Recent advances in the valorization of palm and date wastes for water and wastewater treatment: a review

Palm and date processing generate substantial quantities of lignocellulosic residues which remain underutilized despite their chemical suitability for conversion into water treatment materials. This review synthesizes research from 2017 to 2025 on the valorization of palm/date biomass into sorbents, catalytic media, and hybrid systems for the removal of heavy metals, phenolic compounds, and textile dyes from aqueous matrices. Across the surveyed literature, modified carbons achieved high pollutant removal efficiencies, including >95% for Pb2+, >90% for Cd2+, 85–100% for Cr(VI), and 80–99% for Zn2+, with reported adsorption capacities up to ∼30 mg·g−1 for Pb2+, ∼114 mg·g−1 for Cd2+, and ∼22 mg·g−1 for Cr(VI). For phenolic pollutants, triethylamine-modified fibers reached 191.75 mg·g−1 for 2,4,6-TCP, iron-oxide bio-carbon reached 72.46 mg·g−1 for phenol, and Ag-decorated cellulose beads enabled complete 4-nitrophenol conversion within 7 min. Dye sorbents reported q_max values of 110 mg·g−1 (SBL dye) and 425.16 mg·g−1 (Eriochrome Black-T). Adsorption behavior was predominantly described by Langmuir or Freundlich isotherms and pseudo-second-order kinetics. Several systems demonstrated functionality under real matrices (landfill leachate, refinery wastewater, groundwater) and, in some cases, met WHO water quality criteria. Remaining challenges relate to continuous operation, multi-ion competition, regeneration, and techno-economic feasibility.