Seasonal lead release to drinking water and the effect of aluminum

Monitoring lead in drinking water is important for public health, but seasonality in lead concentrations can bias monitoring programs if it is not understood and accounted for. Here, we describe an apparent seasonal pattern in lead release to orthophosphate-treated drinking water, identified through point-of-use sampling at sites in Halifax, Canada, with various sources of lead. Using a generalized additive model, we extracted the seasonally-varying components of time series representing a suite of water quality parameters and we identified aluminum as a correlate of lead. To investigate aluminum’s role in lead release, we modeled the effect of variscite (AlPO4 · 2H2O) precipitation on lead solubility, and we evaluated the effects of aluminum, temperature, and orthophosphate concentration on lead release from new lead coupons. At environmentally relevant aluminum and orthophosphate concentrations, variscite precipitation increased predicted lead solubility by decreasing available orthophosphate. Increasing the aluminum concentration from 20–500 µg L-1 increased lead release from coupons by 41% and modified the effect of orthophosphate, rendering it less effective. We attributed this to a decrease in the concentration of soluble (<0.45 µm) phosphorus with increasing aluminum and an accompanying increase in particulate lead and phosphorus (>0.45 µm).

Assessment of Spatial Variability of Heavy Metals (Pb and Al) in Alluvial Soil around Delta State University of Science and Technology, Ozoro, Southern Nigeria

Soil heavy metals pollution is a major global threat, because of its impact to plants, animals, and the soil geotechnical properties. Geostatistical method was used to investigate the spatial distributions of aluminum and lead within a section of the Delta State University of Science and Technology, Ozoro, Nigeria. A total area of 1 km2 (100 hectares) was covered within the school environment. Twenty -five (25) topsoil samples were collected, at the end of the dry season (March 2021); when the water table in the study area was very low. The lead and aluminum concentrations of the 25 samples were measured by using the Association of Official Analytical Chemists (AOAC) approved methods. Using a geostatistical tool, the lead and aluminum concentrations and distribution in the soil were plotted on predication maps. The maps revealed irregular spatial distributions of lead and aluminum ions within the study area. The lead concentration was highest at the North-central region of the study area; while lead concentration was lowest at the Eastern region of the study area. In terms of the aluminum metal, the highest aluminum concentration was observed in the North eastern region; while aluminum concentration was lowest at the South western region. Data obtained from this study will be useful for agricultural and civil engineering purposes, mainly in the area of decision-making.

Study on valuable metal incorporation in the Fe–Al precipitate during neutralization of LIB leach solution

The role of aluminum concentration and pH in the purification of waste Li-ion battery leach solution was investigated using NaOH and LiOH as neutralization agents ([H2SO4] = 0.313 M, t = 6 h). Solution was prepared from synthetic chemicals to mimic real battery leach solution. Results demonstrate that pH (3.5–5.5) has a significant effect on the precipitation of metals (Fe, Al, Ni, Cu, Co, Mn, and Li), whereas higher temperature (T = 30 and 60 °C) decreases the precipitation pH of metals. Iron and aluminum were both found to precipitate at ca. pH 4 and the presence of aluminum in PLS clearly decreased the separation efficiency of Fe vs. active material metals (Ni, Co, Li). In the absence of dissolved aluminum, Fe precipitated already at pH 3.5 and did not result in the co-precipitation of other metals. Additionally, the Al-free slurry had a superior filtration performance. However, aluminum concentrations of 2 and 4 g/L were found to cause loss of Ni (2–10%), Co (1–2%) and Li (2–10%) to the Fe-Al hydroxide cake at pH 4. The use of LiOH (vs. NaOH) resulted in 50% lower co-precipitation of Ni, Co and Li. Overall, these results demonstrate that hydroxide precipitation can be an effective method to remove iron from battery waste leach solutions at aluminum concentrations of < 2 g/L only. Although the highest level of lithium loss in the cake was found at pH 4, the loss was shown to decrease with increasing pH.

Assessment of Coagulation–Flocculation Process Efficiency for the Natural Organic Matter Removal in Drinking Water Treatment

Natural organic matter (NOM) represents a range of heterogeneous hydrophobic and hydrophilic components naturally occurring in the water source and, due to the fact that they can act as precursors for the disinfection, by-products may have a considerable impact on drinking water quality. Coagulation–flocculation (C/F) is among the most applied processes for NOM removal from water sources (especially rivers). In this study, C/F efficiency for a river water supply was investigated in cold and warm conditions, by varying the coagulant dose and mixing conditions. In this study, polyhydroxy aluminum chloride PAX XL 60, and polyacrylamide FloPam AN 910 SEP were used as coagulant and flocculant, respectively. Multiple water quality indicators were determined, such as turbidity, chemical oxygen demand (COD), dissolved organic carbon (DOC), and residual aluminum concentration. Some unconventional parameters relevant for NOM removal were also considered, like absorbance at 254 nm (A254), at 280 nm (A280), and at 365 nm (A365), as well as the ratios A254/DOC, A254/280, and A254/A365. After coagulation–flocculation, turbidity was completely removed in all the studied conditions. The DOC content was reduced by up to 22.65% at a low temperature and by up to 31.81% at a high temperature. After the addition of polyelectrolyte in cold conditions, the efficiency in terms of A254 increased by up to 37.4%, while the specific absorbance decreased. The high molecular weight NOM increased after C/F, based on the A254/A365 ratio. Chemometric analysis was employed in order to determine the effect of the coagulant dose on the process efficiency. The optimum coagulation–flocculation conditions were corroborated by means of the principal component analysis.

Effect of mycosilvi and soil ameliorant to change aluminium concentration by Albizia chinensis in silica sand post mining soil medium

This study aimed to analyze the concentration change of Aluminum in the soil with addition of MycoSilvi and soil ameliorant in silica sand post mining soil media. There are three types of MycoSilvi, single or combination, added with soil ameliorant which tested on Albizia chinensis (Osbeck) Merrill. The experimental design used was a factorial design with two factors, MycoSilvi (M) consisting of four levels (M0 = without MycoSilvi; M1 = MycoSilvi type 1; M2 = MycoSilvi type 2; and M3 = MycoSilvi type 3) and soil Ameliorant (LC) consisting of four levels (L0C0 = without soil ameliorant; L1C0 = lime; L0C1 = compost; L1C1 = lime and compost). Data analysis used analysis of variance (ANOVA). The results showed that the combination of MycoSilvi and soil ameliorant decreased aluminum concentration from 7.70 to 0.10 cmol(+)/kg and increased pH from 3.20 to 5.67 were positively correlated with total biomass. Significant changes were shown in MycoSilvi type 3 with the addition of lime and compost (M3L1C1). Application of MycoSilvi type 3 (M3L0C0) gave equivalent response with application of lime (M0L1C0) to increased dry biomass, so that lime can be replaced with MycoSilvi type 3 (M3L0C0) to promote plant growth, especially biomass of plant.

Ytterbium impulse laser for surface modification of tool steel with B4C-Al powders

The paper deals with a new application solution of Ytterbium Picosecond Pulsed Fiber Laser for surface modification of 3Kh2V8F hot-work tool steel (the analog of AISI H21 steel). Surface modification was conducted by B4C-Al powders from preplaced pastes followed by laser heating. The ratio of B4C-Al powders was taken as 5/1 by weight and the paste thickness was approximately 1 mm. Laser treatment was conducted according to the following parameters: 1070 nm of wavelength, 100 W of power, 1 mJ of pulse energy, 100 ns pulse duration, pulse frequency range from 50 kHz to 90 kHz. Several tracks with different widths were obtained as a result of treatment depending on velocity of the laser move. EDS analysis showed that B4C particles were not completely dissolved in the weld beads. However, an enhanced concentration of boron (8-12 wt.%) was revealed in the vicinity of B4C particles. The aluminum concentration was low (up to 0.79 wt.%) on the surface of the weld beads.

BONE ALUMINUM AS A BIOLOGICAL MONITORING OF OCCUPATIONAL EXPOSURE TO ALUMINUM

ABSTRACTThe current proposed biological monitoring of aluminum is based on the analysis of aluminum concentration in blood/serum or in urine, but both considered to be reflective of short-term exposure. Based on its toxic kinetics, aluminum has been demonstrated to be accumulated in the bone. The aim of this study is to find out whether by analyzing bone aluminum, we might have an overview of aluminum accumulation that might cause health problems in the future. This review was conducted through a method of search and selection of articles from Pubmed, Cochrane Library, and Google Scholar databases aimed to answer question rising from the problem statement of this study. The process of searching articles used the keywords “occupational aluminum” OR “bone aluminum” AND “biological monitoring” OR “biomonitoring”. The selection of articles was performed using the defined inclusion and exclusion criteria. Initially, 61 articles were obtained, but after the selection process and hand searching, four articles remained consisting of two case reports and two cross sectional studies. Based on the selected evidence-based resources, bone can be a promising potential biomarker of aluminum, especially for cumulative exposure assessment. The use of in vivo neutron activation analysis (IVNAA) or X-ray fluorescence (XRF) technology for the purpose of noninvasively quantifying aluminum concentration in the bone, is suitable enough to be performed in occupational settings. Keywords: Bone aluminum, occupational exposure, IVNAA, XRF, biomonitoring, biological monitoring

Impact of Surface States and Aluminum Mole Fraction on Surface Potential and 2DEG in AlGaN/GaN HEMTs

The presence of surface traps is an important phenomenon in AlGaN/GaN HEMT. The electrical and physical properties of these surface traps have been analyzed through the study of 2DEG electron concentration along with the variation of aluminum percentage in the barrier layer of HEMT. This analysis shows that from deep to shallow donors, the percentage change in electron density in 2DEG gets saturated (near 8%) with change in aluminum concentration. The depth of the quantum potential well below the Fermi level is also analyzed and is found to get saturated (near 2%) with aluminum percentage when surface donor states energy changes to deep from shallow. The physics behind this collective effect is also analyzed through band diagram too. The effect of surface donor traps on the surface potential also has been discussed in detail. These surface states are modeled as donor states. Deep donor (EC − ED = 1.4 eV) to shallow donor (EC − ED = 0.2 eV) surface traps are thoroughly studied for the donor concentration of 1011 to 1016 cm−2. This study involves an aluminum concentration variation from 5 to 50%. This paper for the first time presents the comprehensive TCAD study of surface donor and analysis of electron concentration in the channel and 2DEG formation at AlGaN–GaN interface.