arsenic is found in environmental water sources. The aim of this study is to design ion-imprinting-based cryogel adsorbents for the removal of arsenic species from environmental waters. Since trivalent arsenic exhibit a high afgfinity for sulfhydryl groups, cysteine-based functional monomer, i.e. MAC, was synthesized and MAC–As(III) complex was prepared. Ionimprinted polymeric adsorbents were fabricated via cryopolymerization. Elemental analysis studies have shown that the cryogel monolith contains 192.8 μmol/g mol MAC/g polymer. The maximum adsorption capacity of ion-imprinted cryogels at an initial arsenic concentration of 10 ppm was found to be 372.5 μg/g at pH 8.0. Arsenic removal rate of the imprinted cryogels from environmental water sample was determined as 94.8% In the studies carried out for the removal of arsenic from the environmental waters, 94.8% removal efficiency was achieved. Reusability assays of ion-imprinted cryogels were performed and there was no significant decrease in adsorption capacity.

Using ZnO Nanorods Coated Porous Ceramic Monolith to Remove Arsenic from Groundwater

2017 ◽  
Vol 751 ◽  
pp. 756-765 ◽  
Author(s):  
Kannika Khwamsawat ◽  
Jukkrit Mahujchariyawong ◽  
Supamas Danwittayakul
Keyword(s):  
Water Sample ◽  
Arsenic Removal ◽  
Porous Ceramic ◽  
Zno Nanorods ◽  
Arsenic Concentration ◽  
Solution Concentration ◽  
Growth Time ◽  
Arsenic Content ◽  
Growth Solution ◽  
Nano Adsorbent

Arsenic contaminants in drinking water pose a threat to human health. In this study, we report the use of nanotechnology to enhance the efficiency of arsenic removal. In here, zinc oxide (ZnO) has been selected for this application due to its environmentally friendly to human being. One-dimensional ZnO nanorods were grown on porous ceramic substrate by hydrothermal technique. The monolith nano-adsorbents were investigated using field emission scanning electron microscope (FESEM, Hitachi, SE-8030), while phase compositions and specific surface area were examined by x-ray diffractometer (XRD, PAnalitical, X’Pert PRO). Experiments of arsenic adsorption were conducted by using 200 ppb arsenic concentration solution with a continuously stirring system. After the adsorption, each water sample was then measured the arsenic content by inductively coupled plasma-optical emission spectroscope (ICP-OES) as compare to the original water sample to calculate the percentage of arsenic removal. We found that morphology of nano-adsorbent on using the growth solution concentration of 20mM of growth solution concentration and 20 hours of growth time showed the highest density of ZnO hexagonal nanorods with about 100 nm in diameter. The optimization studies obtained 30 minute of adsorption time, pH as 7. This nano-adsorbent exhibited about 98% of arsenic removal. For the comparison with commercial adsorbent (As600), ZnO nano-adsorbent has a better efficiency. The strong competitive ion on the arsenic removal was PO43-. Moreover, the real groundwater after treatment doesn’t have any toxic residue. Therefore, ZnO nanorods coated on porous ceramic can be the candidate material for arsenic removal from groundwater.

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