Alkaline refining of crude lead: a method of arsenic removal and the behavior of arsenic in the process

In this work, the alkaline refining of arsenic in crude lead was studied with a mixture of sodium hydroxide and sodium carbonate as alkaline refining agents. Taking the arsenic removal rate as the research object, the effects of reaction temperature, holding time, Na2CO3:NaOH, the dosage of refining agent were investigated. The arsenic removal rate is 79.09% under the optimum experimental conditions as follows: reaction temperature 823 K, holding time 60 min, Na2CO3:NaOH 1:4, refining agent dosage 10%. The oxidation purification mechanism of arsenic was studied by XPS, SEM-EDS, XRD and FT-IR. The results show that arsenic in the crude lead is gradually oxidized by oxygen and lead oxide during arsenic removal process, and the arsenic trioxide is eventually converted into sodium arsenate (Na3AsO4) and lead arsenate (Pb2As2O7) in the slag.

The Technology Transfer from Europe to China in the 17th–18th Centuries: Non-Invasive On-Site XRF and Raman Analyses of Chinese Qing Dynasty Enameled Masterpieces Made Using European Ingredients/Recipes

Two masterpieces of the Qing Dynasty (1644–1912 CE), one in gilded brass (incense burner) decorated with cloisonné enamels stylistically attributed to the end of the Kangxi Emperor’s reign, the other in gold (ewer offered by Napoleon III to the Empress as a birthday present), decorated with both cloisonné and painted enamels bearing the mark of the Qianlong Emperor, were non-invasively studied by optical microscopy, Raman microspectroscopy and X-ray microfluorescence spectroscopy (point measurements and mapping) implemented on-site with mobile instruments. The elemental compositions of the metal substrates and enamels are compared. XRF point measurements and mappings support the identification of the coloring phases and elements obtained by Raman microspectroscopy. Attention was paid to the white (opacifier), blue, yellow, green, and red areas. The demonstration of arsenic-based phases (e.g., lead arsenate apatite) in the blue areas of the ewer, free of manganese, proves the use of cobalt imported from Europe. The high level of potassium confirms the use of smalt as the cobalt source. On the other hand, the significant manganese level indicates the use of Asian cobalt ores for the enamels of the incense burner. The very limited use of the lead pyrochlore pigment (European Naples yellow recipes) in the yellow and soft green cloisonné enamels of the Kangxi incense burner, as well as the use of traditional Chinese recipes for other colors (white, turquoise, dark green, red), reinforces the pioneering character of this object in technical terms at the 17th–18th century turn. The low level of lead in the cloisonné enamels of the incense burner may also be related to the use of European recipes. On the contrary, the Qianlong ewer displays all the enameling techniques imported from Europe to obtain a painted decoration of exceptional quality with the use of complex lead pyrochlore pigments, with or without addition of zinc, as well as cassiterite opacifier.

From arsenic to DDT: Pesticides, Fascism and the invisibility of toxic risks in the early years of Francoist Spain (1939-1953)

This paper reviews the way in which Spanish agriculture climbed onto the pesticide treadmill. We claim that Fascist policies and expert advice assembled in the early 1940s accelerated the introduction of pesticides into Spanish agriculture and promoted the emergence of the Spanish pesticide industry in the times of autarky. Agricultural engineers were the key protagonists in this process, but other human and non-human actors also played a pivotal role: a new pest (the Colorado beetle), Francoist politicians, farmers, landowners and industry managers. Our focus is on the use of pesticides against the Colorado beetle (the main threat to the potato crop), and the transition from arsenical pesticides to DDT during the 1940s. We discuss how the politics of autarky offered new opportunities for developing agronomic programmes and the chemical industry and led to the creation of the Register of Pesticides in 1942. We also discuss the role of these regulations in concealing the risks of pesticides from farmers and food consumers. Arsenic pesticides became sources of slow poisoning and tools for social control while reinforcing the alliance of agricultural engineers and Fascist politicians in their autarkic and authoritarian projects. When DDT arrived in Spain, the agricultural engineers praised the low toxicity it had demonstrated (compared to lead arsenate) in its first uses in public health and in military campaigns in Italy. Indeed, the data concerning its potential dangers disappeared from view thanks in part to a large multimedia campaign launched to promote the introduction of the new organic pesticides in Spanish agriculture, which is described at the end of the paper.

Investigation of the Pigments and Glassy Matrix of Painted Enamelled Qing Dynasty Chinese Porcelains by Noninvasive On-Site Raman Microspectrometry

A selection of 15 Chinese painted enameled porcelains from the 18th century (Qing dynasty) was analyzed on-site by mobile Raman and XRF microspectroscopy. The highly prized artifacts are present in the collections of the Musée du Louvre in Paris and Musée Chinois at Fontainebleau Castle in France. In the painted enamels, pigments such as Naples yellow lead pyrochlore, hematite, manganese oxide and carbon and opacifiers such as lead arsenates were detected. The glassy matrices of the enamels mainly belonged to lead-rich and lead-alkali glass types according to the Raman spectra obtained. The glaze and body phases of the porcelain artifacts were also analyzed. The detection of lead arsenate apatite in some of the blue enamels was significant, indicating the use of arsenic-rich European cobalt ores (smalt) and possibly mixing with Asian cobalt. This characteristic phase has also been identified in French soft-paste porcelains and glass decor and high-quality Limoges enamels from the same period. Based on the shape of the Raman scattering background, the presence of colloidal gold (Au° nanoparticles) was identified in red, orange and pink enamels. Different types of Naples yellow pigments were also detected with Sb-rich, Sn-rich and mixed Sb–Sn–(Zn, Fe?) compositions in the yellow enamels. The results were compared to previous data obtained on Chinese cloisonné and painted enameled metalware and Limoges enamels as well as French enameled watches.

Structural Assessment of Fluorine, Chlorine, Bromine, Iodine, and Hydroxide Substitutions in Lead Arsenate Apatites (Mimetites)–Pb5(AsO4)3X

Five lead-arsenate apatites (mimetites)-Pb5(AsO4)3X—where X denotes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and hydroxide (OH)—were synthesized via precipitation from aqueous solutions. The crystal structures were determined through Rietveld refinement of powder synchrotron X-ray data. All the compounds crystallized in the hexagonal class symmetry (space group P63/m). The Rietveld refinement indicated that mimetite-Cl, -Br, -I, and -OH had an anion deficiency at position X. Substitution of halogens in a mimetite structure brought about systematic changes in unit-cell parameters, interatomic distances, and metaprism twist angles φ, proportional to the substituted halogen’s ionic radius. Mimetite-OH did not follow the linear correlations determined within the series. Twist angle φ, a useful device for monitoring changes in apatite topology, ranged from 20.34° for mimetite-F to 11.42° for mimetite-I. The geometric method has been proposed for determining the diameter of hexagonal channels hosting halogens in apatites. A comparison of the results with halogenated pyromorphites showed similar systematic trends: the substitutions in mimetites have comparable effect on the interatomic distances as in their phosphorous analogues.

Relationship of Arsenic and Lead in Soil with Fruit and Leaves of Apple Trees at Selected Orchards in Michigan

ABSTRACT Historically, lead arsenate pesticides were commonly used in fruit orchards. Residues of metals from this historical use can persist in soil for decades, which can result in potential risk for humans if they consume fruits grown on contaminated soil. This research was conducted to assess lead and arsenic levels in apples, leaves, and orchard soil where the apples were grown to determine the relationship between metal levels in fruits and fruit products with those in orchard soil. Soil and tree tissue samples were collected from several Michigan farms, and metal concentrations were quantified by using microwave extraction and inductively coupled plasma mass spectrometry. Soil samples were collected at depths of 0 to 20 cm and 20 to 40 cm at a distance of 1 m from the tree trunk. Fruit samples also were processed into juice and pomace fractions to assess the partitioning of arsenic and lead during juice processing. The lead concentration was significantly higher in topsoil (9.4 μg/kg) compared with subsoil (6.9 μg/kg), but the arsenic content did not differ between the two soil layers (P > 0.05). Lead concentrations in apple leaves were correlated with lead in topsoil (0 to 20 cm; P = 0.03). Concentrations of total arsenic in all juice samples were less than 1 μg/kg and showed less potential than lead for uptake and translocation to fruits. There was no significant relationship between soil arsenic content and total arsenic concentrations in juice, pomace, and leaf samples (P > 0.05). Results of this research indicate that lead and total arsenic concentrations in apples and apple products from these selected orchards in Michigan are unlikely to be impacted by the contamination of these metals in orchard soil. HIGHLIGHTS

Non-Invasive On-Site Raman Study of Pigments and Glassy Matrix of 17th–18th Century Painted Enamelled Chinese Metal Wares: Comparison with French Enamelling Technology

A selection of 10 Chinese enamelled metal wares dating from the 17th–18th centuries (Qing Dynasty) was analysed on-site by mobile Raman microspectroscopy. These wares display cloisonné and/or painted enamels and belong to the collections of Musée du Louvre in Paris and Musée Chinois at the Fontainebleau Castle in France. Pigments (Naples yellow lead pyrochlore, hematite, manganese oxide etc.), opacifiers (fluorite, lead arsenates) and corresponding lead-based glassy matrices were identified. One artefact was also analysed by portable X-ray fluorescence spectrometry (pXRF) in order to confirm the Raman data. In some of these metal wares, it is suggested that cassiterite was unpredictably used as an opacifier in some parts of the decor. The results are compared to previous data obtained on Chinese cloisonné and Limoges enamels as well as recent data recorded on painted enamelled porcelains of the Qing Dynasty. Lead arsenate apatite detected in some of the 17th–18th century blue enamelled decors is related to the use of arsenic-rich European cobalt ores, as also characterized in French soft-paste porcelain and glass decors and high-quality Limoges enamels for the same period. However, lead arsenate could then also have been deliberately used for white opacification. The specific Raman signature displaying the shape of the Raman scattering background indicates the presence of colloidal gold (Au° nanoparticles) in red to violet enamelled and cloisonné areas. At least three types of Naples yellow lead pyrochlore pigments identified with Sb-rich, Sn-rich and mixed Sb–Sn–(Zn, Fe?) compositions prove the use of European pigments/recipes.