Whatman filter paper no 42

Desorption experiments following the method of Han et al. [53 ] were undertaken to determine whether MPs could release previously sorbed phosphate and to compare desorption with that from soils. Solids from the initial adsorption experiments were collected on Whatman No. 42 filter paper and washed with 30 mL saturated NaCl to remove free P. Solids were then added to 30 mL of 0.10 M NaNO₃. The mixtures were shaken at 180 rpm for 24 h, filtered using Whatman No. 42 filter paper and finally the supernatants were analyzed using ICP-OES to determine P concentration in the solution.

A variety of CMC-CSAC adsorbents (5 g) previously prepared as previously stated was mixed with 50 mL cell-free lactic acid fermentation broth (pH 6). The mixture was stirred at room temperature for 150 min before filtering through Whatman filter paper No.42. The liquid portion was kept for analyses of metal ions and lactic acid concentration using atomic adsorption spectrophotometry (AAS), high performance liquid chromatography (HPLC), and ion chromatography (IC).
The optimal contact time was determined. Five g of CMC-CSAC adsorbent grafted with 2% CMC and 20% CA was mixed with 50 mL cell-free lactic acid fermentation broth at room temperature. The contact time was varied (0–24 h). Later, the mixture was filtered through Whatman filter paper No.42. The liquid portion was kept for analyses of metal ions and lactic acid. The effect of the initial pH of the fermentation broth and operating temperature on ion adsorption onto CMC-CSAC was studied. After harvesting, lactic acid fermentation broth had an initial pH of 6. The pH was adjusted to 2 by adding 10 M H₂SO₄. The adsorption capacity was also investigated by varying the ratio of lactic acid fermentation broth (L) to solid CMC-CSAC adsorbent (S) from 2.5 to 20.

N mineralization and nitrification were assessed by the modified anaerobic incubation method [27] . Briefly, fresh soil samples (5 g) were placed into a 200 mL plastic bottles, 10 mL deionized water was added to the bottles to thoroughly submerge the soil. The plastic bottles were sealed with stopper to avoid water evaporation during incubation, and placed in a constant temperature (40°C) incubator for 7 days. At the beginning of the incubation experiment, pre-incubation soil was sampled to measure the initial concentrations of NH₄⁺-N and NO₃⁻-N. After a week of incubation, the post-incubation soil samples were mixed with 40 mL of 2 M KCl using a 1: 8 soil: extractant (w/v) ratio, shaken for 30 min on a reciprocal shaker; then the extracts were filtered through prewashed Whatman no. 42 filter papers and supernatants were stored at −20°C until analysis of NH₄⁺-N and NO₃⁻-N concentrations. The NH₄⁺-N and NO₃⁻-N concentrations were separately measured by spectrophotometry using the ammonium indophenol blue method and the cadmium reduction method [28] . All concentrations of NH₄⁺-N and NO₃⁻-N were based on dry soil weight and expressed on a mg·g⁻¹ (DW). The N mineralization rate (N_min) was calculated as the changes in the inorganic N (NH₄⁺-N, NO₃⁻-N) content from time zero to 7 days. A similar formula was used to calculate N nitrification rate (N_nitri) [29] , [30] :

The soil extractable Se and S were determined using two different P solutions (0.016 M KH₂PO₄ (pH = 4.8) and 0.016 M P-buffer (NaH₂PO₄/Na₂HPO₄, pH = 7.5)). KH₂PO₄ is an established reagent for extracting plant-available S (Zhao and McGrath 1994 (link)). Due to the chemical similarity between SO₄²⁻ and SeO₄²⁻, the reagent is used to extract Se from soil (Stroud et al. 2010 ). The use of P-buffer in this study is a new attempt to investigate the effect of a different pH environment on Se sorption in the soil. A 5 g-DM soil sample was weighed into a 50 mL sample tube followed by adding 25 mL of one of the P solutions and extracted for 1 h at 25 °C. After extraction, the extracts were filtered through Whatman No.42 filter papers. The supernatants were acidified in 5% HNO₃ (v/v) before analysis of total Se and S in the extracts using ICP-OES or ICP-MS. The analysis of soil extractable P followed the method of Olsen et al. (1954 ).

All dried parts (including shoots and leaves) of each treatment were ground through a 40-mesh sieve to determine the tissue nutrient concentration in T. luteum subsp. gabesianum. Three samples of fine powder were made corresponding to the three fertilization treatments (ChF, INM, control) applied. Each sample was further divided into three subsamples of ca. 0.25 g each, and each subsample was disorganized by the method of wet oxidation using a triple acid mixture of H₂SO₄, HNO₃, and HClO₄ in a ratio of 5:1:1 at 80 °C until a transparent solution was obtained [53 ]. The digested samples were filtered using Whatman No. 42 filter papers and the filtrates were finally complemented with distilled water up to 50 mL. The solutions were analyzed for total P colorimetrically according to the Molybdenum Blue Method by using a Shimadzu spectrophotometer model UV-1201V [54 ]. The total concentrations of magnesium (Mg), potassium (K), calcium (Ca), sodium (Na), copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) were determined by atomic absorption spectroscopy (Perkin-Elmer Analyst 300). Acetylene gas was used as fuel and air as a supportive agent. An oxidizing flame was used in all cases. Furthermore, for the determination of N, three sub-samples of ca. 0.25g each of the powder were taken from each sample. Total N was determined by the Kjeldahl method [55 ].

Leaves and fruits were harvested from Tounsi pomegranate trees in October 2021 from Mahdia region, Tunisia. Variety authenticity was confirmed by taxonomist Dr. Faten Zaouay from the Department of Horticulture, Higher Agronomic Institute, Chott-Meriem (University of Sousse, Tunisia) and a voucher specimen was deposited in our national collection maintained in duplicate at Gabes and Chott-Mariem (Sousse), with the code ‘TNl, TN2, TN3, TN5, TN5”.
Pomegranate extracts were prepared as described by our previous study [11 (link)]. Fruits were washed and hand-peeled. Arils were squeezed using a commercial blender (moulinex, France). The extract juice was centrifuged at 15000 rpm for 15 min. Then the supernatant was recuperated and lyophilized. Leaves, flowers and fruit peel were dried, powdered and extracted with methanol (MeOH) 50 g/250 ml in the dark for 48 hours. Each extract was filtered through Whatman No. 42 filter paper and evaporated to dryness using a rotary evaporator (Heidolph, Germany) under vacuum at 45 °C and stored at − 20 °C for further determination. Pomegranate seeds were dried and powdered. Oil was extracted by the methods of soxhlet. About 30 g seeds were extracted with 200 ml of hexane at room temperature for 6 h. The solvent was removed by evaporation at 40 °C and the oil was flushed with nitrogen stream and stored at − 20 °C in sealed tubes.