Synthesis of zinc chloride activated eco-friendly nano-adsorbent (activated carbon) from food waste for removal of pollutant from biodiesel wash water

Food waste has been a complex component added to municipal solid waste, making it a major reason for the evolution of greenhouse gases, foul odour and a dwelling habitat for insects and microbes. Diversion of the mixed food waste (unsegregated) to useful materials (activated carbon) would have immense industrial significance. In this study, rice, vegetables, oil and spice (WCVR); mixed fruit peels including banana peel, pomegranate peel, orange peel and lemon peel (MFPW); plain rice (WCR) and mixed food waste (rice, dhal, vegetables, fruits, meat and bones) (MFW) were used. Food waste samples were heated at a temperature of 350 °C for 3 h in an incinerator and then activated with zinc chloride for 2 h in a muffle furnace maintained at 500–600 °C temperature. Zinc chloride activated carbon was characterized through X-ray diffraction, field emission scanning electron microscopy and fourier transform infrared spectroscopy. WCR carbon was the best-activated carbon, yielding nanomaterials with 2θ = 25.81, 31.76, 34.41 and 56.54, which was in accordance with the JCPDS card number. The MFW activated carbon reduced the biodiesel wash water pH from 10 to 6.5 making it suitable for recycling. Turbidity was reduced by 98.41%, chemical oxygen demand by 41.33%, oil and grease by 99.05% for MFW carbon. HIGHLIGHTS Biodiesel washwater was generated enormously during biodiesel synthesis.; Food waste was converted to activated carbon (AC) and activated with zinc chloride.; Synthesized AC had high intensity peaks at 31.9°, 34.5° and 36.5°.; 0.5 g AC reduced turbidity, COD, oil and grease by 98.41, 41.33 and 99.05%.