The formation of Au NPs was monitored by UV–vis spectra of the reaction mixture from 210 to 800 nm. Primary study of nanoparticle shape and size was carried out using an SPI-3800N atomic force microscope with SPA 400 soundproof housing sample holder connected to an imaging system (Seiko Instruments, Chiba, Japan). Five microlitres was taken from the reaction mixture and placed on the glass grid and dried at room temperature. The images were obtained using SPIWin (3800N) ver. 3.02J (Wyandotte, MI, USA). Morphology and grain size of these nanoparticles were BTSA1 nmr analysed using a Hitachi H-7100 transmission electron microscope. Two microlitres was taken from the two reaction mixtures and placed on carbon-coated copper grids

and Napabucasin cell line dried at room MG-132 concentration temperature. The transmission electron micrographs and the SAED patterns were recorded at an acceleration voltage of 100 kV. The images were analysed using the ImageJ 1.43M software. FT-IR analysis was done using Jasco FT/IR-680 plus (Easton, MD, USA) coupled to a high-performance computer. The samples (100 μL) were placed over the ATR analyser, and the resulting spectra were analysed using Spectra Manager ver. 1.06.02. Zeta potential measurements were performed using the Malvern Zetasizer Nano ZS model ZEN3600 (Malvern, UK) equipped with a standard

633-nm laser. Confirmatory study of resulting Au NPs was done by XRD using a Rigaku RINT-TTR diffractometer (Tokyo, Japan) equipped with a parallel incident beam (Göbel mirror) and a vertical θ-θ goniometer. Samples were placed directly on the sample holder. The X-ray many diffractometer was operated at 50 kV and 300 mA to generate CuKα radiation. The scan rate was set to 5° mil−1. Identification of the metallic gold was obtained from the JCPDS database. Preparation of biomass-supported Au nanocatalyst in 4-nitrophenol degradation The reduction of 4-NP by NaBH4 was studied as a model reaction to probe catalytic efficiency of a biomass-supported Au catalyst for heterogeneous systems. Under experimental conditions, reduction does not proceed at all simply with the addition of NaBH4 or biomass alone. However, in the presence of a biomass-supported Au catalyst, it proceeds to completion with formation of 4-aminophenol

(4-AP). To study the reaction in a quartz cuvette, 2.77 mL of water was mixed with 30 μL (10−2 M) of 4-NP solution and 200 μL of freshly prepared NaBH4 (10−1 M) was added. The Au NP reaction mixture along with the MBF was dried for 24 h at 90°C, and 5 mg of biomass-Au NP composite (size approximately 50 nm, 4.2 × 10−6 mol dm−3) was added to the above reaction mixture. A similar technique was used by Narayanan and Sakthivel [20] by coating fungal mycelia-coated Au NPs on glass beads. UV–vis spectra of the sample were recorded at every 2-min interval in the range of 200 to 600 nm. The rate constant of the reduction process was determined by measuring the change in absorbance of the initially observed peak at 400 nm, for the nitrophelate ion as the function of time.