Biochars are currently proposed as soil amendments or sorbent materials. There is an extensive scientific literature that deals with biochars originating from different raw materials. However, a holistic physicochemical characterization with simple analytical techniques is needed to provide insights on the characteristics of the biochars produced from malt spent rootlets (MSRs) and how they vary using different pyrolysis temperatures. This way, their properties can be fully understood, and they can be used for commercial purposes more effectively. Initially, the texture of the biochars were visualized by SEM and was quantified by the adsorption/desorption of nitrogen and the Brunauer, Emmett, and Teller (BET) equation. Additionally, the moisture content, the ash content and the pH of each sample were measured. Furthermore, the electrical conductivity of each sample was measured. Different techniques were used to determine the properties of carbon and of the surface functional groups (Total Carbon, XRD, ATR-FTIR) and leachable organic matter. Also, sorption of the methylene blue dye solution has been studied, which is an indication of mesopores for each biochar. Molasses number was also determined, as this is an indicator of macropores. Finally, the chlorine removal rate was determined for each type of biochar. The experiments marked that the change in mass of biochars has stopped after three hours at 50 °C in the drying oven. The measured moisture content ranged from 6 to 11%. The specific surface area of our materials, calculated through the BET equation, for low temperature biochars (e.g., 28 m²/g, at 350 °C), is much lower than that of high temperature pyrolyzed biochar (e.g., 286 m²/g, at 850 °C). The pH value ranged from 7 to 10. The electrical conductivity values of samples ranged from 800 μS/cm to 2.55 mS/cm, and these decreased during the measurement after the second wash with deionized water. Crystallinity increased with increasing pyrolysis temperature whereas the number of functional groups decreased. MSR biochars produced at temperatures equal or higher than 750 °C demonstrate different characteristics to the ones produced at lower temperatures.

The control of calcium carbonate formation is of high importance for a wide range of applications in the pharmaceutical industry and membrane processes as well as in the oil and gas industry. Herein, for the first time, the effect of monoethylene glycol (MEG) on the formation of calcium carbonate (CaCO₃) crystals from supersaturated solutions flowing through microchannels (volume 0.36 mL) of varying wettability was investigated. The use of microdevices enabled the observation of the scaling phenomenon in the early stages. Solutions supersaturated with respect to calcite, containing MEG (10, 20, and 30% v/v), were injected into the microchannel under a constant total flow rate and under laminar flow conditions (Re = 0.052). The growth of calcium carbonate crystals was monitored by video recording. The effect of the wettability on crystal formation was tested using glass and silane-coated microchips. The microchannel walls were wet and neutral-wet by the supersaturated solutions with a low MEG concentration. In the presence of a high MEG concentration in the supersaturated solutions, the walls of both types of microchips were neutral-wet. The results showed that the addition of MEG at a concentration of 10% v/v in the supersaturated solutions decreased the time of observation of the first crystal, favored secondary nucleation, and in general decreased the crystal growth rates. Raman spectroscopy identified the formation of aragonite in most cases, while as SR values increased, the formation of aragonite aggregates was favored. Further increases of the MEG concentration in the supersaturated solutions to 20% v/v, at low supersaturation ratio (SR) values, favored the formation of amorphous calcium carbonate (ACC) while at higher SR values aragonite crystals and aragonite aggregates formed. Further increases in the MEG concentration in the supersaturated solutions up to 30% v/v completely inhibited the nucleation and crystal growth of calcium carbonate.