- 學位論文
從切割矽泥低排放製造矽酸鈉與球型二氧化矽
Producing Sodium Silicate and Spherical Silica from Kerf Loss Silicon with Low Emission
摘要
太陽能 (PV) 行業的主要固體廢物來自於鑽石線切割損失矽泥。每年產生的廢物超過 100,000 噸。而其中一條能廢棄物利用的回收途徑是合成用途廣泛的矽酸鈉與球形二氧化矽。在這個研究中，吾人提出了一種經由矽泥和氫氧化鈉混合少量水來有效合成水玻璃的方法。主要反應於藉自身反應熱所提高的溫度下發生，而後反應則透過添加熱水進行。水玻璃的模數和濃度可以很輕易地經由調整氫氧化鈉和熱水的總量來分別控制。反應的轉化率在一小時內可高於98.5%。其中，唯一的副產品為氫氣，如有需要的話也可以收集用於其他用途。這種水玻璃也可經過酸沉澱溶凝膠，來製造球形二氧化矽奈米粒子，吾人也使用市售水玻璃來做比較，尋找合成球形二氧化矽奈米粒子的合適條件。市售水玻璃合成奈米粒子的最佳條件，乃在成核時間15分鐘的情況下，以1:8（前驅物：混合物溶液）的混合比例，使用1.4M氯化氫水溶液滴定至 pH 9，可獲得的粒徑分布在 50到270 nm之間。合成後有溶劑殘留，其中包括酒精、氨水和鹽酸，可被回收並重複使用達13次。不管是市售或是吾人合成的水玻璃，製作出的二氧化矽奈米粒子的形貌皆極相似， FTIR 和 XRD 的分析結果也差不多。這裡提出的方法，除了節能，並有超低排放的優點，適合工業的綠色生產。
並列摘要
Silicon kerf loss during wafer slicing is a major solid waste from the photovoltaic (PV) industry. More than 100,000 t of the waste is generated every year. A meaningful recycle route of the kerf-loss silicon is to produce sodium silicate and spherical silica. In this work, we proposed an efficient synthesis of sodium silicate using kerf-loss silicon by adding NaOH and a small amount of water. The main reaction took place at an elevated temperature using its own reaction heat, while the post reaction was carried out by adding hot water. The modulus and concentration of sodium silicate could be easily controlled by the amount of NaOH and hot water, respectively. The conversion of the reaction was higher than 98.5% in an hour. Only hydrogen gas was produced as by-product and could also be collected for other applications if necessary. Afterward, this sodium silicate was a precursor for spherical silica nanoparticle by sol-gel with acid precipitation. To try conditions that are appropriate for spherical silica nanoparticle synthesis, commercial sodium silicate was firstly employed. The best condition produced from commercial sodium silicate used 1:8 (precursor: mixture solution) at 15 minutes of aging time by titrating with 1.4M of HCl to pH 9. Particle size distribution was obtained from this condition was in the range from 50 to 270 nm. From this synthesis, there was supernatant which included EtOH, NH4OH and HCl which can be recovered and reused to synthesize silica nanoparticle up to 13 cycles. Later, as-prepared sodium silicate was synthesized to spherical silica nanoparticle by the best condition procedure. According to SEM analysis, particle morphology of the spherical silica nanoparticle produced from kerf loss sodium silicate were similar to those produced from commercial sodium silicate. From FTIR and XRD analysis, the structure of spherical silica nanoparticle obtained from kerf loss sodium silicate and commercial sodium silicate were still similar. The proposed process was found efficient, green, environmentally benign, and cost effective and low emission.