## 2 Methods of Eliminating Hormones and Pharmaceuticals
### Physical Methods  
#### 2.1.1 Adsorption  
The adsorption process can be cumbersome to manage because of the generation of sludge. In addition, it can hinder separation and cause the release of adsorbed organic micropollutants in the nanofiltration (NF) process. The disadvantages of this process are the formation of by-products and the rapid saturation of activated carbon with contaminants. Adsorption as a process for the elimination of hormones and pharmaceuticals depends on the pH of the solution, the type of absorbent, and the composition of the water in terms of the amount and type of compound, as well as other substances contained in the water. The adsorption efficiency of hormones and pharmaceuticals from wastewater is strongly dependent on the pH of the solution, with numerous studies showing that lower pH values favour more efficient removal of these micropollutants [50; 51; 52; 53]. This is mainly due to the effect of pH on the adsorbent surface charge and the chemical form of the adsorbed compounds. Under acidic conditions, the surface of an adsorbent such as activated carbon often has a positive charge, which favours the adsorption of anionic or undissociated pharmaceutical and hormone molecules, which are more hydrophobic under these conditions and bind more readily to the adsorbent surface [51; 53]. In addition, competition from other ions present in the solution, such as OH- or HCO\({}_{3}\)-, which can occupy active adsorption sites in alkaline environments, is reduced at low pH [54]. Granular activated carbon (GAC) has been shown to eliminate 98% of E2, 95.4% of progesterone (PRG), and 97.05% of EE2 from wastewater [55; 56; 57]. On the contrary, magnetic graphene oxide removed 95.20% of EI, 79.40% of E2, 93.20% of EE2, 88.40% of E3, and 98.20% of17\(\alpha\)-E2. Hybridised graphene oxide sheets removed EE2 and E2 with efficiencies of 98% and 97%, respectively [16]. In addition, multi-walled carbon nanotubes and single-walled carbon nanotubes removed EE2 with efficiencies of 97% and 98%, respectively [58]. Double sodium hydroxide coated with sodium dodecyl sulphate removed up to 94% of E2, and tea leaf waste eliminated PRG at levels exceeding 68% [59]. Alternative materials such as spent coffee grounds, almond shells, biocarbons, potato-dextrose agar, and chitin have been tested to remove some oestrogens and progesterone and have shown high removal efficiencies (Table 2) [17; 55; 60; 61]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Absorbent**} & \multicolumn{2}{c}{**Effectiveness of Removal**} & \multirow{2}{*}{**Contact Time**} & \multirow{2}{*}{**Amount of Adsorbent**} & \multirow{2}{*}{**Amount of Adsorbate**} \\ \cline{2-2} \cline{4-4}  & **E2** & & & \\ \hline Coffee grounds & 100\% & 15 min & 0.1 g & 10 mg/L \\ \hline Almond shells & 100\% & 40 min & 0.5 g & 100 mg/L \\ \hline Biocarbon & 100\% & 60 min & 0.5 g & 50 mg/L \\ \hline Potato-dextrose agar & 100\% & & & \\ \hline Double sodium hydroxide with layer & 94\% & 20 vmin & 2 g/L & 0.302–0.379 mg/L \\ of sodium dodecyl sulphate & & & & \\ \hline Chitin & \textgreater{}82\% & 220 min & 1.45 g/L & 5.7 mg/L \\ \hline Sp2 hybridised graphene oxide sheets & 97.19\% & 98.46\% & 30 min & \\ \hline Black tea leaf waste & 95.75\% & 60 min & 0.5 g & 100 mg/L \\ \hline Granular activated carbon & 97.05\% & 95.40\% & 120 min & 10 mg/L & 200 ng/L \\ \hline Multi-walled carbon nanotubes & & 97\% & 24 h & 0.5 mg/L & 2.5 mg/L \\ \hline Single-walled carbon nanotubes & & 98\% & \textgreater{}5 h & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Degree of reduction in hormones with selected adsorbents; authors’ own elaboration based on [17; 55; 60; 61]. The use of metal-organic frameworks (MOFs) for the adsorptive removal of hormones and pharmaceuticals from wastewater has progressed significantly in recent years.