# Adsorption of Ibuprofen from Water Using Waste from Rose Geranium (_Pelargonium gravelens_) Stems
## 4 Conclusions  
In this study, the stem of rose geranium was used as an adsorbent for ibuprofen. The material was characterised by SEM-EDX, FTIR, TGA, and BET. The SEM images showed that the morphology of the SPG exhibited a rough surface texture with voids and pores. The FTIR spectrum showed the presence of groups such as \(-\)OH, \(-\)C=O, \(-\)COC, and \(-\)NH on the surface of the adsorbent. The chemical and physical properties of SPG played an important role in the removal of IBU. IBU was found to be present as a neutral molecule in the solution at pH 1 and 3, limiting the interaction and resulting in low uptake. At pH 5, IBU was slightly ionised and coexisted as a neutral and anionic species. Under alkaline conditions at pH 7, IBU was completely ionised and existed as an anion, which improved removal. The trend of IBU adsorption showed that the adsorption capacity increases when the initial concentration of working standards is increased. The data for the time effect showed that the adsorption rate was fast in the initial phase between 1 and 45 min. This was followed by a slow adsorption rate leading to little to no adsorption in time intervals  
Figure 10: Reusability study on SPG for ibuprofen.  
\begin{table}
\begin{tabular}{c c c} \hline
**Biosorbent** & **q\({}_{\text{e}}\) (mg/g)** & **Reference** \\ \hline Carbon/magnetic NP & 51.00 & [32] \\ Blend carbon & 45.58 & [5] \\ Pomegranate husk/Fe(II)-Fe(III) NP & 39.80 & \\ Stem of rose geranium & 34.88 & This study \\ Biochar from walnut shells & 30.10 & [33] \\ Hemp seeds-MnO/CuO & 26.50 & [4] \\ Sugarane waste & 13.51 & [34] \\ Carbon from olive seeds & 9.090 & [35] \\ Mugwort leaves & 6.800 & [36] \\ \hline \end{tabular}
\end{table}
Table 5: Comparison study of the removal of IBU using similar materials.  
between 65 and 105 min. The data corresponded to the Langmuir and PFO models. The \(\Delta\)H\({}^{0}\) value shows that the adsorption of IBU on SPG was controlled by physisorption due to weak van der Waals forces. The obtained values of \(\Delta\)G\({}^{0}\) are negative, indicating that the uptake of IBU was spontaneous. The reusability of SPG showed good uptake for three cycles with an efficiency of more than 65%; thereafter, the adsorbent showed limited efficiency. Overall, the results for low-cost SPG show great potential and feasibility for water treatment. Future research for SPG includes carbonization at different temperatures using various techniques such as furnace, microwave, and hydrothermal energy, followed by carbon activation with acids and bases. Such materials should also be investigated for the adsorption of other emerging pollutants.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15137203/s1](https://www.mdpi.com/article/10.3390/app15137203/s1)]([https://www.mdpi.com/article/10.3390/app15137203/s1](https://www.mdpi.com/article/10.3390/app15137203/s1)).  
Conceptualization, N.D.S. and P.M.T.; methodology, P.M.T.; validation, N.D.S. and P.M.T.; formal analysis, P.M.T.; investigation, P.M.T.; resources, P.M.T.; data curation, P.M.T.; writing--original draft preparation, N.D.S. and P.M.T.; writing--review and editing, N.D.S.; visualization, N.D.S. All authors have read and agreed to the published version of the manuscript.  
Vaal University of Technology, Vanderbijpark, South Africa, funded this work.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors declare no conflicts of interest.