商用的奈米銀噴霧產品產生的奈米微粒特性分析

Abstract

本研究分析商用3種含銀噴霧器所產生的噴霧氣膠與噴霧中的ENP特性。在噴霧氣膠量測部分，本研究使用風洞系統進行噴霧逸散後數目濃度、粒徑分佈情形，並結合TEM與EDX分析，以了解微粒的形貌與化學成分。實驗結果顯示，噴霧氣膠粒徑分佈與數目濃度會因為噴頭型式而有很大的區別。噴霧A(幫浦式噴頭)產生少量奈米氣膠，而噴霧B與C(壓縮氣體是噴頭)的氣膠粒徑皆產生大量奈米氣膠，此奈米氣膠為噴霧逸散過程中，由壓縮氣體絕熱膨脹過程所產生的核凝態微粒。在噴霧逸散過後，微粒總數目濃度會急遽上升至最高點，並依照噴霧器所噴出微粒數目濃度的高低，在20-60秒後降回背景數目濃度，顯示即使在通風良好的環境內，人體仍有可能有很高的微粒暴露風險。在質量濃度分佈的部分，MOUDI測得噴霧A、B、C的總質量濃度分別為45.15 μg/m3、123 μg/m3、156 μg/m3 ，ELPI測值分別為41.79 μg/m3、115.67 μg/m3、145 μg/m3， 前者的總質量濃度測值比後者高出了分別約8%、6%、8%。3種噴霧的TEM/EDX分析結果顯示，噴霧A含有銀成分的纖維，且伴隨著碳元素訊號，此碳元素訊號可能來自TEM碳膜網中的成分或ENMs合成過程所添加的碳酸氫鈉。噴霧B與C有圓球形與不規則形狀的微粒與團聚體，部分微粒有一層膠狀物質包覆，顯示噴霧中的ENMs會與噴霧溶劑與添加物交互作用，形成成分複雜的混合物質。另外噴霧B、C的EDX分析顯示碳、氧、矽元素成分佔了80%以上，碳元素來自於TEM碳膜網或噴霧中的推進劑成分，而氧與矽來自噴霧溶劑矽油(SiO2)的成分。 噴霧中的ENP量測方面，本研究參考傳統TD(thermo denuder)的設計，並根據PMP(particle measurement program, PMP)方法，發展一套由加熱段、稀釋段、吸附段3段式揮發性微粒去除方法。本研究調整加熱段的溫度與稀釋段的稀釋倍率，當加熱段溫度由30℃持續上升至200℃時且稀釋倍率為1:10時，噴霧B與C氣膠微粒數目濃度先下降至原本的8.6%與16.3%，而後些微上升，且眾數粒徑隨著溫度上升持續增加，顯示微粒有團聚作用。 本研究也研究三種噴霧器的銀逸散因子，以作為後續風險評估的參考，噴霧器的銀逸散因子可以分為液體銀逸散與氣膠銀逸散。實驗結果顯示三種噴霧液體銀濃度分別為207 ppmw 、31.77 ppmw與20.51 ppmw，逸散因子計算結果顯示三種噴霧的液體銀逸散量差異不大，均藉於20~30 μg/次，而總氣膠銀逸散因子分別為38、170、380 ng/次，雖然噴霧A液體銀濃度最高，但是噴霧A每次按壓噴霧逸散量少，相對的，噴霧B與C雖然氣膠含銀量不高，但是噴霧量分別是A的5倍與10倍，每次按壓會逸散大量氣膠，導致銀的逸散因子高於A，故噴頭機制微影響氣膠銀逸散因子的主要因素。

In this study, the spray aerosols and ENPs released from the silver-containing commercial spray products are characterized. With regard to the spray aerosols, the number concentration and size distribution are measured using a wind tunnel, and TEM/EDX analyses are also conducted to get the insight to the morphology and the chemical compositions of particles.The results show that the size distribution and number concentration of spray aerosols largely depend on spray disperser type. SprayA merely releases few nano-sized aerosols, while sprayB and C release significant nano-sized aeaosols, which are the nuclei mode particles produced by adiabatic expansion during spray process.After spray is released, total particle concentrations will first dramatically increase to maximum, followed by decrease to background concentration in 20~60 seconds dependent of its maximum concentration, which means human body still have high exposure risk even in good ventilation. On the other hand, the mass concentration of sprayA, B and C measured by MOUDI are 45.15 μg/m3, 123 μg/m3, 156 μg/m3, while these are 41.79 μg/m3、115.67 μg/m3、145 μg/m3 by ELPI, respectively, the formal are 8%, 6%, 8% higher than the later. Besides, TEM/EDX analyses show that sprayA contains silver fiber coupled with carbon signal. This carbon signal is either from the carbon based membrane on TEM grid or soldium hydrogen additive during ENMs formation.The morphology of spray B and C particles are various, from roundish particles to multiple shape agglomerate. It can be found that part of particles are coated with matrix, indicating the ENMs in spray dispersion can interact with spray solvent and additives to form complex compound. The EDX result of spray B and C shows that carbon, oxygen, silica signal occupy more than 80% of total mass. Carbon signal is either from the TEM grid or the components of spray propellant, while oxygen and silica signal are from silicon dioxide solvent. Based on thermo denuder(TD) and particle measurement program(PMP), this study develop a three stage method, that is, heating section, dilution section and denuder section, to try to eliminate the volatile matter. When the temperature of heating section rises from 30℃ to 200℃ with 1:10 dilution, aerosol number concentration of sprayB and C decrease to 8.6% and 16.3% of its initial number concentration, than slightly increase as mode diameter increase with rising temperature, showing certain level of particle agglomeration effect. The silver emission factors of three types of spray, including liquid siver emission and silver aerosol emission, are also analyzed in this study as the basis of further risk assessment. The result shows that spray dispersion are 207 ppmw, 31.77 ppmew, 20.51 ppmw, respectively. The liquid silver emission shows little difference among products, all between 20~30 μg per sequeeze, while total silver aerosol emission factors are 38, 170, 380 ng per sequeeze. Although the liquid silver concentration of spray A is the highest, but the amount of aerosol released is only 1/5 and 1/10 compared with spray B and spray C, resulting in the silver emission factor is less than B&C, meaning the spray mechicism is the critical factor affecting the silver emission factor.