Photocatalytic treatment of textile effluents by biosynthesized photo-smart catalyst: an eco-friendly and cost-effective approach

Worldwide, textile industry provides strong financial support for several countries because it provides more employment without any special training skills. Nevertheless, in the textile industry, various chemicals and large volumes of water are mainly used for the dyeing process and discharged effluents are toxic to living organisms if released without treatment. We have prepared an efficient photocatalyst carbon quantum dots (CQDs) from Spirulina platensis by microwave-assisted method. The powder form of CQDs is distributed in 10 nm in size studied by transmission electron microscope (TEM) and atomic force microscope (AFM). An optical and functional properties of CQDs were examined by photoluminescence (PL) spectrophotometer, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). It also exhibits a strong cyan blue fluorescence under UV transilluminator. Scavenging activity of CQDs was studied by 2,2-diphenylpicrylhydrazyl (DPPH) assay. 1 mg/mL of CQDs effectively degraded textile effluents under optimized conditions. The process of degradation and degraded molecules were analysed by gas chromatography/mass spectrometry (GCMS) and physico-chemical parameters such as biological oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) for treated water in order to check the quality. Finally, CQDs were removed from treated water by using activated carbon as an adsorbent. Non-toxicity of photocatalyst was proved by acute toxicity study using zebrafish as a research model. Graphical abstract