利用酸鹼中和法由氯化銅酸性蝕刻廢液製備奈米氧化銅微粒之研究

Preparation of CuO Nanoparticle from Copper Chloride-Containing Wasted Etchant by Alkali Neutralization

林忠舜(Jung-Shuen Lin)

指導教授 ： 林錕松

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

印刷電路板廠每年排放約6000萬公升的含10-15%銅蝕刻廢液，目前於業界中大都使用分流或儲存委外處理方式；因此本研究主要目的為使用在印刷電路板業中含銅量較高之酸性含氯化銅蝕刻液，其中主要組成成份為氯化銅、鹽酸及水；因而使用酸鹼中和法將酸性蝕刻廢液製備成為奈米氧化銅微粉，以達廢棄物資源再利用之永續經營。
本實驗使用之酸鹼中和法可分為水浴法與超音波震盪法兩種，其中中和法又分為鹼酸及酸鹼中和滴定方式進行，並控制不同pH值、反應溫度及煅燒溫度，製備不同晶相形狀及顆粒大小的奈米氧化銅粉末，在中和反應蝕刻液添加NaOH溶液時，當溫度低於40℃且pH = 5-8時形成氧氯化銅CuO2．2CuCl，而pH = 9則形成Cu(OH)2；不過在高於40℃且pH＞10時，則轉變成為CuO。藉由場發掃描式電子顯微鏡(FE-SEM)及穿透式電子顯微鏡(TEM)觀察不同反應溫度之產物，溫度低於40℃以下形成棒柱狀，高於40℃則形成片狀結構；使用超音波震盪方式可得到長150-400 nm、寬25-100 nm的奈米氧銅微粉;比較此三種合成奈米氧化銅方法，在鹼酸中和反應時因反應溫度的不同而由膠狀形成顆粒狀，而導致在較低溫時不易攪拌；酸鹼中和反應時當溫度高於40℃時即形成氧化銅微粉且易於攪拌；使用合成效較佳的超音波震盪法，可增快合成反應速率，所生成之氧化銅微粉具顆粒細小及反應時間短的優點。
使用熱重法(TGA)分析不同pH値下所合成之氧化銅產物，其中pH > 12時，氯離子含量才可能被完全移除。另外，利用X-ray粉末繞射儀(XRPD)比較不同pH值之晶形結構，pH由10~12時晶形結構由氧氯化銅成為CuO微粉。為了深入瞭解奈米CuO產物之表面精細結構，進一步使用光電子能譜儀(XPS)及電子順磁共振儀(EPR)對奈米氧化銅微粒進行分析，在Cu 2p3/2能階顯示為Cu(II)及平面四方型結構，由此推斷本實驗所製備出之奈米氧化銅微粒主要為CuO而非Cu2O的結構。經由延伸X光吸收精細結構及X光吸收邊緣結構(EXAFS/XANES)分析銅的氧化價數主要為2價，Cu-O鍵距為1.94±0.02 Å，配位數為3.5±0.1。由ICP/AES分析奈米氧化銅粉之銅離子濃度，金屬銅含量達99% ，且生成之副產物主要有氯化鈉、水及微量Zn、Pb、Ni、Mn、Cr金屬，符合PCB廠CuO回收再利用為原料之基本品質規範。
關鍵詞：印刷電路板、氯化銅蝕刻液、酸鹼中和法、水熱及超音波震盪法、奈米氧化銅、X光吸收邊緣結構、延伸X光吸收精細結構。

關鍵字

印刷電路板 ； 氯化銅蝕刻液 ； 酸鹼中和法 ； 水熱及超音波震盪法 ； 奈米氧化銅 ； X光吸收邊緣結構 ； 延伸X光吸收精細結構

並列摘要

At present, over 60 million liters per year of 10-15 % copper-containing waste etchants (CCWEs) generated from printed circuit board (PCB) manufacturing are disposed of in Taiwan. The CCWEs are mainly composed of copper chloride, hydrochloric acid, and water. Since the disposal of the etchants without proper treatment has posed an environmental problem, the separation or storage method have been previously used. Therefore, resource recovery of these undesired waste etchants in the form of high-purity CuCl2, would be economically and environmentally attractive.
Experimentally, the CuO nanoparticles were recovered from CCWEs by using hydrothermal and ultrasonic neutralization with alkali hydroxide. The control factors of the synthetic experiments included the neutralization types, pH values, reaction temperatures or calcined temperatures of CuO products. In the neutralization process by addition of the NaOH into the CCWEs, the precipitates of CuCl2．3Cu(OH)2 and Cu(OH)2 were formed below 40℃at pH = 5-8 and 9, respectively. However, the CuO nanoparticles were produced above 40℃ and pH＞10. The properties of liquid residues and CuO precipitates were further analyzed by using ICP/AES, XRD, FESEM, TEM, XPS, EPR or EXAFS/XANES spectroscopy. From the FE-SEM microphotos, needle and slit shape CuO residues were found below and above 40℃, respectively. The comparison of the results for hydrothermal forward- or backward-neutralization with ultrasonic neutralization methods, the later one had the advantages of shorter reaction times and smaller CuO particles with diameters of approximately 25-100 nm and lengths of 50-400 nm.
By using TGA method, the chlorine-free CuO nanoparticles were formed and confirmed at pH > 12. The XRPD patterns showed the precipitates transformed from CuCl2．3Cu(OH)2 to CuO at pH = 10-12. Existence of the Cu(II) was also confirmed by XANES and XPS spectroscopy. The CuO nanoparticles with a square-plane structure were observed by EPR spectra. The CuO nanoparticle with a Cu-O bond distance of 1.94 ± 0.02 Å and a coordination number of 3.5 ± 0.1 was also measured by EXAFS spectroscopy. From ICP/AES data, more than 99% of the copper in CuO recovered from CCWEs. The major by-products in recovered CuO nanoparticles were NaCl, H2O, and trace heavy metals such as Zn, Pb, Ni, Mn or Cr.
Keywords: PCB, Copper chloride etchant waste, Alkali Neutralization, Hydrothermal and ultrasonic neutralization, CuO nanoparticles, XANES, EXAFS.

並列關鍵字

PCB ； Copper chloride etchant waste ； Alkali Neutralization ； Hydrothermal and ultrasonic neutralization ； CuO nanoparticles ； XANES ； EXAFS

參考文獻

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