Flow Rate and Interference Studies for Copper Binding to a Silica-Immobilized Humin Polymer Matrix: Column and Batch Experiments

Batch and column experiments were performed to determine the Cu(II) binding capacity of silica-immobilized humin biomass. For column studies, 500 bed volumes of a 0.1 mM Cu(II) solution were passed through humin packed columns at the flow rates of 1, 1.5, 2, and 3 mL/min. The biopolymer showed an average Cu binding capacity of 12 ± 1.5 mg/g and a Cu recovery of about 96.5 % ± 1.5. The breakthrough points for Cu(II) alone were approximately 420, 390, 385, and 300 bed volumes for the flow rates of 1, 1.5, 2 and 3 mL/min, respectively. The interference studies demonstrated that at low concentrations, the hard cations Ca(II) and Mg(II) did not seem to represent a major interference on Cu(II) binding to the humin biopolymer. The selectivity showed by this biopolymer was Cu(II)>Ca(II)>Mg(II). On the other hand, batch experiments showed that Ca(II) + Mg(II) at 100mM each reduced the Cu(II) binding to 73 %. However, 1000 mM concentrations of Ca(II) and Mg(II), separately and in mixture, reduced the Cu(II) binding to 47 %, 44 % and 31 %, respectively. The results of this study showed that immobilized humin in a silica matrix could represent an inexpensive bio-source for Cu removal from contaminated water, even in the presence of low concentrations of the hard cations Ca(II) and Mg(II)

Sorption kinetic study of selenite and selenate onto a high and low pressure aged iron oxide nanomaterial

The sorption of selenite (SeO32−) and selenate (SeO42−) onto Fe3O4 nanomaterials produced by non microwave-assisted or microwave-assisted synthetic techniques was investigated through use of the batch technique. The phase of both synthetic nanomaterials was determined to be magnetite by X-ray diffraction. The average grain sizes of non microwave-assisted and microwave-assisted synthetic Fe3O4 were determined to be 27 and 25 nm, respectively through use of the Scherrer\u27s equation. Sorption of selenite was pH independent in the pH range of 2-6, while sorption of selenate decreased at pH 5 and 6. The addition of Cl− had no significant effect on selenite or selenate binding, while the addition of NO3− only affected selenate binding to the microwave assisted Fe3O4. A decrease of selenate binding to both synthetic particles was observed after the addition of SO42− while selenite binding was not affected. The addition of PO43− beginning at concentrations of 0.1 ppm had the most prominent effect on the binding of both selenite and selenate. The capacities of binding, determined through the use of Langmuir isotherm, were found to be 1923 and 1428 mg Se/kg of non microwave-assisted Fe3O4 and 2380 and 2369 mg Se/kg of microwave-assisted Fe3O4 for selenite and selenate, respectively

Arsenic in drinking water in the Los Altos de Jalisco region of Mexico Arsénico en el agua potable de la región de Los Altos de Jalisco, México

OBJECTIVE: To establish the degree of contamination by arsenic in drinking water in the Los Altos de Jalisco (LAJ) region of west-central Mexico, and to estimate the levels of exposure that residents of the area face. METHODS: Total arsenic concentration (the sum of all arsenic forms, organic and inorganic) was determined for 129 public water wells in 17 municipal capitals (cabeceras municipales) of the LAJ region, using inductively coupled plasma-optical emission spectroscopy. For most of the wells, water samples were taken in both November 2002 and October 2003. The levels of exposure to arsenic were estimated for babies (10 kg), children (20 kg), and adults (70 kg). RESULTS: Mean concentrations of arsenic higher than the Mexican national guideline value of 25 µg/L were found in 44 (34%) of the 129 wells. The mean concentration of total arsenic for the 129 wells ranged from 14.7 µg/L to 101.9 µg/L. The highest concentrations were found in well water samples collected in the cities of Mexticacán (262.9 µg/L), Teocaltiche (157.7 µg/L), and San Juan de los Lagos (113.8 µg/L). Considering the global mean concentration for all the wells in each of the 17 cities, the mean concentration of arsenic exceeded the Mexican guideline value in 7 of the cities. However, the global mean concentration in all 17 cities was higher than the World Health Organization guideline value of 10 µg/L for arsenic. The range of the estimated exposure doses to arsenic in drinking water was 1.1-7.6 µg/kg/d for babies, 0.7-5.1 µg/kg/d for children, and 0.4-2.7 µg/kg/d for adults. CONCLUSIONS: At the exposure doses estimated in the LAJ region, the potential health effects from chronic arsenic ingestion include skin diseases, gastrointestinal effects, neurological damage, cardiovascular problems, and hematological effects. While all the residents may not be affected, an important fraction of the total population of the LAJ region is under potential health risk due to the ingestion of high levels of arsenic. Epidemiological studies to determine the arsenic levels in the blood, hair, and nails of humans should be conducted in the LAJ region to help assess the relationship between the prevalence of health problems and the chronic ingestion of arsenic.OBJETIVOS: Determinar el grado de contaminación con arsénico del agua potable en la región de Los Altos de Jalisco (LAJ), en la parte centrooccidental de México, y estimar el nivel de exposición que enfrentan los habitantes de esa zona. MÉTODOS: Se determinó la concentración total de arsénico (la suma de todas las formas de arsénico, tanto orgánicas como inorgánicas) en 129 pozos de agua públicos en 17 cabeceras municipales de LAJ, mediante espectroscopia de emisión óptica con plasma inductivamente acoplado. En la mayoría de los pozos se tomaron muestras en noviembre de 2002 y en octubre de 2003. En los restantes se tomó la muestra en uno de esos dos momentos. El nivel de exposición al arsénico se estimó para lactantes (10 kg), niños (20 kg) y adultos (70 kg). RESULTADOS: En 44 (34%) de los 129 pozos se encontraron concentraciones media de arsénico superiores al límite de 25 µg/L, establecido en la norma nacional mexicana. Las concentraciones media de arsénico total en los 129 pozos estuvieron entre 14,7 µg/L y 101,9 µg/L. Las mayores concentraciones se encontraron en las muestras de agua colectadas en los pozos de Mexticacán (262,9 µg/L), Teocaltiche (157,7 µg/L) y San Juan de los Lagos (113,8 µg/L). Si se toma en cuenta la concentración general de todos los pozos de cada una de las 17 ciudades, la concentración media de arsénico fue superior a lo establecido en la norma mexicana en 7 ciudades. La concentración media general en las 17 ciudades fue superior al valor de 10 µg/L establecido en los lineamientos de la Organización Mundial de la Salud. Los niveles estimados de las dosis de exposición al arsénico por el agua potable fue de 1,1-7,6 µg/kg/d en los lactantes, de 0,7-5,1 µg/kg/d en los niños y de 0,4-2,7 µg/kg/d en los adultos. CONCLUSIONES: Según la dosis de exposición estimada en la región de LAJ, la ingestión continuada de arsénico puede afectar a la salud y causar enfermedades de la piel, trastornos gastrointestinales, daños neurológicos, problemas cardiovasculares y afecciones hematológicas. Aunque esta situación no afecte a todos los habitantes, la salud de una gran parte de la población de LAJ puede encontrarse en riesgo debido a la ingestión de cantidades elevadas de arsénico. Se deben realizar estudios epidemiológicos para determinar el contenido de arsénico en la sangre, el pelo y las uñas de las personas que viven en la región de LAJ, a fin de ayudar a evaluar la relación entre la prevalencia de problemas de salud y la ingestión continuada de arsénico

Removal of copper, lead, and zinc from contaminated water by saltbush biomass: Analysis of the optimum binding, stripping, and binding mechanism

Experiments performed on the Cu(II), Pb(II), and Zn(II) binding by saltbush biomass (Atriplex canescens) showed that the metal binding increased as pH increased from 2.0 to 5.0. The highest amounts of Cu, Pb, and Zn bound by the native biomass varied from 48-89%, 89-94%, and 65-73%, respectively. The hydrolyzed biomass bound similar amount of Pb and 50% more Cu and Zn than the native. The esterified biomass had a lower binding capacity than native; however, esterified flowers bound 45% more Cu at pH 2.0 than native flowers. The optimum binding time was 10 min or less. More than 60% of the bound Cu was recovered using 0.1 mM HCl, while more than 90% of Pb was recovered with either HCl or sodium citrate at 0.1 mM. For Zn, 0.1 mM sodium citrate allowed the recovery of 75%. Results indicated that carboxyl groups participate in the Cu, Pb, and Zn binding. © 2007

Advanced Analytical Techniques for the Measurement of Nanomaterials in Food and Agricultural Samples

Nanotechnology offers substantial prospects for the development of state-of-the-art products and applications for agriculture, water treatment, and food industry. Profuse use of nanoproducts will bring potential benefits to farmers, the food industry, and consumers, equally. However, after end-user applications, these products and residues will find their way into the environment. Therefore, discharged nanomaterials (NMs) need to be identified and quantified to determine their ecotoxicity and the levels of exposure. Detection and characterization of NMs and their residues in the environment, particularly in food and agricultural products, have been limited, as no single technique or method is suitable to identify and quantify NMs. In this review, we have discussed the available literature concerning detection, characterization, and measurement techniques for NMs in food and agricultural matrices, which include chromatography, flow field fractionation, electron microscopy, light scattering, and autofluorescence techniques, among others

Effects of lead, EDTA, and IAA on nutrient uptake by alfalfa plants

The element concentrations of alfalfa plants exposed for 10 d to 40 mg lead (Pb) L- 1 from lead nitrate [Pb(NO3)2] alone, or combined with ethylenediaminetetraacetic acid (EDTA) and indole-3-acetic acid (IAA), was determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Indole-3-acetic acid at 10 μM and Pb/EDTA/IAA at 10 μM increased potassium (K) concentration in roots by 87% and 94%, respectively (P \u3c 0.05). However, IAA at 100 μM decreased K concentration in leaves (P \u3c 0.05). Plants exposed to 100 μM IAA, Pb/IAA at 100 μM, and Pb/EDTA/IAA at 100 μM had, respectively, 30%, 55%, and 40% more sulfur (S) in leaves than control plants (P \u3c 0.05). Lead and Pb/IAA reduced Ca concentration in stems and leaves (P \u3c 0.05). Conversely, Pb and Pb/EDTA increased Cu concentration in roots and stems. IAA at 100 μM, Pb, and Pb/EDTA/IAA decreased Zn concentration in roots (P \u3c 0.05). Manganese (Mn) and molybdenum (Mo) concentration in roots and stems was lower in plants treated with Pb and Pb/IAA (P \u3c 0.05). Pb and Pb/IAA reduced (P \u3c 0.05) the iron (Fe) concentration in roots. However, the addition of EDTA and IAA at 10 μM reduced the negative effects of Pb on Fe absorption. Copyright © Taylor & Francis Group, LLC

Interaction of nanoparticles with edible plants and their possible implications in the food chain

The uptake, bioaccumulation, biotransformation, and risks of nanomaterials (NMs) for food crops are still not well understood. Very few NMs and plant species have been studied, mainly at the very early growth stages of the plants. Most of the studies, except one with multiwalled carbon nanotubes performed on the model plant Arabidopsis thaliana and another with ZnO nanoparticles (NPs) on ryegrass, reported the effect of NMs on seed germination or 15-day-old seedlings. Very few references describe the biotransformation of NMs in food crops, and the possible transmission of the NMs to the next generation of plants exposed to NMs is unknown. The possible biomagnification of NPs in the food chain is also unknown. © 2011 American Chemical Society