China
Africa
Explore chapters and articles related to this topic
Chemical Vapor Deposition (CVD) Technique for Nanomaterials Deposition
Published in Vidya Nand Singh, Chemical Methods for Processing Nanomaterials, 2021
Abhishek K. Arya, Rahul Parmar, K.S. Gour, Decio B. de F.N., R. Gunnella, J.M. Rosolen, V.N. Singh
The TMs display specific properties and transport different outputs with different reactants in surrounding elements, such as sulphides, oxides, selenides, nitrides, chalcogenides, and some MOFs having specific organic compounds, etc. The TMs are the elements that are placed in the d-block in the periodic table from IV to VII groups. TMs have variable oxidation states because of partially-filled d-orbit. The TMs have been used as nanoparticle materials at the nanoscale in electronic device applications, i.e., semiconductors devices, energy storage, and conversion devices i.e., Li+ and Na+ ion batteries, capacitors, supercapacitors, gas sensing devices, photovoltaics, etc.
Chemicals from Olefin Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
By way of clarification, the IUPAC definition defines a transition metal as (quote) an element whose atom has a partially filled d subshell, or which can give rise to cations with an incomplete d subshell (end quote). Most scientists describe a transition metal as any element in the d-block of the periodic table, which includes groups 3–12 on the periodic table. In actual practice, the f-block lanthanide and actinide series are also considered transition metals and are called inner transition metals. The word transition was first used to describe the elements now known as the d-block by the English chemist Charles Bury in 1921, who referred to a transition series of elements during the change of an inner layer of electrons from a stable group of 8 to1 of 18, or from 18 to 32.
Nanomedicine Clinical and Preclinical Use
Published in Bertrand Henri Rihn, Biomedical Application of Nanoparticles, 2017
Roudayna Diab, Sanghoon Kim, Ileana-Alexandra Pavel, Nadia Canilho, Fernanda Bianca Haffner, Sijin Li, Alain Celzard, Mihayl Varbanov, Emmanuel Lamouroux, Andreea Pasc
Metal-based NPs are mainly made of d-block elements of the periodic table. Elements of the block-p can be incorporated in the NPs lattice to form different types of compounds, such as metal oxide or metal sulfide. Since the surface-to-volume ratio is dramatically increased in NPs, the properties of nanosized materials will differ from the ones of bulk one (i.e., electronic, optic, magnetic, and catalytic properties; Mody et al., 2010). These properties are of particular interest for biomedical applications, such as imaging and hyperthermia therapy, as previously reviewed (Chen et al., 2016). NPs could be classified as a function of their physical properties used for biomedical applications: (1) plasmonic NPs, (2) magnetic NPs, and (3) quantum dots (QDs). Moreover, metal-based NPs are widely used as antibacterial agents.
Structural, elemental, and electrical conduction properties of corundum-type Mg2Co2Nb2O9
Published in Phase Transitions, 2023
Out of the various compositions, and solid solutions are suitable candidates for microwave communication applications [2–4] and the transition metal tantalates and niobates having , , , and , are known for their magnetoelectric (ME) response [5,6]. A transformation of microwave dielectrics to transition metal tantalates/niobates needs complete substitution of A-site cations by a d-block element. The composition is an intermediary mixed oxide solid solution and is a new member to the family.
A comprehensive review on synthesis, characterization and adsorption behavior of agricultural waste based adsorbents for heavy metals (Cr(VI) and Cd(II)) removal from wastewater
Published in Journal of Dispersion Science and Technology, 2023
Ritu Gupta, Sudhir Kumar Gupta, Chhagan Lal Gehlot
Chromium is an exciting transition metal of the d-block series, which occurs in nine different oxidation states(-2 to +6). Still, in an aqueous solution, Cr exists in highly recommended two oxidation states, i.e., trivalent and hexavalent forms.[9] Hexavalent Cr(VI) is 500 times highly noxious and more hazardous than trivalent Cr(III) because of its carcinogenic, mutagenic,[10] and high corrosion-resistive nature.It has been recognized as a top-priority pollutant by the US Environmental Protection Agency (EPA)[11] and the Chinese Environmental Protection Board (EPB).[12] In the environment, chromium is a widely accepted hard, brittle and gray material exhibiting corrosion resistance[13] and shows a high melting point. These properties make it very beneficial in stainless steel production (60%) by the steel industries. The industrial sources of chromium(II) originate from mining (metal finishing), steel, leather, electroplating, textile, dying, paint, and tanning industries. The maximum permissible limit for the discharge of Cr(VI) in drinking water is 0.05 mg/L (50 μg/L), while the total limit for discharge of Cr is 0.10 mg/L (100 μg/L) as the US EPA recommends.[14] Therefore, Cr(VI) contains hazardous wastewater that should be treated systematically before discharging into sewage or surface water and then efficiently eliminated from the water.[15]
Mosses as bioindicators of atmospheric deposition of Tl, Hg and As in Kosovo
Published in Chemistry and Ecology, 2023
Musaj Paçarizi, Trajče Stafilov, Robert Šajn, Krste Tašev, Flamur Sopaj
Thallium is placed in group 13 in the periodic table, and its common compounds are monovalent Tl+ trivalent and Tl3+ ones. The most toxic compounds of Tl are its monovalent forms, Tl2SO4, Tl2CO3, CH3COOTl [15–17]. Tl is widespread in the earth's crust but its participation in it is small; it reaches up to 2 mg/kg but its composition is usually under 1 mg/kg [18]. Thallium minerals are not frequent but it is often found in other minerals as traces [19]. Mercury is a d-block metal of group 12 in the periodic table, and it exists in liquid form in standard conditions. It is very rare in the earth's crust with a presence of 60 ppb [20]. Because of the high volatility of Hg and its compounds, it is emitted into the atmosphere easily from various ground surfaces, entering a dynamic cycle. Mercury, after being introduced into the atmosphere, undergoes chemical reactions and then is deposited again on the ground surfaces [21]. Mercury toxicity has been frequently reported [22, 23]. Arsenic is a group 15element, and unlike Tl and Hg, it is a metalloid (exhibiting properties of both metals and non-metals). It participates in the earth's crust with only 0.00005%, but its concentrations are variable and very much higher depending on the geology of the area [24]. Arsenic also is a very toxic element; its toxicity varies with its chemical forms such as oxidation state or if it is part of organic or inorganic compounds [25].