# Adsorption of Ibuprofen from Water Using Waste from Rose Geranium (_Pelargonium gravelens_) Stems
## 1 Introduction  
The widespread and extensive use of pharmaceutical products, while being beneficial, has also led to environmental problems worldwide and has been detected in soil, municipal sewage systems, and surface water [1]. Pharmaceuticals include a wide range of compounds such as anti-inflammatory drugs, antiretrovirals (ARVs), vaccines, steroids, painkillers, etc. [2].  
Ibuprofen (IBU), 2-[4-(2-methylpropyl) phynyl] propanoic acid (C\({}_{13}\)H\({}_{18}\)O\({}_{2}\)), is a well-known commonly used drug, with an annual consumption of more than 2 million tons. It is non-steroidal and anti-inflammatory and is usually prescribed to relieve inflammation, osteoarthritis, and rheumatoid arthritis. It is also an analgesic and mixed with other medicines to relieve fever and pain [3, 4]. IBU cannot be fully metabolised in the human digestive system, and its derivatives are released from the human body through natural processes such as urination and defecation and eventually leached into the water. Prolonged intake of water containing IBU or its derivatives leads to bioaccumulation and has toxic effects on the environment, human health, and aquatic organisms [5]. Several studies have reported that the concentration of IBU is increasing in rivers and wastewater treatment plants in many countries, posing serious health and environmental risks. IBU originates from the wastewater of pharmaceutical product manufacturers, hospital effluents, theimproper disposal of expired medications, the exceta of patients taking medication, and animal husbandry [6].  
The adverse effects of IBU necessitate its removal from the environment and water. Several treatment methods, including precipitation, coagulation, ion exchange, filtration, advanced oxidation [7], etc., were developed to remove pollutants from aqueous solutions. Adsorption is one of the favoured methods because it is inexpensive and effective, does not use harmful chemicals, and produces no sludge [8]. The versatility of adsorption is demonstrated by the possibility of using different materials, such as activated carbon [9], agricultural waste, zeolites [10], etc., as adsorbents.  
Agricultural waste materials are economical and abundant in nature. These include pompegranate peels, papaya seeds, coconut shells and spend green tea [11], fennel seeds, hemp seeds, twigs and roots, avocado seeds, paper waste, black cumin seeds, etc. These natural materials have active sites such as oxygen-rich functional groups on their surface that can effectively bind pollutants and a porous surface that can trap pollutant molecules in water [12; 13; 14; 15; 16; 17].  
Rose geranium is a bushy, evergreen plant that is native to South Africa and is also found in many countries worldwide. Its unique essential oil, contained in the leaves, flowers, and stems of the plant, contains compounds such as geranial, linalool, etc [11]. The oil is highly commercialised and used in the food industry for flavouring and preservation, the pharmaceutical industry for its antibacterial and antifungal properties, and the perfume industry. After the oil is extracted from the plants, tons of waste are produced, which usually end up in the environment without any alternative use. To the best of our ability, we located a single document that reports on the use of carbon from rose geranium leaves activated by phosphoric acid (H\({}_{3}\)PO\({}_{4}\)) for the removal of ibuprofen from water. The great potential of using geranium leaves as an adsorbent in water purification provides a good basis for using other parts of geranium.  
This research creates an alternative use for waste rose geranium stems by using them as adsorbent to remove IBU from water. In this study, we characterised the adsorbent and carried out the adsorption of ibuprofen by varying influential parameters such as initial concentration, pH of the solution, temperature of the system, and contact time.