Page 10 - EER-2-3

Explora: Environment
and Resource Environmental contamination of titanium

and regulatory ramifications. This work also seeks to until 1940 when the Kroll process was invented. Raw ores
31
fill important knowledge gaps regarding the dynamics, are reduced with petroleum-derived coke in a fluidized
ecotoxicity, and remediation of Ti materials, including bed reactor at 1,000°C. After the mixture is treated with
a critical assessment of the most recent experimental chlorine gas, TiCl is produced, which is then reduced by
4
and theoretical results. As noted above, there is limited liquid magnesium at 800 – 850°C. The resulting material
information available on the accumulation, fate, transport, is a porous sponge of Ti that is leached for purification,
and ecotoxicity of Ti in terrestrial and aquatic ecosystems, crushed, and melted in a consumable electrode vacuum arc
which is concerning given its increased use in a variety furnace. To increase uniformity, Ti is remelted to remove
of industries that have resulted in the release of Ti into inclusions. Other Ti extraction methods include Hunter’s
the environment. Similarly, there are few reviews on the sodium reduction of TiCl and the fused salt electrolysis of
remediation of Ti contamination in aquatic and terrestrial TiCl . 32 4
ecosystems, as well as a dearth of comprehensive 4
29
information on the specific pathways of Ti contamination, TiO is manufactured and used in various particle
2
environmental effects, and mitigating techniques. This sizes, as discussed earlier. TiO NPs are among the most
2
review seeks to: (i) Identify the sources of Ti inputs and used forms of the material, having a high refractive index
contamination in terrestrial and aquatic ecosystems; (ii) (n = 2.4) that makes them ideal in coating applications,
33
elucidate the dynamics and interactions of Ti in the soil– cosmetics, food, inks, medicine, plastics, and textiles. The
water–plant continuum; (iii) characterize the effects of NPs are also used in agriculture for enhancing the rate of
34
Ti accumulation in the environment on ecotoxicity; and photosynthesis, promoting plant growth, and controlling
35
(iv) discuss sustainable management strategies to reduce plant diseases, as well as for photocatalysts in water
the risks that Ti accumulation in terrestrial and aquatic treatment and air purification.
ecosystems presents. Such a wide application of Ti has stimulated increased
The following search terms were used in a mining and processing of Ti minerals. Based on the
Web of Science Core Collections literature search: USGS, 92% of the world’s consumption of TiO relies on
2
36
TS = (“Titanium”) AND TS = (“environment” OR “soil” ilmenite. Ti material production in China increased from
OR “aquatic” OR “terrestrial” OR “sediment” OR “river” 1.70 million metric tons in 2013 to 3.10 million metric
37
OR “lake” OR “marine” OR “ocean” OR “porous media”) tons in 2023. Australia has abundant ilmenite and rutile,
AND TS = (“contamination” OR “origin” OR “source” OR producing 790,000 metric tons of Ti minerals. Japan and
“distribution” OR “speciation” OR “biogeochemical” OR Russia have limited resources of Ti minerals but produce
“geochemical” OR “geochemistry” OR “biogeochemistry” 35,000 and 27,000 metric tons of Ti sponge, respectively
OR “remediation” OR “toxic” OR “toxicity” OR (Table S1). The global implications of Ti contamination,
“availability” OR “bioavailability” OR “management” particularly for regions with significant industrial or
OR “adsorption” OR “immobilization” OR “passivation” mining activities, have been discussed elsewhere. 38-40
OR “phytoremediation”). The VOSviewer program
(version 1.6.20; The Centre for Science and Technology 2.1. Ti contamination from geogenic origin
Studies (CWTS), Leiden University, The Netherlands) Ti minerals are generally known to be inert in soils and
was used to visualize the 5,819 results that were obtained resistant to weathering. As such, Ti concentrations in
from this search. This approach is intended to maximize soils are commonly used to assess the rate of weathering
under standing of the research landscape, highlight of parental minerals. In contrast to many primary and
existing knowledge gaps, and guide future studies in Ti secondary minerals, the weathering of Ti minerals does
biogeochemistry, environmental impacts, and remediation occur, albeit rather slowly. For example, neoformed
41
strategies. Figure S1 presents the number of published anatase or the slow weathering of bedrock are the sources
papers on Ti in soils and aquatic ecosystems, as well as of rutile, which is most prevalent in soils. In contrast,
42
a keyword co-occurrence map indicating the themes the weathering of Ti minerals occurs more quickly in
that have been studied most frequently in this field. This tropical soils. For example, 3.4% of Ti was found in soils
figure includes a comprehensive roadmap on the topic, from Australia, 15% in soils from Norfolk Island,
43
44
providing a visual representation of the progression and and 15% in soils from Hawaii. Due to extensive and
45
interconnected themes in Ti research. prolonged weathering, 2.3% Ti is present in Brazilian
soils. It has been reported that regarding Ti mobility
46
2. Sources of Ti contamination in an Amazonian ferralsol, weathering of Ti minerals
Although Ti was discovered in 1791 by the clergyman and proceeds as follows: Ilmenite, pseudorutile, rutile,
geologist William Gregor, it was not commercially used and anatase. The authors noted that the weathering
30
Volume 2 Issue 3 (2025) 4 doi: 10.36922/EER025130027