Multiwave pro

MOS was prepared by degradation assisted with microwave treatment. In a typical procedure, PM solution (50 mg/mL, pH 7–8) was treated at 120 °C for 20 min (Multiwave PRO, Anton-Paar, Graz, Austria). After decolorization with activated carbon, filtration, precipitation with alcohol, centrifugation, rotary vacuum evaporation, and lyophilization of the hydrolysate, crude MOS were obtained. The crude MOS was redissolved in distilled water, precipitated multiple times with alcohol, and centrifuged, and then the supernatant was lyophilized. The obtained MOS was dissolved in water and subject to isolation with an ultrafiltration centrifuge tube (3 KDa). The filtrate was discarded, and the retentate was collected and lyophilized to obtain the targeted MOS.

The total hardness and concentration of Ca²⁺ and Mg²⁺ were determined via the EDTA titration method [17 (link)]. Particle size was determined via the ASTM screening method [18 (link)]. The pH value of the water was measured using both an online and real-time pH meter (HACH sc200) as well as a handheld portable pH meter (HACH HQ11d). The composition of the particles emitted from the system was characterized using an inductively coupled plasma optical emission spectrometer (Optima 8000, Perkin Elmer), an electronic balance (ME104/02, Mettler Toledo), and a microwave digestion instrument (Multiwave PRO, Anton-Paar). A scale-inhibition tester [14 ] and a ZJ-type corrosion rate tester [16 ] were used to measure scale inhibition.

For the synthesis of iron oxide (Fe₂O₃) on
the VACNT structures, a published protocol for porous α-Fe₂O₃ nanosheets is modified for the use as a microwave-assisted
synthesis.^{52 (link)} About 2 mM of iron(III) sulfate
hydrate (Fe₂(SO₄)₃·H₂O, 244.98 g/mol, Fisher) and 8 mM of urea are dissolved in 50 mL
of ethylene glycol (EG, 62.07 g/mol, Fluka). Polyvinylpyrrolidone
(0.1 g) (PVP, K30, 40 000 g/mol, Fluka) is added to the solution.
After stirring for 10 min, the solution is filled into Teflon liners
for the microwave reactor (Multiwave Pro, Anton Paar). The VACNT structures
on the Si-wafer chips are treated with air plasma for 10 min to increase
the number of oxygen-containing surface groups and then slowly put
into the solution. The liners are put into the microwave and heated
to 160 °C for 5 h. Afterward, the solution is filtered using
vacuum filtration and the CNT structure is washed multiple times with
DI water. The filtered particles and the coated structure are dried
at 80 °C overnight.

After charge/discharge cycling, the coin cells were disassembled, the electrodes washed four times using 0.5 mL dimethyl carbonate (DMC, ≥99%, Sigma-Aldrich) followed by a drying procedure under reduced pressure at 60 °C. The separators were centrifuged at 8500 rpm using a Galaxy 5D (VWR LLC) to collect parts of the electrolyte for further analyses.
For the ICP-MS measurements of the aged electrodes, the samples were dissolved. This was done by microwave-assisted acid digestion using a Multiwave Pro (Anton Paar GmbH). Polytetrafluoroethylene (PTFE) liner were filled each with 3 mL nitric acid (65 vol%, Suprapur®, Merck KGaA) and hydrochloric acid (32 vol%, Suprapur®, Merck KGaA) followed by a 7 min power ramp to 1400 W, a hold period of 42 min and a cool down step until 55 °C was reached. Afterward, the samples were diluted using deionized water (2 μg L⁻¹ TOC, 25 MΩ, MilliQ, Merck KGaA).

Microwave-assisted acidic digestion of AuNP samples was conducted in the microwave Multiwave Pro (Anton Paar, Germany) which is equipped with two standard magnetrons of 850 W able to deliver a microwave power up to 1500 W in an unpulsed mode over the full power range. The applied microwave energy is controlled by contactless sensors for internal temperature and vessel pressure and by IR sensor which is equipped with a temperature sensor, preventing overheating, and an IR sensor monitors the temperature of vessels. Rotor 24HVT50 was used with pressure vessels HVT50 made of PTFE-TFM. Briefly, samples were gradually defrosted from −80 °C → -20 °C → 4 °C → room temperature. Samples were transferred into vessels and were treated with HNO₃ 70% (0.6 mL, Sigma Adrich) and H₂O₂ 30% (0.3 mL, Merck). The volume was completed to 3 mL with millipore H₂O (0.3 mL). Samples were placed in the microwave and the mixture was irradiated at 100 °C (ramp for 10 min, hold 10 min) and further at 140 °C (ramp for 10 min, hold for 10 min) and finally cooled to 70 °C (ramp 12 min) with a maximum power of 600 W. Samples was then transferred into 15 mL falcon tubes, and each vessel was rinsed with millipore H₂O (0.5 mL). Finally samples were completed with millipore H₂O, if necessary, to a final volume of 3.5 mL.

The magnetic clinoptilolite (MAG-CLI) was prepared following the slightly modified procedure described by Iskandar et al. [43 ]. Briefly, the aqueous solutions of FeCl₃·6H₂O (0.4 M) and FeSO₄·7H₂O (0.2 M) in the molar ratio of 1:2 were mixed properly with the CLI water suspension at room temperature. Subsequently, the aqueous solution of NaOH (2 M) was added dropwise to the prepared suspension until the pH reached 10. The formed black suspension was transferred to four Teflon vessels and MW-irradiated (Microwave Reaction System SOLV, Multiwave PRO, Anton-Paar GmbH, Graz, Austria) at 200 °C for 5 min under high stirring. The inner pressure and temperature were monitored during the synthesis process. The synthesized dark brown precipitate after the MW-assisted co-precipitation reaction was separated from the suspension by centrifugation and washed several times with deionized water until showing a negative reaction to the chloride ions. Finally, the obtained MAG-CLI was dried in the oven at 100 °C until reaching a constant mass. The sample was left to cool to room temperature before its further use.

The magnetic nanoparticles (MAG) were prepared according to the already reported literature procedure [42 (link)]. Aqueous solutions of two iron salts—FeCl₃·6H₂O (0.4 M) and FeSO₄·7H₂O (0.2 M)—in a molar ratio of 2:1 were mixed properly. Subsequently, the water solution of NaOH (2 M) was added to the iron salt solution, and the solution was microwave (MW)-irradiated (Microwave Reaction System SOLV, Multiwave PRO, Anton-Paar GmbH, Graz, Austria). The obtained black precipitate (MAG) was separated from the liquid phase, washed several times with deionized water, and dried until reaching a constant mass.