Mono mill pulverisette 6

The collected WTRs were transported from drinking water treatment plant (Alexandria, Egypt) to the laboratory. The bulk WTRs was mechanically ground using a stainless steel hammer mill, passed into a 0.51 µm sieve to obtain the WTRs powder (Fig. 1).The WTR powder (15 g) was ground to the desired nanoscale following the method of Elkhatib et al.^{12 (link)} by using Fritsch Planetary Mono Mill Pulverisette 6 classic line equipped with 80-ml stainless steel grinding bowl and 150 g of 1 mm steel grinding balls (10). The milling operation was conducted by alternating 10 min of milling with 5 min of rest to avoid excessive heat. The nanostructured WTR (nWTR) carrier was stored in ziploc polyethylene bags until further use. Sizes, shape, surface morphology of nWTRs were explored by TEM (H-7650, Hitachi, Japan). The crystallography phase of nWTRs was characterized through X-ray diffractogram, XRD (Bruker D2 Phaser diffractometer) and the diffractogram was recorded in the 2θ range = 0–100°. The surface chemical structure of the produced samples was evaluated by X-ray photoelectron spectroscopy (XPS).Figure 1

Schematic diagram of synthesis steps of nano- enabled fertilizers (NEF) based water treatment residuals nanoparticles (nWTR).

A pure OMC reference sample was prepared using a strategy reported by our team previously [29 (link)], which was a modified procedure adopted from the literature [7 (link)]. OMCs with well-dispersed metal nanoparticles were synthesized by adding metal salts at the right moment during the synthesis of OMC. Briefly, 1 g of Pluronic F127 and 2 mL of distilled water were initially milled for 5 min with a rotation speed of 500 rpm in a Planetary Mono Mill PULVERISETTE 6 classic line, ball milling machine (Fritsch, Bahnhofstraße, Germany). The device was equipped with a 45 mL ceramic milling bowl and 8 stainless, ceramic balls of diameter 1 cm. Next, a certain amount of metal salt was added, and milling was maintained for an additional 10 min. Afterward, 2 g of mimosa tannin was added, and the mixing was continued for 1 h. A uniform and easy-to-handle paste-like material (easily detaches from bowl and balls just in one tight piece) was directly transferred to a quartz boat and carbonized directly at 800 °C for 1 h under flowing nitrogen, a heating rate was 2 °C·min⁻¹. The as-obtained sample was cooled down naturally under flowing nitrogen and was then immersed in a small amount of ethanol-distilled water (1:1) solution; afterward, it was rinsed with water and dried at 80 °C.