*2.2. Synthesis of Copper Nanoparticles*

The production of green copper nanoparticles was performed using green tea leaf extracts, according to the technique explained by Asghar [25]. Green tea leaves were purchased from a local market in Cairo (Egypt). The leaf extracts of each tea were separated by exactly weighing 10 g of tea leaves and transferring into a 250 mL conical flask already containing 100 mL of DI-H2O. The mixtures were then heated at 80 ◦C for 10 min, cooled and filtered. Copper nanoparticles from black tea were synthesized using a CuSO4 solution with the corresponding tea leaves extract. Briefly, CuSO4 (1 mmol/L) and tea leaf extracts were used in a 4:1 ratio by volume, and the solution was subjected to continuous stirring at 80 ◦C for 10 min. The resultant suspensions were settled at room temperature for 24 h to complete the reaction, then filtered and washed three times with DI-H2O to remove any unbound molecules. Lastly, Cu-NPs were dried at 65 ◦C for 3 h.

### *2.3. Synthesis of Fe*− *Nanoparticles*

Black tea leaves were used to prepare Fe− nanoparticles. Black tea leaves was washed many times with tap water and then with double distilled water to eliminate impurities. The washed tea was dried at 105 ◦C for 24 h in a hot air oven and then powder form obtained after grinding of dried tea. Extraction procedure was carried out according to Anamika et al. [14]. An extraction of tea sample was prepared with a 1:10 ratio of tea powder to water, and the extraction was carried out at 80 ◦C for 30 min. Then the extract was filtered after cooling at room temperature and then 0.1 M of FeSO4 solution was added to the tea extract at a ratio of 1:3 (1-part FeSO4 and 3-part extract) [26,27]. Then sodium hydroxide solution was added, dropwise. During this process, the ferrous ions were converted into nanometallic particles rapidly. Separation of prepared black nanoparticles was performed by filtration and then washed with double distilled water. Separated nanoparticles were subsequently dried in a vacuum at 50 ◦C for 24 h.

#### *2.4. Preparation of ZV Fe–Cu/Alg–LS Nanocomposites*

In order to formulate ZV Fe–Cu/Alg–LS nanocomposites, 2% (*w*/*v*) adsorbents of sodium alginate and 7 g of limestone were mixed in 100 mL of distilled water. The combination was stirred with a mechanical stirrer and heated on a hot plate to 80 ◦C. When the mixture of limestone and alginate attained a homogeneous condition, a solution of

mixed zero valance Fe–Cu (0.5 Fe–0.5 Cu in 100 mL) was added. Then 0.3 M of calcium chloride was dripped through a syringe injector into to form beads. In order to obtain hardened beads, the beads were submerged in a calcium chloride (CaCl2) solution for 12 h. Washing the adsorbents with distilled water several times removed the excess unbounded calcium chloride from the adsorbent surface.
