Study on Degradation of 1,2,4-TrCB by Sugarcane Cellulose-TiO2 Carrier in an Intimate Coupling of Photocatalysis and Biodegradation System.

1,2,4 trichlorobenzene (1,2,4-TrCB) is a persistent organic pollutant with chemical stability, biological toxicity, and durability, which has a significant adverse impact on the ecological environment and human health. In order to solve the pollution problem, bagasse cellulose is used as the basic framework and nano TiO2 is used as the photocatalyst to prepare composite carriers with excellent performance. Based on this, an intimate coupling of photocatalysis and biodegradation (ICPB) system combining photocatalysis and microorganisms is constructed. We use the combined technology for the first time to deal with the pollution problem of 1,2,4-TrCB. The biofilm in the composite carrier can decompose the photocatalytic products so that the removal rate of 1,2,4-TrCB is 68.01%, which is 14.81% higher than those of biodegradation or photocatalysis alone, and the mineralization rate is 50.30%, which is 11.50% higher than that of photocatalysis alone. The degradation pathways and mechanisms of 1,2,4-TrCB are explored, which provide a theoretical basis and potential application for the efficient degradation of 1,2,4-TrCB and other refractory organics by the ICPB system.

A Cellulose-Type Carrier for Intimate Coupling Photocatalysis and Biodegradation.

Intimate coupling photocatalysis and biodegradation treatment technology is an emerging technology in the treatment of refractory organic matter, and the carrier plays an important role in this technology. In this paper, sugarcane cellulose was used as the basic skeleton, absorbent cotton was used as a reinforcing agent, anhydrous sodium sulfate was used as a pore-forming agent to prepare a cellulose porous support with good photocatalytic performance, and nano-TiO2 was loaded onto it by a low-temperature bonding method. The results showed that the optimal preparation conditions of cellulose carriers were: cellulose mass fraction 1.0%; absorbent cotton 0.6 g; and Na2SO4 60 g. The SEM, EDS and XPS characterization further indicated that the nano-TiO2 was uniformly loaded onto the cellulose support. The degradation experiments of Rhodamine B showed that the nano-TiO2-loaded composite supports had good photocatalytic performance. The degradation rate of 1,2,4-trichlorobenzene was more than 92% after 6 cycles, and the experiment of adhering a large number of microorganisms on the carriers before and after the reaction showed that the cellulose-based carriers obtained the required photocatalytic performance and stability, which is a good cellulose porous carrier.

Coupling of photocatalysis and biological treatment for elemental chlorine free bleaching wastewater: Application of factorial design methodology.

In this study, the visible-light-induced intimately coupled photocatalysis and biodegradation (ICPB) technology was fabricated using the TiO2/bagasse cellulose composite as the carrier and Phanerochaete mixed activated sludge as the biological source. The ICPB degradation effect of elemental chlorine free (ECF) bleaching wastewater was evaluated via the response surface design. Then, the wastewater was characterized, including absorbable organic halogen (AOX), dissolved organic carbon (DOC), chemical oxygen demand (COD), chroma, pH, suspended solids, and the organic compound changes in wastewater were analyzed by fourier transform infrared spectroscopy (FT-IR). Under the optimal conditions of pH 7, carrier filling rate of 5%, aeration rate of 2 L/min, and reaction time of 7 h, the degradation efficiencies of AOX, COD, and DOC were 95%, 91%, and 82%, respectively. The X-ray photoelectron spectroscopy (XPS) results of the ICPB carrier after the reaction were almost identical to those before the reaction. The biomass and its activity on the ICPB system were analyzed by the dominant bacteria during degradation (Curaneotrichosporon, Paenibacillus, Cellulonas, Phanerochaete, Dechlorobacter, Rhodotorula, Sphingobacterium, and Ruminiclostridium), which had a good degradation effect on wastewater. This study affords a novel method for the degradation of ECF bleaching wastewater and a new idea for ICPB technology optimization.

Degradation of chlorine dioxide bleaching wastewater and response of bacterial community in the intimately coupled system of visible-light photocatalysis and biodegradation.

Intimate coupling of visible-light photocatalysis and biodegradation (ICPB) offers potential for degrading chlorine dioxide bleaching wastewater. In this study, we reported a TiO2-coated sponge biofilm carrier with significant adhesion of TiO2 and the ability to accumulate biomass in its interior. Four mechanisms possibly acting in ICPB were tested separately: adsorption of chlorine dioxide bleaching wastewater to the carrier, photolysis, photocatalysis, and biodegradation by the biofilm inside the carrier. The carrier had an adsorption capacity of 17% and 16% for CODcr and AOX, respectively, in the wastewater. The photodegradation rate of wastewater was very low and could be ignored. Both biodegradation (AOX 30.1%, CODcr 33.8%, DOC 26.2%) and photocatalysis (AOX 65.1%, CODcr 71.2%, DOC 62.3%) possessed a certain degradation efficiency of wastewater. However, the removal rate of AOX, CODcr, and DOC in wastewater treatment by protocol ICPB reached 80.3%, 90.5%, and 86.7%. FT-IR and GC-MS analysis showed that the ICPB system had photocatalytic activity on the surface of the porous carrier in vitro, which could transform organic into small molecules for microbial utilization or complete mineralization. Moreover, the biofilm in the interior of the TiO2-coated sponge carrier could mineralize the photocatalytic products, which enhanced the removal of AOX, CODcr, and DOC by more than 15.2%, 20.0%, and 24.0%, respectively. The biofilm in the carrier of the ICPB system evolved, enriched in Proteobacteria, Chloroflexi, Bacteroidetes, and Actinobacteria, microorganisms known to play active roles in the biodegradation of papermaking wastewater.

Preparation and Photocatalytic Properties of a Bagasse Cellulose-Supported Nano-TiO2 Photocatalytic-Coupled Microbial Carrier.

Intimate coupling of photocatalysis and biodegradation (ICPB) has shown promise in removing unwanted organic compounds from water. In this study, bagasse cellulose titanium dioxide composite carrier (SBC-TiO2) was prepared by low-temperature foaming methods. The optimum preparation conditions, material characterization and photocatalytic performance of the composite carrier were then explored. By conducting a single factor test, we found that bagasse cellulose with a mass fraction of 4%, a polyvinyl alcohol solution (PVA) with a mass fraction of 5% and 20 g of a pore-forming agent were optimum conditions for the composite carrier. Under these conditions, good wet density, porosity, water absorption and retention could be realized. Scanning electron microscopy (SEM) results showed that the composite carrier exhibited good biologic adhesion. X-ray spectroscopy (EDS) results confirmed the successful incorporation of nano-TiO2 dioxide into the composite carrier. When the mass concentration of methylene blue (MB) was 10 mg L-1 at 200 mL, 2 g of the composite carrier was added and the initial pH value of the reaction was maintained at 6, the catalytic effect was best under these conditions and the degradation rate reached 78.91% after 6 h. The method of preparing the composite carrier can aid in the degradation of hard-to-degrade organic compounds via ICPB. These results provide a solid platform for technical research and development in the field of wastewater treatment.