This review addresses the potential of low-cost adsorbents (LCAds) derived from agro-industrial and marine residues as sustainable alternatives for water purification. Although raw biomass offers economic advantages, its application is often limited by low surface area and reactivity. Consequently, this paper examined physicochemical modifications—such as pyrolysis, acid/alkali activation, and surface grafting—that enhance adsorptive properties. The superior performance of these modified materials in removing heavy metals, dyes, pesticides, and pharmaceuticals is highlighted. Furthermore, the transition from laboratory scale to industrial application faces key hurdles, such as biomass variability, reactor engineering, and regulatory gaps. Finally, future perspectives are presented, focusing on the integration of LCAds into hybrid treatment systems and their pivotal role in the circular economy for decentralized water management.

The combined approach of specific surface area (SSA), porosity, microprobe analysis (EMPA), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with EDX and infrared spectroscopy (FTIR) provided the mica mineral physico-chemical and morphological characterisation. The electrostatic surface properties were assessed through the determination of the Point of Zero Charge (pH_PZC) by the drift method and the electrokinetic mica mineral features represented by the Isoelectric Point (pH_IEP) which was carried out through zeta potential measurements. Adsorption tests were performed to correlate the surface charge behaviour of the mica mineral and its influence on the adsorption efficiency of two different dyes, namely: Safranin Orange (SO), as a cationic dye and Reactive Black 5 (RB5), as an anionic dye.The higher adsorption capacity SO dye was observed at pH 9 and achieved almost 83% of removal, while RB5 dye adsorption on mica surface had the highest result, about 45% of removal efficiency, on pH of 3. In both cases, the main mechanism identified that drove this results is the electrostatic force of attraction between the adsorbent edge surface charge (pH-dependent) and the ionic nature (anionic or cationic) of the pollutant dyes particles. The preliminary adsorption experiments demonstrated that the raw grounded mica mineral has a greater potential associated with its application on cationic dye removal in wastewater. The present study aimed to detail the main characteristics of the mica mineral in order to evaluate the potential use of such mineral residues in the removal efficiency of contaminated wastewater. GRAPHICAL ABSTRACT

The present study investigated the use of a biosorbent produced from Leucaena leucocephala pods for the removal of metformin from aqueous solutions. The pods were subjected to chemical and thermal treatments and were referred to as L. leucocephala modified, which was characterized using scanning electron microscopy (SEM). The parameters investigated in the sorption process were temperature, contact time, adsorbent dosage, pH, and initial metformin concentration. The experimental data were in accordance with the Langmuir isothermal model. The maximum adsorption capacity reached was 56.18 mg g⁻¹ at 313 K. In the kinetic study, stability was achieved in 300 min, with 53.24% removal, and the pseudo-first-order model agreed well with the experimental data. The thermodynamic parameters indicated a spontaneous, favorable, and exothermic reaction. The presence of NaCl, CaCl₂, and MgCl₂ negatively affected metformin adsorption. Thus, the importance of the study was that a developed material showed promising results in the removal of metformin, particularly because it is an innovative material, and there are no studies in the literature on drug removal using L. leucocephala.