{"id":1613,"date":"2020-05-20T08:17:32","date_gmt":"2020-05-20T13:17:32","guid":{"rendered":"http:\/\/www.journalnano.org\/?p=1613"},"modified":"2020-05-20T08:25:32","modified_gmt":"2020-05-20T13:25:32","slug":"arsenite-removal-with-fe3o4-mnfe2o4-and-cofe2o4-nanoparticles","status":"publish","type":"post","link":"http:\/\/www.journalnano.org\/?p=1613","title":{"rendered":"Arsenite removal with Fe3O4, MnFe2O4 and CoFe2O4 Nanoparticles"},"content":{"rendered":"<div id=\"fb-root\"><\/div>\r\n<script>(function(d, s, id) {\r\n  var js, fjs = d.getElementsByTagName(s)[0];\r\n  if (d.getElementById(id)) return;\r\n  js = d.createElement(s); js.id = id;\r\n  js.src = \"\/\/connect.facebook.net\/en_GB\/all.js#xfbml=1\";\r\n  fjs.parentNode.insertBefore(js, fjs);\r\n}(document, \"script\", \"facebook-jssdk\"));<\/script>\r\n<fb:share-button href=\"http:\/\/www.journalnano.org\/?p=1613\" type=\"icon_link\"\r\nstyle=\"padding-top:0px;\r\npadding-right:0px;\r\npadding-bottom:0px;\r\npadding-left:0px;\r\nmargin-top:0px;\r\nmargin-right:0px;\r\nmargin-bottom:0px;\r\nmargin-left:0px;\r\n\">\r\n<\/fb:share-button><\/br><p><span style=\"font-size: 24px;\"><strong>Using fixed bed column and magnetic filtration<\/strong><\/span><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Morales-Amaya C.G.<\/b><\/span><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Alarc\u00f3n-Herrera M.T.<\/b><\/span><\/p>\n<p class=\"p2\"><span style=\"font-size: 14px;\">Departamento de Ingenier\u00eda Sustentable, CIMAV, CIMAV 110, Ejido Arroyo Seco, C.P. 34147, Durango, Dgo. M\u00e9xico.\u00a0<\/span><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Astudillo-S\u00e1nchez P.D.<\/b><\/span><\/p>\n<p class=\"p2\"><span style=\"font-size: 14px;\">Departamento de Ciencias Basicas y Aplicadas, Centro Universitario de Tonal\u00e1. Av. Nuevo perif\u00e9rico Ote. 45425, Tonal\u00e1, Jalisco.<\/span><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Lozano-Morales S.A.<\/b><\/span><\/p>\n<p class=\"p2\"><span style=\"font-size: 14px;\">C\u00e1tedras-CONACYT-Centro de Investigaci\u00f3n en Qu\u00edmica Aplicada , Blvd. Enrique Reyna 140, Saltillo, C. P. 25294.Coahuila, M\u00e9xico.<\/span><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Licea-Jim\u00e9nez L.<\/b><\/span><\/p>\n<p class=\"p2\"><span style=\"font-size: 14px;\">CIMAV, S.C. Alianza Norte 202, Parque de Investigaci\u00f3n e Innovaci\u00f3n Tecnol\u00f3gica PIIT C.P. 66628 Apodaca, NL., M\u00e9xic<i>o.<\/i><\/span><i> <\/i><\/p>\n<p class=\"p1\"><span style=\"font-size: 16px;\"><b>Teynoso-Cuevas L.<\/b><\/span><\/p>\n<p class=\"p2\"><span style=\"font-size: 14px;\">C\u00e1tedras-CONACYT. Departamento de Ingenier\u00eda Sustentable, CIMAV, Calle CIMAV 110, Ejido Arroyo Seco, C.P. 34147, Durango, Dgo. M\u00e9xico.<\/span><\/p>\n<blockquote>\n<p class=\"p1\"><span class=\"s1\" style=\"color: #808080; font-size: 16px;\"><b><i> This work evaluates the ability of nanoparticles (NPs) to remove arsenic (As<sup>+3<\/sup>) from water. Metallic NPs of Fe3O4, as well as bimetallic NPs of CoFe2O4 and MnFe2O4, were synthesized by chemical coprecipitation. The three types of NPs consist of nanocrystals with high monodispersity and excellent stoichiometry, and show superparamagnetic properties at room temperature. X-ray diffraction (DXR) shows that the NPs have the characteristic intense peak of inverse spinel-like crystalline phase in the 311 plane, which is typical of a ferrite. Scanning Electron Microscopy (SEM) shows nanocrystals with uniform quasi-spherical morphology; surface area for the NPs was 168.8 m<sup>2<\/sup>\/g (MnFe2O4), 198.6 m2\/g (CoFe2O4), and 158.8 m<sup>2<\/sup>\/g (Fe3O4). The size of the NPs, determined by Dynamic Light Scattering (DLS), averaged 12-50 nm. The removal of As<sup>+3<\/sup> from water was carried out in fixed-bed columns with continuous flow and magnetic filtration. Magnetic separation favored the filtration and separation of the NPs. The adsorption capacity results show that it is possible to reduce the concentration of As<sup>+3<\/sup> below the maximum permissible limit (25 \u00b5g\/L) established by the official Mexican standard for water for human consumption (NOM-127-SSA1-1994), and that 0.1 g\/L of the NPs can achieve nearly complete removal. Adsorption results were adjusted with an R<sup>2<\/sup>= 0.99 to the Freundlich and Langmuir isotherms. The adsorption capacity of the NPs was 115 (MnFe2O4), 130 (CoFe2O4), and 43,450 mg\/g (Fe3O4).<\/i><\/b><\/span><\/p>\n<\/blockquote>\n<p class=\"p2\" style=\"text-align: justify;\"><span style=\"font-size: 36px;\">A<\/span>rsenic (As) contamination in groundwater is a global threat. It is estimated that more than 300 million people worldwide drink water with As levels that exceed the permissible limit (10 \u00b5g\/L) [1]. Many parts of Latin America are among the most severely polluted regions of the world [2].<\/p>\n<p class=\"p2\" style=\"text-align: justify;\">The last decade brought new findings of As in water for human consumption in Argentina, Brazil, Chile, Colombia, Ecuador, El Salvador, Guatemala, Mexico, Nicaragua, and Peru [2]. More than 4.5 million people in Latin America are chronically exposed to concentrations greater than 50 \u00b5g\/L of As. McClintock et al., 2012, and the World Health Organization (WHO), 2011, outlined the health effects of people who are chronically exposed to As in drinking water. Vascular diseases (premature heart attack) stand out in their analysis, as well as respiratory diseases, skin lesions and lung and bladder cancer [3,4].<\/p>\n<p class=\"p2\" style=\"text-align: justify;\">The application of nano-adsorbents for water treatment has become increasingly common, due to a high removal efficiency for As [5]. The aim of this study was to synthesize low-cost metal nanoparticles that can be used in water treatment, specifically in the removal of As. In this work, the technical and economic viability of the three metal nanoparticles was synthesized and evaluated, MxFe3-xO4 (where M=Co and\/or Mn and x=2).<\/p>\n<p class=\"p4\" style=\"text-align: justify;\"><strong><span style=\"font-size: 24px;\">Methodology<\/span><\/strong><\/p>\n<p class=\"p2\" style=\"text-align: justify;\"><span style=\"font-size: 20px;\"><i>NPs Synthesis<\/i><\/span><\/p>\n<p class=\"p2\" style=\"text-align: justify;\">The NPs were prepared by chemical coprecipitation [6]. For the synthesis of MnFe2O4 NPs, Fe(NO3)3\u20229H2O and MnSO4\u2022H2O were dissolved, with a stoichiometry ratio of 2:1, in 5 mL of deionized water and 1 mL of HCl at 1 M. The solution was mixed and vigorously stirred. Then, 100 mL of NaOH was added dropwise to 3 M. Once the addition was complete, it was brought to 90 \u00b0C for 60 min. This same procedure was applied for CoFe2O4 NPs, using CoSO4\u20227H2O and Fe(NO3)3\u20229H2O as precursors. Fe(NO3)3\u20229H2O and FeCl2\u20224H2O were used to produce Fe3O4. NPs were then allowed to cool until reaching thermal equilibrium with the environment. The NPs obtained were recovered from the solution with the help of a magnet and repeatedly rinsed. Afterward, the values of pH were adjusted to 6, 7, 8, and 8.5. Finally, the products were baked at 50 \u00b0C for 48 h and subsequently ground.<\/p>\n<p class=\"p2\"><span style=\"font-size: 20px;\"><i>NPs characterization<\/i><\/span><\/p>\n<p class=\"p2\" style=\"text-align: justify;\">The morphology and dimensions were ef the NPs were observed through scanning electron microscopy (SEM), using a FEI Nova NanoSem200 with a low vacuum detector. A PANalytical X-ray diffractometer model Empyream of Malvern with a K-Alpha Cu anode of 1.54 nm, at an amperage of 40 mA and a voltage of 45 kV, with a scanning step of 0.02 in 2\u03b8 degrees, was used to know the crystal structure of the NPs. The values of the specific surface area were determined by the Brunauer, Emmett, and Teller (BET) method, using the Quantachrome Nova Corporation 1000 series equipment. The samples were degassed in vacuum at 150 \u00b0C for 10 h. Also, X-ray photoelectron spectrometry (XPS) analyses were carried out with a Thermo Scientific Escalab 250Xi instrument. The base pressure during analysis was ~10<sup>\u221210<\/sup> mbar and the photoelectrons were generated with the Al K\u03b1 (1486.68 eV) X-ray source with monochromator and a spot size of 650 \u00b5m. The X-ray voltage and power were 14 kV and 350 W, respectively. The acquisition conditions for the high-resolution spectra were 20 eV pass energy, 45\u00ba take-off angle and 0.1 eV\/step. The recorded photoelectrons peaks were analyzed with the Avantage software V 5.41. The magnetic properties of the NPs were analyzed at room temperature with an AGM MICROMAG magnetometer.<\/p>\n<p class=\"p2\" style=\"text-align: justify;\"><span style=\"font-size: 20px;\"><i>Absorption propierties<\/i><\/span><\/p>\n<p class=\"p2\" style=\"text-align: justify;\">To evaluate the adsorption of As+3, a stock solution of NaAsO2 was prepared at a concentration of 40 \u03bcg\/L, and divided into three containers for testing, each with 1 L of solution. After adding 0.1 g of the adsorbent NPs, the pH of the solutions were adjusted to 6, 7, and 8 by aqueous solutions of NaOH and HNO3. The solutions were stirred at room temperature for 10 min, then transferred to the continuous flow column of a magnetic filtration column with high gradient magnetic separation (HGMS). The filtered solutions were stored in jars for further analysis. An HGMS device comprises a bed of magnetically susceptible cables placed inside an electromagnet or external magnetic fields. When a magnetic field is applied across the column, the wires dehomogenize the magnetic field in the column, producing large field gradients around the wires that attract magnetic particles to their surfaces and trap them there [7]. For the successful collection o<\/p>\n<p class=\"p2\" style=\"text-align: justify;\">f magnetic particles by HGMS, the magnetic forces that attract the particles to the wires must dominate the entrainment of the fluid, the gravitational, inertial and fusion forces as the suspension of the particles flow through the separator. The particles were tested in continuous flow columns with magnetic transmission. In Figure 1, the diagram of the column of the magnetic transmission is shown.<\/p>\n<p><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure3-copy.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1617 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure3-copy.jpg\" alt=\"\" width=\"600\" height=\"383\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure3-copy.jpg 600w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure3-copy-300x192.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a><\/p>\n<p><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure4.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1616 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure4.jpg\" alt=\"\" width=\"600\" height=\"311\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure4.jpg 600w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/figure4-300x156.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a><\/p>\n<p class=\"p1\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\"><span class=\"s1\"><b>Figure 1. <\/b><\/span><b> <\/b><b>a) <\/b>Scheme and b) photography of magnetic separator and magnetic filtration column.<\/span><\/p>\n<p class=\"p2\" style=\"text-align: justify;\">The total concentrations of As were determined by a GBS atomic absorption spectrophotometer (Avanta Sigma model) coupled to a hydride generator (HG-AAS) with flame (air-acetylene). Samples were prepared with 3 mL of concentrated HCl and 3 mL of KL, allowed to stand for 3 h for later determination.<\/p>\n<p class=\"p4\" style=\"text-align: justify;\"><strong><span style=\"font-size: 24px;\">Results and Discussion<\/span><\/strong><\/p>\n<p class=\"p2\" style=\"text-align: justify;\">Brunauer-Emmett-Teller (BET) surface analysis determined that the specific surface area values of MnFe2O4, CoFe2O4, and Fe3O4 were 198.6, 188.8, and 158.8 m2\/g, respectively.<\/p>\n<p class=\"p2\" style=\"text-align: justify;\">Figure 2 shows the SEM images of a) MnFe2O4,<span class=\"Apple-converted-space\">\u00a0 <\/span>b) CoFe2O4 <span class=\"Apple-converted-space\">\u00a0 <\/span>and c) Fe3O4, where it is observed that the samples consist of nanoparticles with relatively uniform size and quasi-spherical morphology. Average sizes of 38, 22 and 57 nm were obtained for the NPs of MnFe2O4, CoFe2O4 and Fe3O4, respectively.<\/p>\n<p class=\"p2\" style=\"text-align: justify;\"><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Sin-ti\u0301tulo.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1618 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Sin-ti\u0301tulo.jpg\" alt=\"\" width=\"921\" height=\"283\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Sin-ti\u0301tulo.jpg 921w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Sin-ti\u0301tulo-300x92.jpg 300w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Sin-ti\u0301tulo-768x236.jpg 768w\" sizes=\"(max-width: 921px) 100vw, 921px\" \/><\/a><\/p>\n<p class=\"p1\"><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 2.<\/b><\/span><span class=\"s2\"><b><span class=\"Apple-converted-space\">\u00a0 <\/span><\/b><\/span>Scanning electron microscopy (SEM) of NPs:<span class=\"Apple-converted-space\">\u00a0 <\/span>a) MnFe2O4,<span class=\"Apple-converted-space\">\u00a0 <\/span>b) CoFe2O4 and c) Fe3O4.<\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The XRD patterns of MnFe2O4, CoFe2O4, and Fe3O4 are shown in Figure 3a-c. Figure 3a corresponds to the XRD pattern of the sample of MnFe2O4, where the peaks 2\u03b8 of 30.31\u00b0, 36.60\u00b0, 44.57\u00b0, 58.68\u00b0, 57.12\u00b0, and 65.78\u00b0 are indexed to planes (220), (311), (400), (511) and (440), respectively; corresponding to the cubic structure centered on the face of MnFe2O4, according to the<span class=\"Apple-converted-space\">\u00a0 <\/span>card JCPDS- 742403 of the International center diffraction data.<\/p>\n<p class=\"p1\" style=\"text-align: justify;\">Figure 3b shows the diffraction peaks for the sample of CoFe2O4 located at the values of 2\u03b8 at 18\u00b0, 30\u00b0, 36\u00b0, 43\u00b0, 57\u00b0, and 62\u00b0 with the respective crystal planes (111), (220), (311), (400), (511) and (400), respectively; corresponding with the card JCPDS-22-1086 of the International center diffraction data [8].<\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The XRD pattern of Figure 3c corresponds to the sample of Fe3O4, which contains a high coincidence with the values and intensities of the JCPDS-01-084 3854 sheets of the International center diffraction data. The sample presented peaks in 2\u03b8 corresponding to 20.5\u00b0, 30.31\u00b0, 36.60\u00b0, 44.57\u00b0, 54\u00b0, 57.12\u00b0, and 65.78\u00b0, which are indexed at (111), (220), (311), ( 400), (422), (511) and (440) planes, respectively, correspond to a cubic unitary cell, characteristic of a cubic spinel structure [9].<\/p>\n<p><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-3-2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1619 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-3-2.jpg\" alt=\"\" width=\"733\" height=\"583\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-3-2.jpg 733w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-3-2-300x239.jpg 300w\" sizes=\"(max-width: 733px) 100vw, 733px\" \/><\/a><\/p>\n<p class=\"p1\"><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 3.<\/b><\/span><span class=\"s2\"><b><span class=\"Apple-converted-space\">\u00a0 <\/span><\/b><\/span>XRD image of: MnFe2O4, b) CoFe2O4 and c) Fe3O4.<\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">Figure 4 shows the peaks of the binding energies of each element, as determined by the XPS analysis, where the corresponding to the surface molar ratio of Fe\/Mn and Fe\/Co was according to MnFe2O4, and CoFe2O4 was 2:1, which coincides with the expected, since, is the ratio of metal ions in the solution.<a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure4-2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1620 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure4-2.jpg\" alt=\"\" width=\"600\" height=\"416\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure4-2.jpg 600w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure4-2-300x208.jpg 300w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure4-2-145x100.jpg 145w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/a><\/p>\n<p class=\"p1\"><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 4. <\/b><\/span>XPS for Fe3O4, CoFe2O4, and MnFe2O4.<\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The hysteresis cycle of NPs was studied to verify paramagnetic behavior. The hysteresis curve in these NPs is shown in Figure 5, in which the hysteresis cycle is narrow, typical of soft magnetic materials, the magnetization of MnFe2O4, CoFe2O4 and Fe3O4 was 48.39, 58.74 and 28.03 emu\/g, correspondingly. These properties make adsorbents easily separate from solution when an external magnetic field is applied.<a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure5.png\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1621 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure5.png\" alt=\"\" width=\"272\" height=\"228\" \/><\/a><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 5.<\/b><\/span><span class=\"s2\"><b><span class=\"Apple-converted-space\">\u00a0 <\/span><\/b><\/span>Hysteresis cycle of MnFe2O4, CoFe2O4 and Fe3O4.<\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The zeta potential, as a function of the pH in contact with the synthesized NPs, is shown in Figure 6. The difference is negligible between the pH values over the zeta potential in CoFe2O4 and MnFe2O4, in contrast with Fe3O4. However, the charge of the NPs at pH 2 value is positive, as shown in Figure 6. For the case of pH 4, 6, 8, 8.5, and 10, in the NPs the surface of these is negative, so the isoelectric point of these materials would be at pH 2.<a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-6-copy.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1622 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-6-copy.jpg\" alt=\"\" width=\"537\" height=\"474\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-6-copy.jpg 537w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure-6-copy-300x265.jpg 300w\" sizes=\"(max-width: 537px) 100vw, 537px\" \/><\/a><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 6.<\/b><\/span><span class=\"s2\"><b><span class=\"Apple-converted-space\">\u00a0 <\/span><\/b><\/span>Zeta potential as a function of pH of<span class=\"Apple-converted-space\">\u00a0 <\/span>MnFe2O4,<span class=\"Apple-converted-space\">\u00a0 <\/span>CoFe2O4 and<span class=\"Apple-converted-space\">\u00a0 <\/span>Fe3O4.<\/span><\/p>\n<p class=\"p3\" style=\"text-align: justify;\"><span style=\"font-size: 20px;\"><i>Effect of the removal of As<sup>+3<\/sup> in continuous flow with MnFe2O4, CoFe2O4 and Fe3O4<\/i><\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">As described in the methodology section above, the experiments were carried out in a liter of solution with an initial concentration of 40 \u00b5g\/L of As<sup>+3<\/sup>, and with an adsorbent dose of<span class=\"Apple-converted-space\">\u00a0 <\/span>0.1 g\/L. The solutions and nanoparticles were stirred for 10 minutes at 450 rpm, after which the continuous flow in the HGMS device was 100 mL\/min. Magnetic separation favored the filtration and separation of the NPs.<\/p>\n<p class=\"p1\" style=\"text-align: justify;\">Figure 7 shows the comparison chart of the 3 NPs in the removal of As+3 in continuous flow, in the Table 1 shows the results of the removal of As+3 with each of the NPs. The results of the adsorption capacity of As+3 as a function of pH (6, 7 and 8) are reported in Table 2.<\/p>\n<p class=\"p1\" style=\"text-align: justify;\"><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1624 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy.jpg\" alt=\"\" width=\"1152\" height=\"215\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy.jpg 1152w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy-300x56.jpg 300w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy-1024x191.jpg 1024w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.09-AM-copy-768x143.jpg 768w\" sizes=\"(max-width: 1152px) 100vw, 1152px\" \/><\/a><a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure7-copy.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1623 size-full\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure7-copy.jpg\" alt=\"\" width=\"461\" height=\"384\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure7-copy.jpg 461w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Figure7-copy-300x250.jpg 300w\" sizes=\"(max-width: 461px) 100vw, 461px\" \/><\/a><span style=\"font-size: 12px;\"><span class=\"s1\"><b>Figure 7.<\/b><\/span><span class=\"s2\"><b>\u00a0<\/b><\/span> Removal<span class=\"Apple-converted-space\">\u00a0 <\/span>As<sup>+3<\/sup> in continuous flow.<\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">It is shown both in the graph and in the table, that the removal of As+3 with the use of NPs as adsorbents in continuous flow occurs in the first 10 minutes, the removal efficiencies for MnFe2O4 and CoFe2O4 are greater than 90%, on the other hand, the Fe3O4 removal percentage is closer to 85%. Nevertheless, the final concentrations of the three experiments are able to enter the NOM-1994 standards for water for human consumption [10], which makes this type of NPs a technology with high technical feasibility in the removal of As+3 in continuous flow.<\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The effect of pH on the adsorption of ions in the samples with Fe3O4, MnFe2O4, and CoFe2O4 is shown in table 2. The solution reaches As+3 equilibrium after only 10 min, probably because the NPs have a negative surface charge (approximately -98 mV for MnFe2O4, -90 mV for CoFe2O4, and -75 mV for Fe3O4). H3AsO3 is positively charged in the pH range of 6-8 used here, and electrostatic attraction te the NPs accounts for the high adsorption efficiency of As<sup>+3<\/sup>.<a href=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-1625 size-large\" src=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy-1024x183.jpg\" alt=\"\" width=\"1024\" height=\"183\" srcset=\"http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy-1024x183.jpg 1024w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy-300x54.jpg 300w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy-768x137.jpg 768w, http:\/\/www.journalnano.org\/wp-content\/uploads\/2020\/05\/Screen-Shot-2020-05-20-at-8.15.22-AM-copy.jpg 1148w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/a><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The adsorption capacity of As<sup>+3 <\/sup>remained similar in the range of pH studied; this is possible because the lack of competition from the hydroxyl groups (OH<sup>&#8211;<\/sup>) that were generated in the adsorption processes, which kept the adsorption sites active, and as well as the non-deprotonation of the NPs [11]. This effect involves a two-step ligand exchange reaction: first, the hydroxyl group of the metal hydroxide is protonated; then, the H2O ligand is replaced with the oxyanion, so the adsorption is affected by protonation of the pH-dependent metal hydroxide surfaces. The affinity differences of the adsorption between the oxyanion species are generally small; this is usually attributed to the deprotonation of the surface of the metal hydroxides with the increase of pH [12]. The surfaces of our NPs play an essential role in the electrostatic interaction towards As<sup>+3<\/sup>, for the exchange of ligands.<\/p>\n<p class=\"p5\" style=\"text-align: justify;\"><span style=\"font-size: 24px;\"><strong>Conclusions<\/strong><\/span><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">This work presents nanoparticles (NPs) with the potential for removing As+3 ions from water for human consumption. Adsorption capacity measurements show that water carrying 40 \u03bcg\/L of As<sup>+3<\/sup> can be brought not only below the official Mexican standard (25 \u03bcg\/L), but also below of the WHO standard (10 \u03bcg\/L). The adsorbents MnFe<sub>2<\/sub>O4 and CoFe2O4 showed better performance than Fe3O4. Within the tested range, pH has no significant effect on the adsorption of As<sup>+3<\/sup>, because As<sup>+3<\/sup> was found as H3AsO3<sup>0<\/sup> in this range.<\/p>\n<p class=\"p5\" style=\"text-align: justify;\"><strong>ACKNOWLEDGEMENTS<\/strong><\/p>\n<p class=\"p1\" style=\"text-align: justify;\">This work was supported with Project No. 267666 of the FONCICYT CONACYT-INNOVATE UK 2015. Likewise, thanks to FORDECYT project No. 297116: \u201cWater Consortium.\u201d To CONACYT for its support with the scholarship 486760.<\/p>\n<p class=\"p1\" style=\"text-align: justify;\">The acknowledgments also To M.S.A Luis Arturo Torres-Casta\u00f1\u00f3n, for all the analytical facilities and collaboration in analytical determinations.<\/p>\n<p><strong><span style=\"font-size: 28px;\">References<\/span><\/strong><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[1] R. Quansah, F.A. Armah, D.K. Essumang, I. Luginaah, E. Clarke, K. Marfoh, S.J. Cobbina, E. Nketiah-Amponsah, P.B. Namujju, S. Obiri, M. Dzodzomenyo, Association of arsenic with adverse pregnancy outcomes\/infant mortality: A systematic review and meta-analysis, Environ. Health Perspect. 123 (2015) 412\u2013421. doi:10.1289\/ehp.1307894.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[2] R. Kumar, M. Patel, P. Singh, J. Bundschuh, C.U. Pittman, L. Trakal, D. Mohan, Emerging technologies for arsenic removal from drinking water in rural and peri-urban areas: Methods, experience from, and options for Latin America, Sci. Total Environ. 694 (2019) 133427. doi:10.1016\/J.SCITOTENV.2019.07.233.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[3] T.R. McClintock, Y. Chen, J. Bundschuh, J.T. Oliver, J. Navoni, V. Olmos, E.V. Lepori, H. Ahsan, F. Parvez, Arsenic exposure in Latin America: Biomarkers, risk assessments and related health effects, Sci. 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Sillanp\u00e4\u00e4, Water purification using magnetic assistance: A review, J. Hazard. Mater. 180 (2010) 38\u201349. doi:10.1016\/j.jhazmat.2010.04.105.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[8] S. Zhang, H. Niu, Y. Cai, X. Zhao, Y. Shi, Arsenite and arsenate adsorption on coprecipitated bimetal oxide magnetic nanomaterials: MnFe2O4 and CoFe2O4, Chem. Eng. J. 158 (2010) 599\u2013607. doi:10.1016\/j.cej.2010.02.013.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[9] L.C.M. Scapim, S.B. Borges, J.N. de Paula, L.P. Ferreira, P.R. de Almeida III, S\u00cdNTESE E CARACTERIZA\u00c7\u00c3O DE NANOMAGNETITA PELO PROCESSO DE COPRECIPITA\u00c7\u00c3O, J. Eng. Exact Sci. 3 (2017) 1182\u20131191. doi:10.18540\/jcecvl3iss8pp1182-1191.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[10] Secretar\u00eda de Salud, NOM-127-SSA1-1994, Salud ambiental, agua para uso y consumo humano-L\u00edmites permisibles de calidad y tratamientos a que debe someterse el agua para su potabilizaci\u00f3n, D. Of. La Fed. (1994) 1\u20135. http:\/\/www.salud.gob.mx\/unidades\/cdi\/nom\/127ssa14.html.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[11] D. Mohan, C.U. Pittman, Arsenic removal from water\/wastewater using adsorbents\u2014A critical review, J. Hazard. Mater. 142 (2007) 1\u201353. doi:10.1016\/J.JHAZMAT.2007.01.006.<\/span><\/p>\n<p class=\"p6\" style=\"text-align: justify;\"><span style=\"font-size: 14px;\">[12] F.J. Hingston, A.M. Posner, J.P. Quirk, Competitive adsorption of negatively charged ligands on oxide surfaces, Discuss. Faraday Soc. 52 (1971) 334\u2013342. doi:10.1039\/DF9715200334<\/span><\/p>\n<p style=\"text-align: justify;\">\n<div id=\"fb-root\"><\/div>\r\n<script>(function(d, s, id) {\r\n  var js, fjs = d.getElementsByTagName(s)[0];\r\n  if (d.getElementById(id)) return;\r\n  js = d.createElement(s); js.id = id;\r\n  js.src = \"\/\/connect.facebook.net\/en_GB\/all.js#xfbml=1\";\r\n  fjs.parentNode.insertBefore(js, fjs);\r\n}(document, \"script\", \"facebook-jssdk\"));<\/script>\r\n <fb:comments href=\"http:\/\/www.journalnano.org\/?p=1613\" font=\"arial\" num_posts=\"5\" width=\"640\" height=\"600\" colorscheme=\"light\"  style=\"background:#F0F0F0;padding-top:0px;\r\npadding-right:0px;\r\npadding-bottom:0px;\r\npadding-left:0px;\r\nmargin-top:0px;\r\nmargin-right:0px;\r\nmargin-bottom:0px;\r\nmargin-left:0px;\r\n\"><\/fb:comments>","protected":false},"excerpt":{"rendered":"<p>This work evaluates the ability of nanoparticles (NPs) to remove arsenic (As+3) from water. <\/p>\n","protected":false},"author":1,"featured_media":1629,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[39],"tags":[],"_links":{"self":[{"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/posts\/1613"}],"collection":[{"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1613"}],"version-history":[{"count":6,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/posts\/1613\/revisions"}],"predecessor-version":[{"id":1633,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/posts\/1613\/revisions\/1633"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=\/wp\/v2\/media\/1629"}],"wp:attachment":[{"href":"http:\/\/www.journalnano.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1613"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1613"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.journalnano.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1613"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}