NOx photocatalytic degradation on active concrete road surface — from experiment to real-scale application

The use of titanium dioxide (TiO2) as a photocatalyst in concrete pavements has received considerable attention in recent years due to its ability to decontaminate via photocatalytic processes. The objective of this study is to assess the effectiveness of activated concrete road in the degradation of nitrogen oxides (NOx). We have used a TiO2 and activated carbon (AC) permeable spray solution to coat concrete to assess its NOx purifying ability. A number of experiments were undertaken to ascertain the conditions that affect NOx purification. Indoor simulation experiments with active concrete road at optimum conditions show that it has good purification ability, self-regeneration and repetition ability, with a minimum decontamination rate for NO and NO2 of 37.4% and 25.84%, respectively. Outdoor experiments show that the photodegradation of NOx is related to light intensity and temperature. As the light intensity increases the reaction rate increases, and conversely as temperature increases the reaction rate decreases.

Graphical abstractThe cover picture shows mechanism of photocatalytic NOx oxidation on active concrete road. First, TiO2 and activated carbon (AC) are used to make spay solution which has permeability and purifying ability to NOx on concrete road surface. Successively, in reaction process, AC may effectively adsorb higher concentration of NO2 on road surface. Simultaneity, under UV illumination, NOx can be photo-oxidized to HNO3 by TiO2.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The manuscript has assessed the effectiveness of nitrogen oxides (NOx) degradation by permeable spray solution which is made of TiO2 and activated carbon. ► In indoor experiment, permeable spray solution which is similar to water ensures better NOx degradation effect when road surface is worn in 2–5 mm. ► In a real scale application, higher environment temperature declines more adsorption affinity of water compared with NOx on activated concrete road surface, which results in the growth of NOx decontamination rate. ► In the 1650 m2 experimental region, application cost of NOx degradation on concrete road is 9570 USD in a year.