Orion 5 star

Analytical methods described in Standard Methods (APHA, 2002 ) were used in this study as follows: Ammonium (NH₄⁺-N) (SM 4500-NH₃-D), Chloride (Cl⁻) (SM 4500 Cl-D) and fluoride (F⁻) (SM 4500 F-C) were tested potentiometrically using a Thermo Scientific Orion 5-Star portable multi-parameter and its corresponding probes (Thermo Specific Ion Selective Electrode, ISE Orion). Nitrate (NO₃⁻-N) (SM 4500-NO₃^--B), Phosphate (PO₄^3--P) (SM 4500-P-B), Chemical oxygen demand (COD) (Total and Soluble COD) (SM 5520-B) and Sulphide (S^2-) (SM 4500 S2-D) were measured using a visible spectrophotometer (Thermo Scientific Inc. GENESYS 30. United States). Likewise, Total Kjeldahl Nitrogen (TKN) (ISO 5663-1984, EPA 351.3 and AOAC 973.48) was measured colorimetrically using a SpeedDigester K-436 and Kjeldahl K-360 sampling system. Sulphate (SO₄^2-) (SM 426-C) and Total suspended solids (TSS) (SM 2540-D) were tested gravimetrically using glass microfiber filters (Whatman Grade 934-AH). Biochemical oxygen demand (BOD₅) (SM 5219 B) was measured in a 5-day period using the OxyTop system.

To ensure that target selection CO₂ levels were correct, the seawater carbonate buffer system was analysed in the experimental bottles periodically throughout the entire experiment, including at each sampling point. pH was measured using a Orion 5 STAR pH meter (Thermo Fisher Scientific) with a combined glass electrode. The metre was calibrated with National Bureau of Standards buffer solutions of pH 4, 7 and 10. Dissolved inorganic carbon was measured with CO₂ coulometry (model CM 140, UIC). The partial pressure of CO₂ in the samples was calculated from the measured pH and dissolved inorganic carbon values using CO₂SYS software7 8 11 . Because pCO₂ equilibrium was closely controlled using continuous bubbling, photosynthesis and respiration had minimal effects on the seawater carbonate system and measured pCO₂ was always within ∼5% of the two target values.

An Orion Conductivity Cell 913005MD with an epoxy/graphite electrode and a Thermo Orion 5 Star multiparameter instrument with a cell constant of 0.475 cm⁻¹ were used to perform conductivity measurements at a temperature of 25 °C [5 (link)].

A total of 0.2 g of a freshly collected leaves were incubated in 10 mL of double-distilled water at 40 °C for 30 min, then the electrical conductivity (C₁) of the solution was recorded using an electrical conductivity meter (Orion 5 Star, Thermo Fisher Scientific, Waltham, MA, USA). In another test tube, the second electrical conductivity (C₂) was recorded after 10 min incubation at 100 °C. The MSI was calculated using the following formula [52 (link)]: MSI (%) = [1 − (C₁/C₂)] × 100.

The collection of wastewater samples was performed following the methodology described by the Standard Methods for the Examination of Water and Wastewater section 1060 B (APHA, 2002 ). Flow values were measured in advance every 30 min to obtain a plot of volumetric flow as a function of time. This information was utilized to establish the relative proportions of wastewater that was collected every 30 min for 8 h to reach a total volume of 1 L. Then, three composite samples of domestic wastewater were collected from the discharge point at Universidad San Francisco de Quito (Quito, Ecuador) from October 2018 to January 2019. Composite samples were generated by collecting individual samples every 30 min, for 8 h, in volumes proportional to the flow of the discharge point. Samples were cumulatively collected in 1 L amber glass bottles that were transported to and stored in cool conditions at the Laboratory of Environmental Engineering at Universidad San Francisco de Quito (LIA-USFQ). In addition to volumetric flow, physical parameters like dissolved oxygen (DO) and temperature (T) (SM 4500-O A), pH (SM 4500 H⁺ B), and electrical conductivity (EC) (SM 2510) were measured in situ using a Thermo Scientific Orion 5-Star portable multi-parameter (Thermo Specific Electrode, Orion).

The simulated body fluid (SBF) was freshly prepared following the standard protocol [20 (link)] using analytical grade chemicals (Merck, India) to explore the in vitro bioactivity of the glass samples. The pH value of SBF was 7.4, which is equivalent to that of human blood plasma. From the prepared nanobioactive glass powders (NBG, SNBG, and NNBG), 250 mg was made as pellet using hydraulic pellet maker. The pellets were then immersed separately in 50 mL SBF and incubated at 37°C for 21 days. The ionic changes in the SBF were measured regularly using a pH meter (Orion 5-Star; Thermo Scientific, USA) at an interval of 24 h. After 21 days of immersion, the pellets were removed from the SBF, gently washed with distilled water, and then dried in hot-air oven. The weight loss percentage of sample was calculated according to the following equation:
$\begin{array}{c}\text{Weight}\mathrm{\hspace{0.17em}\hspace{0.17em}}\text{loss}\mathrm{\hspace{0.17em}\hspace{0.17em}}\left(\%\right)=\frac{W_0-W_t}{W_0}\times \mathrm{100},\end{array}$
where W₀ is the initial weight of the sample and W_t is the weight of the sample measured at time t after drying. The above-mentioned experimental procedure was repeated for all samples. After completing the SBF studies, all the prepared pellets were dried at 60°C. The characterisation studies, such as XRD, FTIR, and SEM analysis, were carried out for all samples (NBG, SNBG, and NNBG) to reveal the formation of HAp layer on the glass surface.

Approximately 300 g of the topsoil (0–15 cm) was collected from each treatment and selected soil properties were determined as follows: soil pH (1:5 method) using an electrode (Orion 5 Star, Thermo Scientific, Beverly, MA, USA), soil organic carbon content using the chromic acid oxidation method (Walkley–Black method), NH₄⁺, NO₂₋, NO₃₋, and available silicon using the colorimetric method, available silicate (SiO₄⁴⁻) by the 1 N sodium acetate method, and available phosphorus (P₂O₅) using the Bray No. 1 method. Exchangeable cations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) extracted by 1 N ammonium acetate were determined by inductively coupled plasma optical emission spectroscopy (730 Series, Agilent, Santa Clara, CA, USA).