研究成果發表文章

1. Mann Juin Kao, Shao Fu Chang, Chin Guo Kuo, Chia Chih Wei, *Chien Chon Chen, “The Silver Recovery from Used Keyboard”, (Accepted) (EI)

2. Mann Juin Kao, Shao Fu Chang, Chin Guo Kuo, Ker Jer Huang, Chien Chon Chen*, “The Formation of Anodic Aluminum Oxide on the Si Wafer”, 2013 Symposium on Nano Device Technology, NMI19, 4 pages, Taiwan (2013)

3. Mann Juin Kao, Shao Fu Chang, *Chien Chon Chen, * Chin Guo Kuo, "The

Surface Adsorption of Nano-pore Template", World Academy of Science,

Engineering and Technology, (2012) 800-803. (EI)

4. Shao Fu Chang,Mann Juin Kao, Chin Guo Kuo, Ker Jer Huang,Chien Chon Chen^*, “Design, Characterization, and Development of Large-Scale Nano Thermal

Insulating Film”, 2013 Symposium on Nano Device Technology, NMI06, 3 pages,

Taiwan (2013)

5. Shao Fu Chang, Mann Juin Kao, Chin Guo Kuo, *Chien Chon Chen, Ker Jer Huang, “The Deposition Methods of CsI and Ni Tubes in the AAO Template”, Applied Mechanics and Materials, 275-277(2013) 2256-2260 (EI)

6. Shao Fu Chang, Mann Juin Kao, *Chien Chon Chen, Chin Guo Kuo,

“Fabrication of CsI Nanocrystals on the AAO Template by Liquid Phase

Deposition Method”, 2012 Japan-Taiwan Symposium on intelligent Green and

Orange (iGO) Technology, p. 26-27, Taiwan (2012).

7. *Chien Chon Chen, Shih Hsin Chen , Shao Fu Chang, Mann Juin Kao, Wern Dare Jheng, Shing Hoa Wang, “The Decomposition Mechanism of Titania Film

with Nanotube Structure”, Advanced Materials Research, 189-193 (2011)

2660-2664 (EI)

8. Chien Chon Chen, Shao Fu Chang, Mann Juin Kao, Wern-Dare Jehng, *Wang Shing Hoa, “Fabrication of Thermo-conductivity Film Using Anodic Aluminum

Oxide Template and Silver Nanowires”, Advanced Materials Research, 146-147

(2011) 22-25 (EI).

9. 陳建仲*, 郜曼君, 張紹甫, 陳士新, “製作大面積染料敏化太陽能電池的模

具”, 九十九年度中國材料科學學會論文集, 0014, 高雄

附件一



Abstract—Electronic device industries heavily depend on silver. The industry produces large quantities of silver paste and wastewater, containing high concentrations of silver compounds. This study offers a valuable method for recovery of pure silver from used materials using hydrometallurgical and pyrometallurgical processes. The hydrometallurgical method (displacement) can be used to obtain silver metal from the used keyboard. The mylar film of keyboard was first dissolved in the hydrogen peroxide (H₂O₂) and nitric acid (HNO₃) solution to obtain silver ion. Then, the pyrometallurgical (slag making) method can be used to upgrade silver film or particle to pure silver metal. The silver recovery mechanisms were described by the Gibbs free energy and Nernst equations.

Keywords— silver paste, recovery, hydrometallurgical, pyrometallurgical , mechanisms

I. NTRODUCTION

ILVER is a precious metal having wide range applications in 3C products, battery, solar cell, and photographs. It presents very good properties of thermal and electrical conductivity. Silver is a valuable natural resource of finite supply, it has monetary value as a recovered commodity. The most widely used silver recovery method for large operations is electroplating where the silver is recovered from solution by it on a cathode. Silver is deposited on the cathode in the form of nearly pure silver plate. When properly operated, 95% of the potential available silver can be recovered [1, 2]. The mainly silver recovery steps from waste films can be summaries as separation of the silver source from the films base, oxidation of the metallic silver following electrolysis, collection of silver film from the electrolyte, and smelting the sliver film forming silver ingot [3].

Used electronic equipment became one of the fastest

M.J. Kao, ¹Department of Industrial Education, National Taiwan Normal University, Taipei,,Taiwan (e-mail: [email protected]).

S.F. Chang,¹Department of Industrial Education, National Taiwan Normal University, Taipei,,Taiwan (e-mail: [email protected]).

C.G. Kuo, ¹Department of Industrial Education, National Taiwan Normal University, Taipei, Taiwan (e-mail: [email protected]).

C.C. Wei, ²Department of Energy Engineering, National United University, Miaoli, Taiwan(e-mail:[email protected])

C.C Chen, ²Department of Energy Engineering, National United University, Miaoli, Taiwan(phone: +886-37-382383; fax:+886-37-382-39; e-mail:

[email protected])

growing waste streams in the world. Large amount of waste electrical and electronic equipment (WEEE) are generated each year, bringing significant risks to human health and the environment. The electronic equipment of keyboard is a very simple device without many parts and pieces. The keyboard including a piece of mylar material covered with small grey dots and lines [4]. In this study, recovery of silver from mylar sheet of used keyboard processing effluents by precipitation was studied. Hydrogen peroxide (H₂O₂) was used as the precipitating agent and nitric acid was used as the solvent. The precipitation of silver by H₂O₂ is a fast reaction [5]. The addition of ethylene glycol enhanced the recovery of Ag presumably due to its stabilizing effect on H₂O₂. The final step of smelting process, the molten silver will contain dissolved oxygen which must be removed before the silver is allowed to solidify. The oxygen can be removed by contacting the melt with carbon which reacts with the dissolved oxygen to form CO₂ preferably, the oxygen is removed by inserting a carbon rod into the melt until evolution of CO₂ ceases indicating removal of all oxygen.

II. Experimental procedure

The silver paste film of keyboard was first dissolved in the hydrogen peroxide (H₂O₂) and nitric acid (HNO₃) solution to obtain silver ion. Then, the pyrometallurgical (slag making) method can be used to upgrade silver film or particle to pure silver metal. The fabrication processes for silver recovery of the following steps:

i. Immerse the sliver paste in the nitric acid (HNO3) solution.

ii. Dissolve the silver ion into the solution at 100℃.

iii. Filter the impurity from the solution.

iv. Evaporation the over nitric acid (HNO₃) and add water to drop the solution pH value.

v. Mix some thiourea in AgNO_3(aq) to let the Ag ion stable.

According to above steps we can obtain the AgNO_3(aq) which is contain the Ag ion, then repeat evaporation the over nitric acid (HNO₃) and add water (step iv) can be used to upgrade silver film or particle to pure silver metal or we can put the copper into the soultion, there were cover a layer of Ag_(s) from the AgNO_3(aq) on the copper surface.

III. Results and discussion

Immersing the sliver in electrolyte generated various substances. They included solids of Ag_(s), Ag₂O_2(s), and AgO , ions of [Ag⁺] and [Ag(OH)^-], and solution of

1Mann Juin Kao, ¹Shao Fu Chang, ¹Chin Guo Kuo, ²Chia Chih Wei, ²Chien Chon Chen^*, ³Ker Jer Huang

The Silver Recovery from Used Keyboard

S

of silver in aqueous solution. The Pourbaix diagram (Figure 1) is useful in simplifying the complex reaction. The diagram is constructed by considering the Gibbs free energy and the Nernst equation. The silver is a noble metal. The Ag Pourbaix diagram domain of stability covers a very large portion of the domain of stability of water and aqueous solution. It is not attacked appreciably by dry or moist air. However, when an electrode potential of over 0.5V (SHE) (which corresponds to

an ion concentration of 10^-6 and pH=7) is applied an ion of reductive silver film on a copper sheet from AgNO₃ solution, (c) a silver film can be corrected by a adhesive tape silver film from a copper sheet, (d) scraped and collected silver film from a copper sheet, (e) a noble metal of silver which without oxide forming when it was melt in an atmosphere. Silver pellet can there be formed by smelting used a butane (C₄H₁₀) torch.

The silver chemical reaction and mechanism of silver

can be formed, the reaction equation as:

3 Ag_(s) + 4HNO_3(aq) → 3 AgNO_3(aq) + 2 H₂O_(l) + NO_(g) (1) Silver chloride is an insoluble in water, but the silver nitrate is a highly soluble in water. The solubility of AgNO₃ in H₂O is 122 % (0 °C), 216 % (20 °C), 440 % (60 °C), 733 % (100 °C), respectively. Based on the Nernst equation (E=E^o+(RT/nF)lnK) and Gibbs free energy (△G^o=-nFE^o) [7]. The free energy equation states that the maximum cell potential is directly related to the free energy difference between the reactants and the products in the cell. The spontaneous reaction with △G<0 but, the non-spontaneous reaction with △G>0. A positive E^o value corresponds to a negative △G^o, which is the condition for spontaneity.

The Eqn. 4 can be expressed as two half-reactions of Eqns. 5 and 6.

Cu²⁺_(aq)+2e^-→Cu(s) 0.34V E_Cu=0.34+(RT/2F)ln(1/Cu²⁺) (5)

Ag⁺_(aq)+e^- →Ag_(s) 0.80V E_Ag=0.80+(RT/F)ln(1/Cu²⁺) (6)

In order to obtain the spontaneous reaction of △G<0 the value E must be a negative (n and F are the constants of positive balanced oxidation-reduction reaction of Eqn. (7), the standard potential value E^o=0.46V.

IV. Conclusions

Silver can be recovered from an acidic solution of used keyboard using simple hydrometallurgical and smelting techniques. Silver ion was first formed from in the H₂O₂ + HNO₃ solution. Silver film and pellet was later formed through Galvanic reaction and hot smelting method. This work demonstrated a simple and robust silver recycling process, explained the chemical and metallurgic reactions step-by-step from a thermodynamic viewpoint. This simple process can potentially be extended to recovery of other high cost metals such as gold, copper, and gallium from industrial solutions.

ACKNOWLEDGMENT

The authors gratefully appreciate the financial support of the National Science Council of ROC under the contract No.101-2627-M-239-001-.

This work was financially supported by the Chung- Shan Institute of Science and Technology (CSIST) under the

(a) (b)

(c) (d) (e)

NSC 100-3113-S-262-001-.

REFERENCES

[1] A. Troupisa, A. Hiskiaa, E. Papaconstantinou, Photocatalytic reduction—recovery of silver using polyoxometalates, Applied Catalysis B 42 (2003) 305.

[2] Y.B. Sua, Q.B. Lia, Y.P. Wangb, H.T. Wangb, J.L. Huangb, X. Yangb, Electrochemical reclamation of silver from silver-plating wastewater using static cylinder electrodes and a pulsed electric field, Journal of Hazardous Materials 170 (2009) 1164.

[3] A.P. Paiva, Review of Recent Solvent Extration Studies for Recovery of Silver from Aqueous Solutions, Solvent Extraction and Ion Exchange 18 (2000) 223.

[4] G.C. Stevens, M. Goosey, Materials Used in Manufacturing Electrical and Electronic Products, Electronic Waste Management (2008) 40.

[5] O.G. Gromov, A.P. Kuz'min, G.B. Kunshina, E.P. Lokshin, V.T. Kalinnikov, Electrochemical Recovery of Silver from Secondary Raw Materials, Russian Journal of Applied Chemistry 77 (2004) 62.

[6] M.Pourbaix, Atlas of Electrochemical Equilibria in Aqueous Solution, NACE International Cebelcor, (1974) 393, USA.

[7] William D.C., Materials Science and Engineering, 3^rd edition, John Wiley & Sons, Inc., (1994) 553, USA.

Figure 2 The optical images of silver recovery from the keyboard; (a) a used keyboard with silver paste on the surface, (b) the reductive silver film on a copper sheet, (c) remove silver film from a copper sheet used a adhesive tape, (d) scraped and collected silver film from a copper sheet, (e) melt silver film and from a silver pellet.

附件二

The Formation of Anodic Aluminum Oxide on the Si Wafer

1Mann Juin Kao, ¹Shao Fu Chang, ¹Chin Guo Kuo, ²

Ker Jer Huang,

³Chien Chon Chen^*

1Department of Industrial Education, National Taiwan Normal University, Taipei, Taiwan

2Chung-Shan Institute of Science and Technology, Taoyuan, Taiwan

3Department of Energy Engineering, National United University, Miaoli, Taiwan

Abstract

Most electronic and optolelctronic devices are based on high-quality semiconductors process. It will be highly if the self-assembly nanofabrication techniques can be combined with traditional micro-fabrication technologies in the pursuit of next generation high performance nano-scale devices. Based on the technique of AAO forming on Al foil, AAO on Si wafer and glass substrate can be achieved in our experiment. The AAO bottom of barrier layer on the Si, glass/AAO interface always decreases the electron conductivity transparency. For this reason, the barrier was removed by the process of applied 10 V pulse voltage.

Introduction

Nanotechnology is not so much a new technology, as it is a new concept for materials and device fabrication processes. The key to successful fabrication of nano-materials is understanding how to control process parameters correctly. When anodized in an acidic electrolyte and controlled under suitable conditions, aluminum forms a porous oxide called anodic aluminum oxide layer with approximately hemispherical geometry.

Aluminum in the presence of air or aqueous electrolytes is always covered with a thin natural layer of alumina. When a positive voltage is applied to an aluminum substrate in a suitable electrolyte, pores form on the surface in almost random positions. However, under specific conditions, almost perfect hexagonally ordered pores in anodic alumina can be obtained.

When aluminum reacts with acid for example, sulfur acid and under an applied voltage the reaction includes Eqns. 1~4. The Al Pourbaix diagram can therefore be created using the equations.

 area can be computed based on AAO structural parameters.

These parameters include AAO thickness, pore size, pore density, and sample size. It is generally accepted that the thickness of barrier-type alumina is mainly determined by the applied voltage (1~1.4 nm/V) [6], even though there are slight deviations depending on the electrolytes and temperature. The maximum attainable thickness in the barrier-type alumina film was reported to be less than 1 μm, corresponding to the breakdown voltage in the range of 500~700 V (DC) [7-9]. Akahori [10] has demonstrated that the melting point of this inner oxide layer is 1000 C, also the AAO template is stable around 800°C [11], which is much lower than that of the bulk alumina.

Figure 1 The schematic diagrams of AAO; (a) the

oxalic acid (COOH)₂ or phosphoric acid (H₃PO₄). The TiN and Al film was deposited onto 6 inch Si wafer using a 4-inch TiN and Al targets with a purity of 99.999%. The base pressure of the deposition chamber was kept at 1×10^-6 Torr. Working pressure was 5×10^-4 Torr, and sputtering power during deposition was 100 W, 50 V bias, applied for 20 min. A 15 nm pore diameter template was then fabricated by anodizing the polished Al substrate at 10 V in 10% vol. H₂SO₄ at 0 ℃ for 5 min, which is called the first anodization. In order to obtain an orderly pattern on the substrate for the second anodization, the first pore diameter AAO template; the electrolyte was 3% vol.

(COOH)₂ at 10 ℃, the applied voltage was 40 V, and the time for pore widening is 30 min [12-16].

Results and Discussion

When aluminum is immersed in the H2SO4 or H3PO4

electrolyte, H2SO4 is ionized to SO²₄^ and 2H^ (reaction 5). Based on the Al Pourbaix diagram, applying a voltage to the aluminum ionizes Al to Al³⁺ (reaction 6), establishing the basic conditions (Al³⁺, acid region) for anodizing aluminum. In aqueous solution, water ionizes to H⁺ and OH^-. A H⁺ ion gains an electron formation H atom, then a pair of H combines to form H₂ after gaining double electrons from Al, escaping from the sample surface.

During the anodization, hydrogen gas escapes through the alumina tube, and Al³⁺ can be extracted from the Al surface, and the Al/oxide interface to form the nano-pattern structure. Therefore, Al³⁺ associates with OH^- (reaction 7) or O^2- which comes from air (reaction 8) exothermic reaction, where H⁰_f is standard enthalpy.

kJ

In above equations, the heat of exothermic in Eqn. 6 can be removed before anodization when cooled down the solution in the isothermal tank. The local heat in Eqns. 7 and 8 should be removed by cycling or agitating electrolyte, otherwise the local cracking, pits, defects present on the AAO surface.

Different architectures of AAO are developed, including AAO attached to Al foil, and free-standing AAO glass or Si wafer. The characteristics of AAO that the pore channels penetrate through the whole oxide film without interconnections, and the pore diameters are controllable between 10 to 500 nm. AAO forms on a Si wafer which is compatible with Si planar techniques and hence can be used to fabricate various nanostructure of integrated circuits (IC) devices by the semiconductor processes.

However, the process unsuitable includes the lasting heat treatment step because Si would solve in Al film.

According to Al-Si binary phase diagram the maximum solubility of Si in Al is 1.5 at.% at the eutectic temperature (577℃), and it decreases to 0.05 at% at 300℃. When the second phase of Si solved in Al, it will make sub-holds in AAO. As well as, the coefficient of linear thermal expansion between Si (22 × 10^-6/K) and ceramic AAO (very low) is very different at high temperature it makes AAO falling off Si wafer easily. Therefore the interlayer of TiN between Si wafer and Al film should be formed.

Figure 2 showed the images of AAO on Si wafer; (a) optical image of AAO on a 6 inch Si wafer, (b) SEM can growth on the Al grains even on the micron size of Al grain boundaries of wafer substrate. Figure 3 images of AAO on Si wafer; (a) and (b) SEM image of AAO formation on the Al micro-grains, (c) AAO with 80 nm pore diameter, (d) side view images of straight AAO channel without barrier layer on Si wafer.

The thickness of barrier layer is mainly determined by the anodizing voltage although there is a slight deviation depending on the anodization electrolyte and temperature.

Early experimental studies on the morphology and mechanism of pore formation on aluminum films showed that the barrier layer thickness is proportional to the anodization voltage. Accordingly, the thicknesses of the barrier layer of the templates used in this study are estimated to be ~18 nm and ~40 nm for AAO (φ15 nm) and AAO (φ60 nm) templates respectively and hence the significant difference in etching time. A thin film of barrier layer has similar chemical composition with AAO.

Also, the thickness of barrier layer is similar to AAO pore wall. The isotropic etching would be happen during wet etching. It is difficult to keep AAO well but remove or dissolve barrier layer by just chemical etching method.

However, when applied pulse voltage to the specimen the barrier layer is closer to electrode (anodic) than AAO pore wall. Therefore, the short time electrochemical etching by pulse voltage method can remove barrier layer but retains AAO.

Figure 2 images of AAO on Si wafer; (a) optical image of AAO on a 6 inch Si wafer, (b) SEM image

Figure 3 images of AAO on Si wafer; (a) and (b) SEM image of AAO formation on the Al

Conclusions

In nano-technology research, fabricating functional nanoscale structures and devices in a well-controlled way represents one of the most difficult challenges facing researchers and engineers. Due to the small dimensions of these nanoelements, the AAO template process provides a viable approach to overcoming such technological challenges. AAO with 10 and 80 nm pore sizes were formed on the Si wafer by 10 vol.% H₂SO₄ (10V) and 3%

vol. (COOH)₂ (40V) anodization method. The T interlayer of TiN between Si wafer and Al film can prevented Al-Si alloy and sub-holds form on the AAO. The straight AAO channel without barrier layer on Si wafer was achieved by pulse voltage method.

Acknowledgment

The authors gratefully appreciate the financial support of the National Science Council of ROC under the contract No.101-2627-M-239-001-, 101-3113-S-262-001-, and Chung-Shan Institute of Science and Technology (CSIST) under the contract No.(CSIST-442-V202).

References

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[6] O’Sullivan JP, Wood GC, The Morphology and Mechanism of Formation of Porous Anodic Films on Aluminum, Proc. Royal Soc. London A, 1970;317:511-543.

[7] Diggle JW, Downie TC, Goulding CW, Anodic Oxide Films on Aluminum, Chem. Rev., 1969;69:365-405.

[8] Hunter MS, Fowel P, Determination of Barrier Layer Thickness of Anodic Oxide Coatings, J. Electrochem.

[9] Hunter MS, Fowel P, Factors Affecting the Formation of Anodic Oxide Coatings, J. Electrochem. Soc., Nanotubes Growth in Anodic Alumina Nanoholes Appl. Phys, Lett., 1999;75:2044-2046.

[12] Chen SH, Chen CC, Luo ZP, Chao CG, Fabrication and characterization of eutectic bismuth-tin (Bi-Sn) nanowires, Mater. Lett., 2009;63:1665-1668.

[13] Say WC, Chen CC, An Efficient Technique for the Fabrication of Nano-size pasrticles of Lead-Bismuth Alloy, Jpn. J. Ceramic Soc., 2008;116:288-290.

[14] Say WC, Chen CC, Formation of Tin Whiskers and Spheres on Anodic Aluminum Oxide Template, Jpn.

J. Appl. Phys., 2007;46:7577-7580.

[15] Chen CC, Y Bisrat, Luo ZP, Schaak RE, Chao CG, Lagoudas DC, Fabrication of Single Crystal tin Nanowires by Hydraulic Pressure Injection, Nanotechnolo., 2006;17:367-374.

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附件三

附件四

Design, Characterization, and Development of Large-Scale Nano Thermal Insulating Film

1Shao Fu Chang, ¹Mann Juin Kao, ¹Chin Guo Kuo, ²Ker Jer Huang, ³Chien Chon Chen^*

1Department of Industrial Education, National Taiwan Normal University, Taipei, Taiwan

1Department of Industrial Education, National Taiwan Normal University, Taipei, Taiwan

在文檔中 銀的回收與奈米銀線製作之研究 (頁 80-120)