# Valorization of Date Fruit (_Phoenix dactylifera_ L.) Processing Waste and By-Products: A Review
## 4. Valorization Approaches of Date Processing Waste
### Water Desalination and Purification  
Water scarcity is a growing concern worldwide, and many regions are turning to desalination as a means of addressing the issue. Desalination refers to the technique of separating salts and other minerals from seawater or brackish water to make it potable and suitable for consumption and irrigation purposes [113]. However, desalination is an energy-intensive process and can have environmental impacts, such as the discharge of brine into the ocean [113]. One potential solution to these challenges is the use of date processing waste in desalination processes. Date processing waste, such as date pits and leaves, contain high amounts of tannins and other organic compounds that can be used in the desalination process. The potential uses of date processing waste include its application in seawater pretreatment as a preliminary step before desalination [114]. Pretreatment is a critical step in desalination that involves removing suspended solids, colloids, and other impurities from the feed water [114]. Date processing waste can be used as a natural coagulant and flocculant to enhance the removal of impurities during pretreatment [114]. [PERSON] et al. [115] investigated the utilization of date palm empty fruit bunches (DPEFBs) as a sustainable biosorbent for hexavalent chromium (Cr\({}^{6+}\)) removal from synthetic wastewater. The pretreated DPEFB was analyzed for its morphology and surface chemistry using scanning electron microscopy, energy dispersive elemental analysis, and Fourier-transform infrared spectroscopy. Various biosorption parameters, including pH, biosorbent dosage, contact time, temperature, initial feed concentration, and agitation speed, were examined for their impact on Cr\({}^{6+}\) removal by DPEFB, and they found that the DPEFB sorbent exhibited an isoelectric point at pH 2, becoming dehydrated above this value to capture positively charged Cr\({}^{6+}\) ions. Optimal conditions for chromium removal were identified as pH 2, 0.3 g dosage, 100 rpm agitation speed, 120 min contact time, 50 mg/L initial feed concentration, and 30 \({}^{\circ}\)C operational temperature. Furthermore, DPEFB demonstrated reusability with NaNO\({}_{3}\) as an effective regenerant, allowing for up to three successive biosorption-desorption cycles without significant loss in efficiency. This study establishes DPEFB as an efficient, cost-effective, and eco-friendly biosorbent for removing toxic Cr\({}^{6+}\) ions from wastewater, offering a sustainable approach to address this environmental concern. Date-palm-coir-waste-derived nano-activated carbon (DPC-AC) as a cost-effective solution for removing 2,4-DPA herbicide from the water was also investigated by [PERSON] et al. [116]. DPC-AC, created through a one-step process, exhibited strong adsorption properties with a 98.6% removal rate under optimal conditions. It followed Langmuir isotherm and pseudo-second-order kinetics, and thermodynamic analysis confirmed its efficiency. The study also highlighted the nanosorbent's electrostatic and chemical interactions with 2,4-DPA, showcasing its potential for water treatment. Additionally, cost analysis and regeneration tests emphasized its economic feasibility and reusability, turning date palm coir waste into a valuable resource for pollution control. In a recent study conducted by [PERSON] et al. [83], they successfully demonstrated the effective treatment of aqueous effluents containing the 2,4-DPA herbicide using modified date palm leaf waste with sulfuric acid. The resulting product exhibited an amorphous structure characterized by numerous cavities, pore connectivity, and oxygen-bearing functionalities, facilitating the efficient removal of 2,4-DPA from water sources. The adsorption process was favorable, spontaneous, and exothermic from a thermodynamic standpoint. Additionally, reusability tests confirmed that the product could be regenerated using a NaOH regenerant and employed for up to five cycles to remediate 2,4-DPA-contaminated wastewater.