Need of Gallium Recovery from Waste Samples: A Review

Monika Swami^1*, Kinjal Patel²

^1*Department of Chemical Engineering, SAL College of Engineering, Ahmadabad, 380060, India

²Department of Chemical Engineering, SAL Engineering and Technical Institute, Ahmadabad, 380060, India

*Corresponding Author Email: monika.swami@sal.edu.in

[Received: 19 February 2021; Revised: 13 April 2021; Accepted: 21 May 2021]

Abstract: Gallium is an vital rare metal mainly because of its growing demand in different domain of life. It has wide applications. Gallium is considered as the backbone of the electronics industry. The supply and demand of gallium-bearing products has gradually increased during the past decade. Therefore, from the environmental stand point the need for sensitive and reliable methods for determining trace concentrations of gallium has become apparent in various fields. Gallium has become increasingly popular as a substrate material for electronic devices. Aside from ore, gallium can be obtained from such industrial sources as the Bayer process caustic liquor that is a byproduct of bauxite processing, flue dust removed from the fume-collection system in plants that produce aluminum by the electrolytic process, zinc refinery residues, gallium scrap materials, and coal fly ash. The purification process for gallium can start with solvent-extraction processes where the concentrations of impurities, especially metals, are reduced to the ppm range. The main aim of this  paper is  to simply put up  the salient facts regarding gallium  and identify applicable sources of information thereby one may create a suitable environment for the development of methods for the production of gallium via leaching through various waste samples.

Key words: Gallium, Electronic Industry, coal fly ash

Introduction

Gallium was first isolated by Lecoq de Boisbaudran in France in1875. The name is believed to derive from ‘Gallia’ or from ‘Gallus’ (Latin for the French ‘coq’ or cockerel). Commercial recovery of gallium first occurred in 1943 in the USA.

Occurrence and relative abundance

Gallium is found in variety of minerals aluminium and zinc with very low concentrations. When these minerals are processed to recover the major metals present, the Gallium tends to become more concentrated, and thus economic to extract. Gallium is commonly associated in nature with aluminium, zinc and germanium. It is primarily recovered from aluminium and zinc ores, coal. Gallium is usually present in the range of 5-200ppm range in most minerals.

Table1. Gallium content in different minerals

Hence, the industrial extraction of gallium is an important investigation topic. There is a necessity of pure gallium in large amounts[W.F. Hillebrand].

Gallium is a relatively common metallic element that is chemically similar to aluminium, although it is nearly as dense as iron in its pure form. High-purity gallium powder turns into a liquid above about 27°C. It is found as a by-product of alumina production where gallium is extracted, in an impure form, from the caustic liquor that is generated during bauxite processing. This form is then further refined to high purity (>99.9999%) gallium, also known as 6N Gallium. Gallium is also recovered from the by-products of zinc refining (chiefly by Dowa Mining in Japan, and possibly some Chinese producers). Gallium is mainly used either as an arsenide (GaAs) or nitride (GaN). Together, these compounds account for about 98% of gallium consumption worldwide. In addition to being a semi-conductor, gallium arsenide converts electricity into light, and is therefore a key component of light emitting diodes (LEDs).

End Users of Gallium

Gallium is electronic metal. About 98% of Gallium metal is being used as Gallium Arsenide, Gallium Phosphide and Gallium Gadolinium Garnet (GGG) Wafer products. Electron mobility and activation energy of its inter-metallic compounds in Gallium are found to be better than Germanium and Silicon. Gallium has promising future application in low melting alloys for electrical contacts especially in solar cells where it has an edge over its Silicon counterpart as it maintains the conversion efficiency at higher temperatures.  Gallium is also used in Solar Neutrino Research. The electronic /opto - electronic industry used Gallium and its compounds like Arsenide (GaAs) and Gallium Phosphide (GaP), mostly as semiconductor materials. These semiconductors find application, as raw material, in the  manufacture of a large variety of electronic products. A list of such products is presented below :

• Semi Conductors

• Laser Diodes

• Light Emitting Diodes (LED s)

• Photo Detectors

• Analogue and Digital ICs

• High performance photo-voltaic cells

• Computer Memory devices

• Superconductors and Super Conducting Magnets

• Optoelectronics

• Magnetic Bubble Memories etc.

A Gallium Arsenide chip has significances like: it can work five times faster than silicon, it uses less power, it is less affected by radiation and it can convert electronic signals to light. GaAs and silicon may be combine in a single chip by placing a layer of Gallium and Arsenic atoms on a silicon base. Tilting the silicon base by four degrees creates atomic steps on which Gallium and Arsenic atoms can nestle comfortably. Hybrid chips may soon find wide applications in solar cells and charge-coupled devices (which turn light into electronic signals). Silicon crystals are physically much easier to grow than GaAs crystals and much cheaper to produce. In 2000, GaAs chips cost 25% to 40% more than comparable silicon devices. Advances in processing technology and larger GaAs wafer diameters are urgently needed to bring down the price of GaAs components. It is therefore referred to as the backbone of electronic industry [R.R. Moskalyk]

Application of Gallium

Electronic and Electromotive:  Gallium nitride (GaN) and gallium arsenide (GaAs) are semiconductors and appear in compounds used in light-emitting diodes (LEDs). Gallium nitride (GaN) emits blue light in LEDs and is a key component in blue laser devices that have become very popular. Other applications include transistors, the manufacture of ultra-high speed logic chips, and for low-noise microwave preamplifiers. It has been suggested that a liquid gallium-tin alloy could be used to cool computer chips in place of water. The GaAs and GaN used in electronic components, representing about 98% of the gallium consumption in the US.

Energy: Gallium is one of the promising photovoltaic compounds - copper indium gallium selenium sulfide or CIGS, used to produce thin film solar panels, as an efficient alternative to crystalline silicon.

Hydrogen fuel cell: Aluminum-gallium alloy can potentially provide a solid hydrogen source for transportation purposes, effectively a hydrogen fuel cell. 

Science and Medicine: Gallium is used in metal-in-glass high-temperature thermometers. A low temperature liquid eutectic alloy of gallium, indium, and tin, is widely available in medical thermometers (fever thermometers)[5]. Gallium citrate and gallium nitrate are used as radiopharmaceutical agents in a nuclear medicine imaging procedure commonly referred to as a gallium scan. Gallium-68 has been used as an experimental positron emitting gallium isotope, in a PET scan technique which combines features of the gallium scan and the CT/PET scan.

Gallium nitrate is also used as an intravenous pharmaceutical to treat hypercalcemia associated with tumor metastasis to bones and gallium maltolate is used in clinical and preclinical trials as a potential treatment for cancer, infectious disease, and inflammatory diseases.  Research is being conducted to determine whether gallium can be used to fight bacterial infections in people with cystic fibrosis. Some research is being devoted to gallium alloys as substitutes for mercury dental amalgam, but these compounds have yet to see wide acceptance [D.L. Smith et.al]

Industrial Products: Gallium is used to create brilliant mirrors as gallium wets glass or porcelain.  It readily alloys with most metals, and has been used as a component in low-melting temperature alloys and added in quantities up to 2% in common solders can aid their wetting and flow characteristics.

                                                      Fig. 1. End use of Gallium

Indian Scenario

Currently M/s Hindustan Aluminium Company Ltd (HINDALCO) produces around 40-45 kg/annum of Gallium Metal (3N grade, 99.9% purity) in India by the use of Mercury Amalgamation Technology of BARC, Mumbai. The other Gallium Plant (with around 30kg/annum capacity, 3N grade) at Madras Aluminium Company Ltd. (MALCO) is presently not in operation. The same Mercury Amalgamation Technology was used but this was provided by Central Electrochemical Research Institute, Karaikudi, Tamilnadu.

Domestic requirement of Gallium was projected to be around 600 kg per annum in 1997 keeping in view the requirements for the Gallium Arsenide Technology (GATEC) Project for production of Gallium Arsenide Semi-conductor Devices. Research Institutes like Centre for Materials for Electronics Technology (CMET), Hyderabad; BARC, Mumbai; Anna University, Chennai; NFC, Hyderabad and a few others are also presently engaged in the purification of Gallium metal from 3N to 5N/ or 6N/7N Grade for meeting to the requirements of high end research.

Hence, the industrial extraction of gallium is an important investigation topic.

Domestic Production and Use

No domestic primary gallium recovery was reported in 2010. One company in Utah recovered and refined gallium from scrap and impure gallium metal, and one company in Oklahoma refined gallium from impure metal. Imports of gallium, which supplied most of U.S. gallium consumption, were valued at about $35 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about 99% of domestic gallium consumption. About 64% of the gallium consumed was used in integrated circuits (ICs). Optoelectronic devices, which include laser diodes, light-emitting diodes (LEDs), photodetectors, and solar cells, represented 35% of gallium demand. The remaining 1% was used in research and development, specialty alloys, and other applications. Optoelectronic devices were used in areas such as aerospace, consumer goods, industrial equipment, medical equipment, and telecommunications. ICs were used in defense applications, high-performance computers, and telecommunications.

Gallium Market Survey

The global Gallium Nitride (GaN) semiconductor devices market size was valued at USD 974.9 million in 2016. The market is expected to experience significant growth over the next eight years, owing to the accelerating demand for power electronics that consume less power and are energy efficient. GaN-based semiconductors possess dynamic electrical and chemical properties, such as high-voltage breakdown and saturation velocity that make them the appropriate choice for use in a variety of switching devices [ D.A. Kamer].

Manufacturers are emphasizing on improving the GaN technology and most of the technological advancements were made during 2010 to 2016. In 2010, the first Gallium Nitride power device was released by International Rectifier. In 2012, the first 6 inchGaN-on-Si Epiwafers were introduced in the market. The prominent industry players are engaged in undertaking collaborations and strategic partnerships for developing and improving the GaN technology [M.Frenzel et.al].

The gallium market has continued to experience pressure due to increased demand from LED manufacturers since the beginning of 2011. Some producers have seen demand for LED applications double since the same time last year. Many are speculating that increased demand for CIGS photovoltaic cells, following concerns about nuclear energy arising from the situation in Japan, will push gallium prices well above $1000/kg by the mid-point of 2011. There may still be room for gallium to go higher; however, many producers in China already have plans in place to significantly expand production capacity by the start of 2012. According to some calculations, if all the new capacity is completed on time, Chinese gallium production could double to over 100MT in 2012. Even if new production is just half of this, it will help to bring stability back to the market. SMI Ltd. expects gallium prices to peak in the third quarter of 2011.

Review of Work

During recent years the increasing demand of gallium in electronic and other industries has magnified the need for a simple and rapid method for the determination and recovery of gallium from aluminum ores, zinc ores, coal, fly ash etc. Following approaches have been adopted for the production at commercial scale and recovery at trace level.

Technologies required for Production at commercial scale

• Mercury Amalgamation Technology.

• Cementation Technology.

• Solvent Extraction Technology*; and

• Ion-exchange Resin Technology*.

[*The latter two technologies are typically employed for the Bayer liquors having lower concentration of gallium. However ion exchange resin technology is considered as the latest and most eco friendly process for recovery of gallium metal from Bayer liquor of alumina refinery]

Recovery from ores and industrial waste at trace level

(i)Recovery of gallium can be done by solvent extraction, which is one of the wide spread method from dilute sources.

Generally following extractants are used for solvent extraction:

(a) phosphorous containing compounds have been used for the solvent extraction of gallium(III): These are, for example, di(2-ethylhexyl) phosphoric acid (D2EHPA) tributyl phosphate (TBP) and trioctylamine (TOA). Solvent extraction stripping experiments for gallium(III) have been performed with D2EHPAin kerosene from sulphuric acid solution, but requires multistage extraction, extraction upto 87.9% only and requires high temperature. The extraction of gallium(III) from aqueous solution containing hydrochloric acid and or lithium chloride by TBP and TOA in benzene have been investigated. Micro quantities of gallium(III) from sulphuric acid leaching of secondary sublimates were extracted with TBP from hydrochloric acid solution in presence of macro components such as Fe, P, K, Na and Al. [S. K. Mohamed]

(b)Oxygen containing extractants: such as 4-ethyl, 1-methyl, 7-octyl, 8-hydroxy quinoline (Kelex 100), triphenyl arsine oxide, isobutylmethyl ketone (MIBK), 8-quinolinol and 3,5-dichlorophenol, 2,4-pentanedione, 3,5-dichlorophenol16 have been reported for the extraction of gallium(III). However, these methods suffer from drawbacks, such as long equilibrium time, low percentage recovery.

(c)High molecular weight amines (HMWA) have emerged as powerful extractants for some metals: Recently, it has been shown that the extractants Adogen 364,17 tricaprylmethyl ammonium chloride (Aliquat-336), Amberlite LA-2,tris-(2-hydroxy-3,5-dimethylbenzyl) amine (H3tdmba),23 trioctylmethylammoniumchloride (TOMAC),24 trioctylamine and TOMAC25 and the octyltrimethylammonium cation are effective extractants for the extraction of anionic complexes of gallium(III). Adogen 364 undergoes self association during extraction. Addition of a syngergist with Aliquat 336 enhances the extraction.

(d)Other extractants: Some other extractants are also  reported for extraction of gallium(III) are 3,5-dibromosalicyaldehyde acetohydrazone (DBSAH), 3,5-dibromosalicyaldehyde benzoylhydrazone (DBSBH), 3,5-dibromosalicyaldehyde isomicotinylhydrazone (DBSIH). 5-Sulfo-8-quinolinol (H2QS)28 and 2-theonyltrifluoroacetone29 have been used as extractants for gallium(III) but suffer from long phase separation time28 and low rate of extraction. Tri-n-octylphosphine oxide,30 1-(4-ethylphenyl)-3-hydroxy and 1-(4-ethylphenyl)-3-hydroxy-2-methyl- 4-pyridone31 and 2-bromodecanoic acid have also been used.

(ii)The methods for determining trace gallium at present mainly include atomic absorption spectrometry and chromatography. Photometry mainly uses fluorescent ketone, quinoline, azo and Rhodamine as colouring reagentetc.

Pre-treatment, separation and Pre-concentration

Pre-concentration procedures are often necessary for the determination of gallium because most analytical techniques do not possess adequate sensitivity for direct determination. Spectrophotometeric and other methods of analysis if the concentration of the analyte is too low to be determined or matrix interferences cannot be controlled. Several separation techniques have been proposed to solve this problem like,

(a)Liquid-liquid extraction,

(b)Ion exchange,

(c)chromatography etc.

Acid digestion is the most widely used method for pre-treatment of different types of samples prior to detection of gallium by most of the available techniques.

Pre treatments of the samples:

(a)Zinc ore: In the hydrometallurgical zinc process to treat zinc concentrate, more than 98% of the gallium comes into the leach residue. In the leach residue, a significant part of zinc remains in the form of zinc ferrite (ZnO·Fe2O3), most of gallium presents in the form of isomorphism in zinc ferrite. Because zinc ferrite is difficult to dissolve in low acid, extraction of gallium from zinc residue has a certain degree of difficulty. Dumping of residues is a solution to the problem of stockpiling site. So an economical route to extract them would serve as an incentive to carry out the extraction process. To recover the zinc and gallium, iron must be into the solution. There are two main ways to make iron into solution. One is hot acid leaching which needs high temperature and high acid concentration, the other is reductive leaching using sulfurdioxide as reductant in sulfuric acid solution. Sulfur dioxide is an efficient leaching agent for minerals containing oxides of iron, nickel, cobalt and manganese.

(b)Bauxite ore: The recovery of Ga from bauxite ores is based on the Bayer process, in which Al is extracted by hot alkaline digestion, Ga being concentrated in the Bayer liquors up to 0.19 g/L. The recovery methods of Ga from these liquors are based on Al–Ga precipitation by CO₂ and subsequent NaOH re-dissolution, on selective Ga extraction using liquid–liquid solvent extraction and ion exchange methods and on employing Hg amalgam with subsequent addition of NaOH. The Ga recovery from acidic solutions produced during Zn processing also involve liquid–liquid solvent extraction, while other Ga recovery methods from liquors include the use of insoluble amphoteric adsorbents or membranes. However, the difficulties associated with isolation of  Ga from Al always necessitate an electrolysis procedure to obtain high purity Ga end products.

(c) Coal fly ash: Two-stage leaching with hydrochloric acid is employed which fits the needs of the subsequent extraction of gallium by the foam. Before hydrochloric acid is selected, potassium hydroxide and sodium chloride are used as leaching reagents to test the extraction by an amidoxime resin and foam, respectively. The analysis of both leach solutions by AAS is identical to that of their blanks with regard to the absorbance, showing that no gallium was extracted. Two types of ashes are roasted in a muffle furnace in an air atmosphere at 500°C for 10 h before leaching to concentrate gallium. Although gallium is not lost due to sublimation under the conditions tested, the particle size of the fly ash increased, thereby decreasing the surface area and depressing the gallium leached under the mild conditions. A set of comparison experiments shows that the leaching efficiency decreases slightly [1S. Xiao-quan e.al.]

(d) Flue dust: At the beginning of leach test, sulfuric acid solution is added into the glass vessel. Heating of the solution is started and when the solution reached the desired temperature, flue dust is added. At selected time intervals, slurry sample is withdrawn, centrifuged and filtered. The filtrate is analyzed for gallium.

Methods of determination in various samples

There are quite good number of methods are  available for the determination of gallium at trace level from various waste samples.

Generally, Inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS), Atomic Absorption spectrometry, Spectrophotometery, XRD etc are used.

Literature Review

Below mentioned literature review gave us an insight about of the usage of different technologies to determine and recover gallium from various waste samples.

K. P. P. R. M. Reddy et.al (2007) proposed a simple, sensitive, and selective second order derivative spectrophotometric method  for the determination of microgram quantities of gallium(III) especially in presence of large excess of indium(III). 2-hydroxy-3-methoxy benzaldehyde isonicotinoylhydrazone (HMBAINH) chromogene was used along with 0.2% of triton X-100. The complex formed showed maximum absorption at 405 nm and at pH 5.0, where the reagent has negligible absorbance. A second order derivative spectrum of the complex solution showed maximum derivative amplitude at 415 nm and again at 460 nm with a zero cross at 442 nm. Beer's law was obeyed in the concentration range 0.036-1.533 µg/ml and 0.070-1.533 µg/ml of Ga(III) at 415 nm and 460 nm, respectively. However, at 404 nm In(III)-HMBAINH complex showed zero amplitude in the second order derivative spectrum where Ga(III)-HMBAINH obeyed Beer's law in the range of 0.070-1.394 µg/ml. This allows determination of Ga(III) in presence of large excess of In(III) by second order derivative spectrophotometric method. The tolerance limits of other diverse ions and other analytical parameters were also evaluated.

Kh. D. Nagiev et.al (2007) developed a Photometric determination of gallium in the presence of aluminum. The complexation of gallium(III) with 2,2′,3,4-tetrahydroxy-3′-sulfo-5′-nitrobenzene in the presence of and without 1,10-phenanthroline was studied. In the presence of 1,10-phenanthroline, a mixed-ligand complex with the component ratio 1 : 2 : 1 and the stability constant logβ = 15.5 ± 0.2 is formed. The different parameters like pH, time, temperature, and the concentration of components on the formation of the binary and mixed-ligand complexes of gallium were studied.

S. K. Mohamed (2006) developed an Ion selective electrode for Gallium determination in Nickel alloy, Fly-ash and biological samples.  A poly(vinyl chloride)-based membrane of 2,9-dimethyl-4,11-diphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene (DDTCT) with sodium tetraphenyl borate (STB) as an anion excluder and dibutyl phthalate (DBP), dibutyl butylphosphonate (DBBP), tris(2-ethylhexyl) phosphate (TEP) and tributyl phosphate (TBP) as plasticizing solvent mediators was prepared and used as a selective electrode to investigate Ga(III). The best result shown with the membrane having the ligand-PVC-DBP-STB composition 1 : 4 : 1 : 1, which worked well over a wide concentration range (1.45 × 10 to 0.1 mol L-1) with a Nernstian slope of 28.7 mV per decade of activity between pH 4.0 and 10.0.

N. K. Agnihotri et.al. (2004) proposed a method for non-extractive simultaneous determination of thallium(III) and gallium(III) in environmental and standard samples with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in cationic micellar medium The molar absorption coefficient and LOD of a 1:1 complex with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride were 52 500 and 0.042 ng/ml, respectively. The determination ranges of Tl3+ and Ga3+ in the presence of each other found were 0.10-2.46 and 0.04-1.05 µg/ml, respectively; the RSD for samples containing 1.23 µg/ml Tl3+ and 0.42 µg/ml Ga3+ were 1.43 and 1.65%, respectively. The method was used for the simultaneous determination of the two metal ions in environmental samples, several CRM and synthetic binary mixtures.

H. Minamisawa et.al (2004) developed a method and successfully applied to trace gallium analysis in environmental water samples. Synthetic zeolites were dissolved in nitric acid, and the resulting solution used as a coprecipitant for the preconcentration of trace amounts of gallium in water samples prior to determination by electrothermal atomic absorption spectrometry (ETAAS). The gallium preconcentration conditions and the ETAAS measurement conditions were optimized. Gallium was quantitatively concentrated with the zeolites coprecipitate from pH 6.0 to 8.0. The coprecipitate was easily dissolved in nitric acid, and an aliquot of the resulting solution was introduced directly into a tungsten metal furnace. The atomic absorbance of gallium in the resulting solution was measured by ETAAS. An ashing temperature of 400°C and an atomizing temperature of 2600°C were selected. The calibration curve was linear up to 3.0 µg of gallium and passed through the origin. The detection limit (S/N ≥ 3) for gallium was 0.08 µg/100 cm3. The RSD at 1.0 µg/100 cm3 was 3.0% (n = 5).

L. Q. Wang et.al.(2003) developed a method for Photometric determination of gallium in coal gangue. Method includes  non-ionic surfactant OP and  trihydroxyethylamine (TEA)-HCl buffer with  pH 8.5, 5-Br-PADAP which reacts with Ga(III) to form a red-colored complex with its mole ratio [Ga(III) : R] of 1 to 1 The interferences of Cu2+, Cd2+, Th4+, Fe3+, U(VI), Zn2+ and Al3+ were eliminated by the use of HCl with n-butyl acetate.

H. Filik et.al. (2002) proposed a method to determine Galliium (III) with rutin spectrophotometrically. Gallium (III) was complexed with the flavonoid ligand rutin in ammonium acetate solution at pH 7.0 The complete determination was carried out using a UV-Vis spectrophotometer at 430 nm. The effects of a cationic surfactant and its concentration and pH on sensitivity of the method were investigated. The method was applied to determining gallium (III) in the mineral sphalerite.

L. Xu et.al. (2002) determined trace gallium in lead and zinc ores by AAS.  The Sample (0.5 g) was digested  with HNO₃ , H₂SO₄ and HF. The residue produced was dissolved in 5 ml 6M-HCl prior to treatment with 15 ml 6M-HCl and TiCl₃ solution to light purple for extraction with butyl acetate. The organic phase was back-extracted at pH 2 with H₂O for flame AAS determination and Ga was measured at 294.4 nm The detection limit for Ga was 0.8 µg/ml.

Itsuo Mori et.al. (1999) used chelating azo dyes, PAR, 5-Br.PADAP along with different combination of surfactants and sample solution to develop colour for a selective spectrophotometric determination of gallium(III) without interference of aluminium(III).5-Br.PADAP in tested azo-dyes, and surfactant-combination of sodium dodecylsulfate (SDS) as an anionic surfactant and Brij 35 (polyoxyethylene)dodecylether) as a nonionic surfactant was selected for a selective determination of gallium(III) in the presence of aluminum(III).The proposed method showed a sufficient selectivity in comparison with other spectrophotometric methods using a chelating azo-dye alone without surfactant; it was scarcely affected by coexisting-aluminum(III). The method was applied to artificial waste water containing gallium(III), aluminum(III), iron(III),

Tsuo Mori et.al.(1988) developed the method for the spectrophotometric determination of Gallium (III) using o-Hydroquinonephthalein (Qnph) in the presence of surfactant micellar.  The color systems at various pH were investigated between various metal ions and Qnph as a xanthene dye as well as in the presence or absence of various water soluble surfactants (cationic. anionic, non-ionic surfactants). The coexistence of cationic and non-ionic surfactants, such as Zephiramine (Zp) and Brij 35, was found  most effective for the color systems between Qnph and gallium(III), as a metal ion, in weakly acidic media. The calibration curve was rectilinear in the range of 0∼7.0 μg of gallium(III) in a final solution of 10ml at pH 6.4.

Conclusion

With the rise in the growth of electronic industries, there is a steep rise in demand of gallium. India has potential to reduce the gap of demand of gallium due to increasing alumina production. Now it is the crucial time to develop methods by the judicial use of new technologies and sophisticated instruments for the determination and recovery/leaching of gallium from various important waste samples.

Larger amounts of gallium could be recovered from these sources if more efficient and improved extraction and separation methods are developed in the future.

Acknowledgement

We would like to thank Director, Sal Education Dr. Rupesh Vasani always providing an opportunity and providing platform to do research work.

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