【摘要】：光催化技術(shù)具有能耗低、成本低、無(wú)二次污染等優(yōu)點(diǎn),使其得到了研究者的廣泛關(guān)注。然而現(xiàn)有的大部分光催化劑只能吸收紫外區(qū)域的高頻光子能量,而對(duì)可見(jiàn)光區(qū)域以內(nèi)的低頻光子能量不能有效利用,并且在光催化反應(yīng)過(guò)程中光生載流子容易二次復(fù)合。因此,擴(kuò)寬光催化劑的可見(jiàn)光響應(yīng)范圍、抑制光生載流子的復(fù)合,對(duì)提高材料的光催化性能具有實(shí)際意義。BiFeO_3是一種鈣鈦礦型、窄帶隙半導(dǎo)體材料,由于其具有良好的可見(jiàn)光催化活性,得到了人們的廣泛研究。本文以PEG-20000為分散劑,采用一步水熱法制備了純相BiFeO_3半導(dǎo)體材料。以BiFeO_3為主催化劑,合成了復(fù)合光催化劑—Ag/AgCl/BiFeO_3和Ag/RGO/BiFeO_3,研究了兩種復(fù)合光催化劑對(duì)模擬廢水的降解效果,并建立了其對(duì)羅丹明B的光催化動(dòng)力學(xué)模型。主要研究?jī)?nèi)容及結(jié)論如下:(1)以PEG-20000為分散劑,在溫度160℃,水熱反應(yīng)10h,制備了BiFeO_3光催化劑,采用XRD、SEM、EDS、UV-Vis DRS等手段對(duì)其相態(tài)、結(jié)構(gòu)、形貌、光吸收特性等進(jìn)行了表征分析。結(jié)果表明,在堿性條件下制備BiFeO_3結(jié)晶度較好,其微觀形貌尺寸大約35μm,微觀尺寸均勻,光吸收能力較強(qiáng)。(2)以BiFeO_3、RGO和AgNO_3為原料,采用水熱制備了Ag/RGO/BiFeO_3光催化劑;以BiFeO_3、AgCl為原料,在光照條件下合成了Ag/AgCl/BiFeO_3光催化劑。結(jié)果表明,在光照條件下,Ag/AgCl/BiFeO_3的光生載流子有兩種遷移方式,當(dāng)加入較少的AgCl時(shí),AgCl顯示的是直接帶隙,光催化反應(yīng)基本在BiFeO_3表面進(jìn)行;當(dāng)加入較多,AgCl時(shí)形成間接帶隙,光催化反應(yīng)在AgCl和BiFeO_3表面進(jìn)行,反應(yīng)活性位點(diǎn)相對(duì)于前者增多。分析發(fā)現(xiàn),在后一種物質(zhì)的光催化過(guò)程中,光電轉(zhuǎn)化效率明顯提高,光生電子-空穴對(duì)復(fù)合機(jī)率減少,載流子利用效率提高。(3)研究了Ag/RGO/BiFeO_3和Ag/AgCl/BiFeO_3光催化劑光催化降解染料廢水和含酚廢水的性能,結(jié)果表明Ag/RGO/BiFeO_3和Ag/AgCl/BiFeO_3對(duì)染料廢水和含酚廢水具有良好的光催化活性�；钚宰杂苫鶎�(shí)驗(yàn)表明,羥基自由基、超氧自由基、光生空穴對(duì)光催化反應(yīng)過(guò)程都有貢獻(xiàn),其中羥基自由基是主要活性物種。(4)建立了基于蘭格繆爾的Ag/RGO/BiFeO_3、Ag/AgCl/BiFeO_3表面吸附有機(jī)污染物的模型方程式,分別為1/Q_e=10.2429/c_e+0.42384和1/Q_e=10.5017/c_e+0.33483。建立了基于Langmuir-Hinshewood的Ag/RGO/BiFeO_3、Ag/AgCl/BiFeO_3光催化降解有機(jī)污染物的動(dòng)力學(xué)方程1/r0=32.5c_0+8.08和1/r_0=27.59/c_0+1.048。
[Abstract]:Photocatalytic technology has many advantages, such as low energy consumption, low cost and no secondary pollution. However, most photocatalysts can only absorb the high-frequency photon energy in the ultraviolet region, but the low-frequency photon energy in the visible region can not be used effectively, and photogenerated carriers are easy to recombine in the photocatalytic reaction. Therefore, broadening the range of visible light response of photocatalyst and restraining photogenerated carrier compounding is of practical significance to improve the photocatalytic performance of the materials. BiFeO3 is a perovskite-type, narrow-band gap semiconductor material. Because of its good visible light catalytic activity, it has been widely studied. In this paper, pure phase BiFeO_3 semiconductor materials were prepared by one step hydrothermal method with PEG-20000 as dispersant. Using BiFeO_3 as the main catalyst, the composite photocatalysts-Ag- / AgCl- / BiFeO3 and Ag- / RGO- BiFeO3 were synthesized. The degradation effect of two kinds of composite photocatalysts on simulated wastewater was studied, and the photocatalytic kinetic model of Rhodamine B was established. The main contents and conclusions are as follows: (1) BiFeO_3 photocatalyst was prepared at 160 鈩，

本文編號(hào)：2176204