Lead Chromate Pigments and Türkiye

Turkchem 11 Dec 2023 41 4 dk okuma

TURKCHEM

Summary

The use of lead chromate pigments, represented by the PbCrO4 chemical formula, is banned in developed countries. However, their use has increased significantly in Turkey. These pigments are considered risky due to their components, which are environmental pollutants and carcinogens. Previously, European Union countries were the main suppliers of these pigments, but their supply has shifted to countries like India, Canada, and Colombia after the ban in the EU. This article examines the variation in annual imports and recommends using environmentally compatible organic pigments as an alternative.

Introduction

Lead chromate pigments, represented by the chemical formula PbCrO4, were first synthesized in 1809 by French chemist Louis N. Vauquelin (1). The first synthetic lead chromate pigment was commercially used in the 1920s. Due to its relatively high light and weather fastness, it became widely used in the United States, particularly in school buses and taxis for many years. In Turkey, lead chromate-based pigments are predominantly used for taxi yellows and road marking paints. However, lead chromate is a highly polluting component as it contains the heavy metal Cr, which is even more polluting and carcinogenic. Because of these properties, both the United States and the European Union have ceased the use of lead chromate pigments.

Lead Chromate Pigment Imports in Turkey

In 1993, when I started working in the paint industry, the first words I heard from pigment manufacturers during technical meetings were about the phasing out of lead chromate pigments. They suggested that these pigments should be replaced with organic pigments immediately. The annual imports of lead chromate pigments in Turkey, in terms of both US dollars and tons, have been compiled from Biruni TUIK's Foreign Trade Statistics database and are shown in Figure 1 (2). The value and volume of imported lead chromate pigments were around USD 1.5 million and 500 tons in the early 2000s. Since 2005, importation has increased rapidly and reached USD 9.2 million in 2013, as shown in Figure 1. The volume reached its peak level of 2,000 tons in 2013. Since 2015, imports have ranged from USD 6 to 7.6 million, with the volume varying between 1,650 and 1,850 tons annually. Until 2007, European Union countries led the import of lead chromate pigments in Turkey. However, their share decreased over time and eventually stopped completely in 2019. On the other hand, Canada's exports of lead chromate pigments to Turkey have been increasing since 2007, reaching their peak level in 2019. The main reason for this increase is the transfer of lead chromate production from CIBA to a Canadian company. However, Canada's exports have been declining in recent years, possibly due to financial reasons. As the production of lead chromate pigments slows down and stops in European Union countries, imports from India have been increasing since 2010, following a similar trend to Canada. Imports from India surpassed 760 tons in 2010 and peaked at 1,083 tons and USD 4.4 million in 2022. Colombia has also become a significant exporter of inorganic pigments to Turkey, as NUBIOLA's production shifted from Spain to Colombia after joining the FERRO company. The fourth largest country in Turkey's lead chromate imports is China. It has been determined that China's exports reached USD 870 thousand in 2020. [caption id="attachment_158450" align="aligncenter"] Figure 1. Annual importation values and volumes[/caption] During the first decade of the 2000s, Turkey imported lead chromate pigments from approximately 30 countries. However, the number of countries from which Turkey imports these pigments has now decreased to 6–7. The main exporting countries in terms of size are India, Canada, China, and Colombia. India is the primary source of lead chromate pigment imports, with 7 suppliers, while China has 2 suppliers, and Canada and Colombia each have 1. It is not appropriate that the use of lead chromate pigments in Turkey has increased to 1,800 tons, while developed countries have banned their use. In the early 2000s, the average usage of lead chromate pigments in Turkey was around 500 tons. The significant use of these pigments in road marking paints poses environmental risks. Each year, approximately 400–500 tons of lead chromate pigment is released into nature through dust emissions from road marking paints. However, the use of lead chromate pigment has largely been discontinued in Turkey, particularly in masterbatches used in yarn production and powder coatings. As mentioned earlier, lead chromate pigments are highly used in road marking paints, auto repair paints, industrial paints, and plastic masterbatch colorings. There may be some usage in the production of lower-quality construction paints. It is still unknown whether lead chromate pigments are used in toy coloring.

Lead Chromate Pigment Types and Organic Alternatives

Lead chromate pigments are PY 34 and PR 104 pigments with 2 Color Index and their contents are given in Table 1: • PY 34: Lead Chromate (Primrose, Lemon & Medium) PbCrO4 / PbSO4 • PR 104: Lead Chromate/Lead Molybdate: PbMoO4 [caption id="attachment_158451" align="aligncenter"] Table 1. Lead Chromate Types and their Chemical Contents[/caption]