Design Aspects of a Continuous Flow Photocatalytic Reactor and its Application to Degrade Methylene Blue and Textile Wastewater

Abstract

A continuous flow photocatalytic reactor was developed by combining the reaction kinetics and mass balance concept. The concept of cascade aerator was also considered in designing it as a stepped reactor. The reactor was used to investigate the photocatalytic degradation of methylene blue in aqueous solution by Ag + doped TiO 2 (2 g/L) under UV irradiation by 15 W UV lamps (254 nm). Methylene blue solution (20 ppm) was found to be decolorized by > 99, 97, 85 and 57 % under flow rates of 1, 1.5, 2 and 3 L/h, respectively after 120 minutes. The corresponding mineralization was > 80, 78, 75 and 54 %, respectively. At higher flow rates (Re number 208.2 and 415.5) > 99 % decolourization was achieved by recycling the solution 5 and 7 times with fresh doses of photocatalyst. At steady state, maintained by repeating the addition of photocatalyst at fixed time intervals, the dye solution could be decolourized continuously by > 99, 97 and 76 % at flow rates of 1, 2 and 3 L/h, respectively while the mineralization was > 82, 79 and 62 %, respectively. The reactor was also effectively used to mineralize textile wastewater collected from a textile mill in Kolkata. The mineralization was greater than 75, 73 and 64 % at flow rates of 1, 2 and 3 L/h, respectively after 120 minutes. The efficiency of the reactor depended upon the residence time of the contaminant in the reactor. At steady state, the design data simulated well with the corresponding experimental data.

Enhanced photocatalytic degradation of methylene blue using a novel counter-rotating disc reactor

“…The resulting removal percentages for the MB dye and COD were 95.12% and 64.25%, respectively, closely aligning with the predicted values. This removal efficiency was consistent with the results of other studies (Chakrabarti and Dutta, 2004;Ehrampoosh et al, 2011;Li et al, 2015;Sahoo et al, 2022).…”

“…Furthermore, the influence of the initial dye concentration on reducing COD removal efficiency intensifies with an increase in the number of stabilized layers. Sahoo et al (2022) utilized a photocatalytic reactor to investigate the removal of MB from textile wastewater, focusing on the relevant parameters. COD removal for MB at flow rates of 1, 1.5, 2, and 3 L per hour was 54%, 75%, 78%, and 80%, respectively, over 120 min.…”

Mesostructured Nonwovens with Supramolecular Tricycloquinazoline Nanofibers as Heterogenous Photocatalyst

“…In contrast to batch‐type processes, processes under continuous flow conditions have the advantage that larger quantities can be converted and a lower treatment time may be required. [ 35 ] Thus, we investigated the suitability of TCQ nanofiber/glass‐microfiber nonwovens as photocatalyst for degradation of the dye rhodamine B and the common antibiotic tetracycline in water under continuous flow conditions.…”

Water Challenges in South Asian Countries: A Focused Review on Emerging Nanomaterials and Technological Processes in Wastewater Treatment

“…To date, only limited research has been done by using real wastewater samples from textiles, rivers, etc. for water treatment purposes − due to the many logistic, environmental, and economic challenges. These issues need to be effectively addressed before successful implementation of TiO 2 /GO nanocomposites in real-world water treatment plants.…”