Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite

Abstract

Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C3N4-P25) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria.

Alginate-Graphene Oxide Biocomposite Sorbent for Rapid and Selective Extraction of Non-Steroidal Anti-Inflammatory Drugs Using Micro-Solid Phase Extraction

“…2 shows the linear plot of Alg/GO adsorption/desorption isotherms. It specifies that Alg/GO relates to type 1V isotherms according to IUPAC classification, which belongs to mesoporous materials [22]. A hysteresis loop (type H3) also was observed and this type of desorption isotherm indicating the presence of slit-shaped pores resulting from the aggregation of plate-like particles [22][23].…”

“…It specifies that Alg/GO relates to type 1V isotherms according to IUPAC classification, which belongs to mesoporous materials [22]. A hysteresis loop (type H3) also was observed and this type of desorption isotherm indicating the presence of slit-shaped pores resulting from the aggregation of plate-like particles [22][23]. In addition, the rapid uptake starting from 0.8 to 1.0 of relative pressure (P/P 0 ) values, demonstrates the presence of numerous mesopore structures within the Alg/GO beads [20].…”

LP-UV-Nano MgO2 Pretreated Catalysis Followed by Small Bioreactor Platform Capsules Treatment for Superior Kinetic Degradation Performance of 17α-Ethynylestradiol

“…Li et al [30] investigated the combined photocatalysis-biodegradation of 2, 4, 5-trichlorophenol by a TiO 2 -coated biofilm composed of various bacterial strains of Ralstonia, Bradyrhizobium, Methylobacterium, Cupriavidus, and Pandoraea and found an enhanced degradation and mineralization of the pollutant under UV irradiation owing to photocatatalytic degradation and mineralization by TiO 2 , and biodegradation by the biofilm coated on a sponge carrier. Zhang et al [31] studied simultaneous photodegradation and biodegradation by g-C 3 N 4 -P25 and photosynthetic bacteria encapsulated in sodium-alginate beads, and observed significantly enhanced degradation and mineralization of the pollutants and reduced chemical oxygen demand of synthetic wastewater composed of textile dyes. Our future objective in this project is to coat MgO 2 on cellulose-based R. zopfii-containing capsules and study simultaneous photocatalysis and biodegradation of EE2 and various other pollutants in wastewater.…”

Isolation of a Microorganic Strain for the High Volume Degradation of Aniline Blue and Its Application in Natural Sewage Treatment

“…For the degradation of dyes in wastewater, a large number of microorganisms have now been screened, with numerous lab studies [52]. However, the composition of natural sewage is very complex [53], so it is necessary to explore whether screened microorganisms perform so well when treating natural wastewater. The typical aniline blue content in natural wastewater is 398.5 ± 2.85 mg/L.…”