近年來，環境汙染的問題越來越嚴重，因此，能夠找到解決環境汙染的方法，是很多人的研究目標。奈米鈣鈦礦結構的礦物，具有催化能力或光催化的性質，可以達到自我清潔及催化分解污染物之功效。例如：LaCrO3及LaNiO3能夠催化分解引擎廢氣CO或NOx等。另外，礦物奈米化後由於具有大的比表面積，因此可用來吸附有害的重金屬污染物。
本研究主要是以簡單、便宜的共沉澱法合成具鈣鈦礦結構的奈米鈦酸鍶與鈦酸鋇。因為奈米鈦酸鋇之光催化效果優於奈米鈦酸鍶，故之後改變起始原料的比例，合成出三種不同粒徑大小的奈米鈦酸鋇。最後，針對三種不同粒徑的奈米鈦酸鋇對亞甲基藍有機染料的光催化分解及銅/鉻離子的吸附加以探討。
根據XRD分析之結果，得知合成出來的奈米鈦酸鍶與奈米鈦酸鋇皆為立方晶系。藉由TEM的觀察，得知奈米鈦酸鋇粒徑範圍約為80~110nm，奈米鈦酸鍶則為60~100nm；另兩種不同粒徑之奈米鈦酸鋇粒徑則為25及75nm。由UV-Vis光譜分析儀得知奈米鈦酸鋇及奈米鈦酸鍶之能隙各為3.39eV及3.43eV；而另二種不同粒徑之奈米鈦酸鋇則為3.38及3.37eV。由BET的分析得知奈米鈦酸鋇及奈米鈦酸鍶之比表面積各為2.72及9.98(m2/g)；而粒徑約在25nm之奈米鈦酸鋇具有最大的比表面積，約36.32(m2/g)；75nm之奈米鈦酸鋇則為23.97(m2/g)。
在有機染料光催化實驗中，奈米鈦酸鋇的光催化效果略優於奈米鈦酸鍶，而平均粒徑大小在75nm的奈米鈦酸鋇，它的光催化是效果最好的。
在銅離子吸附實驗中，經由動力吸附及等溫吸附模式的計算後，可知粒徑分佈較廣的奈米鈦酸鋇是符合假一階的吸附，而25nm及75nm的奈米鈦酸鋇則是符合假二階的吸附，且都符合Langmuir 之等溫吸附模式。粒徑分佈較廣的奈米鈦酸鋇其最大吸附量為20.53(mg/g)；25nm之奈米鈦酸鋇，其最大吸附量為28.49(mg/g)，而75nm的奈米鈦酸鋇其吸附量則為26.25(mg/g)。
在鉻離子吸附實驗中，經由動力吸附及等溫吸附模式之計算發現：25nm、75nm及95nm的奈米鈦酸鋇是符合假二階的吸附，且都符合Freundlich 之等溫吸附模式；它們對鉻離子的吸附經由Freundlich 之等溫吸附模式計算後所得到的n值分別為2.29、1.70及1.20，也就是都屬於有利性的吸附。
由上可知：奈米鈦酸鋇具有些許的光催化特性，且對重金屬吸附的效果非常好。我們認為若是可以深入開發此礦物，它是具有潛力應用於環境汙染整治上的。

In recent years, environmental issues have become increasingly more important. Therefore, it is very important to determine an effective way to solve environmental problems. The perovskite minerals have the catalytic or photocatalytic properties, thus they own the ability of self-cleaning and photodegradation, e.g. the LaCrO3 and LaNiO3 can photocatalyze the CO or NOx gas. Additionally, the nano-perovskites can adsorb heavy metals due to its large specific surface area. In this study, nanoparticles with perovskite structure (nano-SrTiO3 and nano-BaTiO3) are synthesized via a co-precipitation method. The photocatalytic activity of nano-BaTiO3 (nano-BTO) is superior to that of nano-SrTiO3 (nano-STO), therefore, we try to adjust the synthetic parameters to fabricate different particle sizes of nano-BTO. Afterward their photocatalytic properties and Cu2+/Cr6+ adsorption characteristics are investigated.
From the XRD pattern, the nano-STO and nano-BTO have a cubic perovskite structure with a polycrystalline phase. The particle size ranges around 60~100 nm for nano-STO; 25, 75 (65~85), and 95 (80~110) nm for different particle sizes of nano-BTO, which is named BTO25, BTO75, and BTO95. The band gap, measured by UV-Vis spectrometer, is 3.43, 3.38, 3.37, and 3.39 for nano-STO, BTO25, BTO75, and BTO95, respectively. Moreover, the specific surface area is 9.98 m2/g for nano-STO; 36.32, 23.97, and 2.72 for BTO25, BTO75, and BTO95, respectively.
In the photocatalytic decomposition of methylene blue experiment, the photocatalytic activity of nano-BTO is better than that of nano-STO, and the photocatalytic efficiency is best for BTO75. As for the Cu2+ adsorption, the experimental data are well fitted to the pseudo-second-order equation except for BTO95 (pseudo-first-order). It suggests that the Langmuir isotherm is more adequate for Cu2+ adsorption onto nano-BTO. The maximum Cu(II) adsorption capacity is 28.49, 26.25, and 20.53 mg/g for BTO25, BTO75, and BTO-95, respectively. Further, the Cr6+ adsorption experimental data are well fitted to the pseudo-second-order equation. It also indicates that the Freundlich isotherm is more adequate for Cr6+ adsorption, and the Cr6+ adsorption onto nano-BTO is a favorable process.
Briefly, the nano-BTO exhibits some photocatalytic activity and possess a high adsorption capacity for copper and chromium ions. We believe that with continued development, this kind of nanomaterial can be employed in various environmental remediation applications.

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