A comprehensive appraisal on status and management of remediation of DBPs by TiO2 based-photocatalysts: Insights of technology, performance and energy efficiency

Optimization of ultrasound-electrocatalytic process for improving the quality of biological treatment effluent

Improving the quality of biologically treated effluent could encourage the reuse of wastewater. It is uncommon to use enhanced electrochemical oxidation techniques to improve effluent. Using hydrothermal reaction with complicated precipitation, the work generated FTO-TiO2/Ni anodes and analyzed them with the following methods: TEM, FESEM, EDS, elemental mapping, XRD, FTIR, and CV analysis. A 500 mL sono-electrocatalyst process reactor was used with central composite design in order to achieve the greatest decrease in COD. The reaction kinetics, synergistic effect of mechanisms, physicochemical properties of wastewater after the process, energy efficiency, and toxicity of wastewater were all investigated under ideal conditions. The anode electrode analyses indicate that the synthesis is sufficient. The quadratic model is noteworthy because of the P-value (0.0001) and the F-value (600.39). The correlation coefficients were much greater than the values obtained for the other model. The experimental settings were pH 7.1, 74.4 mA/cm2 DC power, 15 mW/cm2 applied USI, and a reaction time of 112 min (COD reduction = 81.5%). Chemical reactions follow first-order kinetics (R2 = 0.99). The synergistic coefficients for the pathways were 1.6 for COD, 2.2 for BOD5, and 1.5 for TOC. After 300 min, the energy efficiency was 1.07 kWh/m3, and the toxicity of the effluent was reduced to 5%. The above technique was shown to be a feasible advanced treatment that can improve effluent discharge, according to this study.

Real "zero energy consumption" for efficient antibiotics degradation by floating photocatalysis: modeling, degradation pathway and toxicity assessment

Floating photocatalysis is a real "zero energy consumption" and practicable green water treatment technology because of no need for reactor and pump, and direct contact with sunlight to produce more free radicals compared to traditional immersion photocatalysts. To realize "green" and "safe" practical application, efficiency for different water quality bodies and toxicity assessment of degradation products are key factors. In this work, an economic and efficient floating photocatalyst Bi doped P25-TiO2 (Bi@P25)/expanded perlite (EP), named BTEP was successfully constructed, exhibiting stronger visible light absorption and faster photogenerated carriers separation ability due to Bi doping and formation of Bi-O-Si bond. Ciprofloxacin (CIP) degradation efficiency (10 mg/L) in deionized water and three types of ambient water reached 97.8 % and 52.9 %-75.2 %, respectively, based on the major active species (h+ and •O2-). Three degradation pathways were determined and the reduced toxicity of most intermediates proved the process is green and safe. BTEP had strong adaptability over a wide pH range (3-9). The degradation efficiency is promoted by higher temperatures, while depressed by humic acid (HA) (still maintain over 65.3 % at 15 mg/L of HA). Moreover, the Random Forest model is the most suitable to achieve degradation efficiency prediction of different water parameters duo to the lowest root mean square error (RMSE) value (9.52) and the highest R2 value (0.9045). The BTEP based floating photocatalysis promotes the practical application of solar photocatalytic technology and realizes zero energy consumption to remove pollutants.

Fabrication and catalytic activity of TiO2/Fe3O4 and Fe3O4/β-cyclodextrin nanocatalysts for safe treatment of industrial wastewater

The rapid industrial growth has led to increased production of wastewater containing pollutants like heavy metals and organic compounds. These pollutants pose risks to human health and the environment if not properly treated. Engineered nanocatalyst materials (ENMs) are a burgeoning technology that show promise for treating industrial wastewater. Metal oxide ENMs, such as Fe3O4@β-cyclodextrin and Fe3O4@TiO2, have demonstrated efficient removal of heavy metals and methylene blue from wastewater. Fe3O4@TiO2 was found to be more effective than Fe3O4@β-cyclodextrin in removing these pollutants. The highest removal efficiencies were observed at a concentration of 40 mg/g and pH 8. Copper showed the highest removal efficiency (160.5 mg/g), followed by nickel (77.09 mg/g), lead (56.0 mg/g), and cadmium (46.05 mg/g). For methylene blue, the highest removal efficiency was also observed at a concentration of 40 mg/g and pH 8 (91.16 %). Lead (90.5 %), copper (90.48 %), nickel (83.34 %), and cadmium (77.58 %) were also efficiently removed. These findings highlight the potential of Fe3O4@TiO2 as a promising material for industrial wastewater treatment, offering cleaner and safer water for human health and the environment. ENMs have the potential to revolutionize wastewater treatment processes.

Activity and recyclability enhancement of pH-dependent Fe0@BC-mediated heterogeneous sodium percarbonate (SPC)-reducing agents (RA) system

Dyes pose great threats to the aquatic environment and human health. Fe0-based Fenton-like systems have been widely employed for the degradation of organic dyes. However, the regulation of degradability and recyclability was still unclear. In this study, Rhodamine B (RhB) was served as the model pollutant, hydroxylamine hydrochloride was selected as the RA, the natural photocatalysis system demonstrated stable operation. RA, as performance enhancement agent, was firstly reported in micro/nano-Zero-Valent Iron@Biochar (m/nZVI@BC) based SPC-RA system. Carrier size-fractionated m/nZVI@BC was fabricated by one-step carbothermal method. As a result, RA synergistically interacted with SPC, and the reaction time reduced from 15 min to 4 min. In the 0.010 g m/nZVI@BC-mediated SPC-RA system, over 95% of RhB (100 mg·L-1, 1041.667 mg·g-1) was successfully degraded. The maximum degradation ability could still exceed 1g·g-1 via 5 times repeated applications. Meanwhile, the loss of degradability, caused by halving SPC concentration could be compensated by RA dosage measurement. The entire degradation process was predominantly dominated by free radicals (•OH> 1O2> •O2-> •CO3-). Reactive oxidizing species (ROSs) were primarily excited by α-Fe0, Fe3C and N sites of biochar (BC). Light and BC carrier dedicated slight influence. These discoveries shed a light on the activity and recyclability regulation of catalytic material, aligning with the principles of green chemistry and cleaner production. This study demonstrates a novel approach to efficient management of solid waste disposal, reuse of waste biomass, advanced treatment of dye-containing wastewater, pollution control in aquatic environments.

A Comprehensive Review on Modification of Titanium Dioxide-Based Catalysts in Advanced Oxidation Processes for Water Treatment

It has become necessary to develop effective strategies to prevent and reduce water pollution as a result of the increase in dangerous pollutants in water reservoirs. Consequently, there is a need to design new catalyst materials to promote the efficiency of advanced oxidation processes (AOPs) in the field of wastewater treatment plant to ensure the mineralization of trace organic contaminants. A notable approach gaining attention involves the coupling of sulfate radicals-based AOPs to photocatalysis or electrocatalysis processes, aiming to achieve the complete removal of refractory contaminants into water and carbon dioxide. Titanium dioxide as metal oxide has received great attention for its catalytic application in water purification. TiO2 catalysts offer a multitude of advantages in AOPs. They are characterized by their high photocatalytic activity under both ultraviolet and visible light, making them environmentally friendly due to the absence of toxic byproducts during oxidation. Their versatility is remarkable, finding utility in various AOPs, from photocatalysis to photo-Fenton processes. TiO2's durability ensures long-lasting catalytic activity, which is crucial for continuous treatment processes, and their cost-effectiveness is particularly advantageous. Furthermore, their chemical stability allows it to withstand varying pH conditions. However, the large band gap energy and low electrical conductivity hinder the catalytic reaction effectiveness. This review aims to examine various approaches to enhance the catalytic performance of titanium dioxide, with the objective of enabling more efficient water purification methods.

Pressure-driven membrane filtration technology for terminal control of organic DBPs: A review

Disinfection by-products (DBPs), a series of undesired secondary contaminants formed during the disinfection processes, deteriorate water quality, threaten human health and endanger ecological safety. Membrane-filtration technologies are commonly used in the advanced water treatment and have shown a promising performance for removing trace contaminants. In order to gain a clearer understanding of the behavior of DBPs in membrane-filtration processes, this work dedicated to: (1) comprehensively reviewed the retention efficiency of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) for DBPs. (2) summarized the mechanisms involved size exclusion, electrostatic repulsion and adsorption in the membrane retention of DBPs. (3) In conjunction with principal component analysis, discussed the influence of various factors (such as the characteristics of membrane and DBPs, feed solution composition and operating conditions) on the removal efficiency. In general, the characteristics of the membranes (salt rejection, molecular weight cut-off, zeta potential, etc.) and DBPs (molecular size, electrical property, hydrophobicity, polarity, etc.) fundamentally determine the membrane-filtration performance on retaining DBPs, and the actual operating environmental factors (such as solute concentration, coexisting ions/NOMs, pH and transmembrane pressure) exert a positive/negative impact on performance to some extent. Current researches indicate that NF and RO can be effective in removing DBPs, and looking forward, we recommend that multiple factors should be taken into account that optimize the existed membrane-filtration technologies, rationalize the selection of membrane products, and develop novel membrane materials targeting the removal of DBPs.

Bromine Ion-Intercalated Layered Bi2WO6 as an Efficient Catalyst for Advanced Oxidation Processes in Tetracycline Pollutant Degradation Reaction

The visible-light-driven photocatalytic degradation of pharmaceutical pollutants in aquatic environments is a promising strategy for addressing water pollution problems. This work highlights the use of bromine-ion-doped layered Aurivillius oxide, Bi2WO6, to synergistically optimize the morphology and increase the formation of active sites on the photocatalyst's surface. The layered Bi2WO6 nanoplates were synthesized by a facile hydrothermal reaction in which bromine (Br-) ions were introduced by adding cetyltrimethylammonium bromide (CTAB)/tetrabutylammonium bromide (TBAB)/potassium bromide (KBr). The as-synthesized Bi2WO6 nanoplates displayed higher photocatalytic tetracycline degradation activity (~83.5%) than the Bi2WO6 microspheres (~48.2%), which were obtained without the addition of Br precursors in the reaction medium. The presence of Br- was verified experimentally, and the newly formed Bi2WO6 developed as nanoplates where the adsorbed Br- ions restricted the multilayer stacking. Considering the significant morphology change, increased specific surface area, and enhanced photocatalytic performance, using a synthesis approach mediated by Br- ions to design layered photocatalysts is expected to be a promising system for advancing water remediation.