The photocatalytic degradation of propyl paraben (PP) over Al-doped TiO₂ suspensions under simulated solar radiation was investigated. The catalysts were prepared by a co-precipitation method with the dopant content varying from 0.04 to 2 wt%. The catalyst with 0.04 wt% dopant was more effective than the rest, presumably due to a more efficient separation of the photogenerated charges associated with a greater crystallite size. Subsequent experiments with this catalyst showed that the rate of PP degradation (i) generally increased with increasing catalyst concentration in the range 125–1000 mg/L, and decreasing PP concentration (in the range 210–1687 μg/L), and (ii) was impeded at alkaline conditions (pH range 3–9). Moreover, degradation in pure water was always faster than in actual (i.e. bottled water, treated wastewater, surface water) or synthetic (i.e. pure water spiked with humic acid, t-butanol, chloride and bicarbonate ions) water matrices, pinpointing the competitive behavior of non-target water constituents. Conversely, the addition of persulfate had a beneficial effect on the rate of degradation since it acted both as electron acceptor and a source of extra sulfate radicals.

Al掺杂TiO _2上对羟基苯甲酸丙酯（PP）的光催化降解。研究了模拟太阳辐射下的悬浮液。通过共沉淀法制备催化剂，其中掺杂剂含量为0.04至2重量％。具有0.04 wt％掺杂剂的催化剂比其余催化剂更有效，大概是由于与更大的微晶尺寸相关的光生电荷的更有效分离。随后对该催化剂的实验表明，PP降解速率（i）通常随催化剂浓度在125–1000 mg / L范围内增加和PP浓度降低（210–1687μg/ L范围内）而增加，以及（ii ）在碱性条件（pH范围3–9）下被阻止。此外，纯净水的降解速度总是比实际水（即瓶装水，经处理的废水，地表水）或合成水（即掺有腐殖酸，叔丁醇，氯离子和碳酸氢根离子）的水基质，指出了非目标水成分的竞争行为。相反，过硫酸盐的添加对降解速率有有益的影响，因为它既充当电子受体又充当额外硫酸根的来源。