In this study, Rosa damascena leaf powder was evaluated as a biosorbent for the removal of copper from aqueous solutions. Process variables such as the biosorbent dose, pH, and initial copper concentration were optimized using response surface methodology. A quadratic model was established to relate the factors to the response based on the Box–Behnken design. Analysis of variance (ANOVA) was used to assess the experimental data, and multiple regression analysis was used to fit it to a second-order polynomial equation. A biosorbent dose of 4.0 g/L, pH of 5.5, and initial copper concentration of 55 mg/L were determined to be the best conditions for copper removal. The removal of Cu²⁺ ions was 88.7% under these optimal conditions, indicating that the experimental data and model predictions were in good agreement. The biosorption data were well fitted to the pseudo-second-order and Elovich kinetic models. The combination of film and intra-particle diffusion was found to influence Cu²⁺ biosorption. The Langmuir and Dubinin–Radushkevich isotherm models best fit the experimental data, showing a monolayer isotherm with a q_max value of 25.13 mg/g obtained under optimal conditions. The thermodynamic parameters showed the spontaneity, feasibility and endothermic nature of adsorption. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the biosorbent before and after Cu²⁺ biosorption, revealing its outstanding structural characteristics and high surface functional group availability. In addition, immobilized R. damascena leaves adsorbed 90.7% of the copper from aqueous solution, which is more than the amount adsorbed by the free biosorbent (85.3%). The main mechanism of interaction between R. damascena biomass and Cu²⁺ ions is controlled by both ion exchange and hydrogen bond formation. It can be concluded that R. damascena can be employed as a low-cost biosorbent to remove heavy metals from aqueous solutions.

Methyl violet 2B dye is a major contaminant that is detrimental to both humans and aquatic microorganisms, thus it should be eliminated from water. In the current investigation, the biosorption of methyl violet 2B dye onto the brown seaweed Cystoseira tamariscifolia biomass as a sustainable low-cost biosorbent was examined by varying biosorption parameters. Biomass dosage of 7 g/L, pH 6, a temperature of 45 °C, a 60 min contact time, and a 30 mg/L initial dye concentration were determined to be the optimum biosorption conditions. Data obtained were interpreted by thermodynamic, isothermal, and kinetic models. The thermodynamic studies demonstrated that the process of dye biosorption was random and endothermic. The data were best described by Langmuir, Dubinin–Radushkevich, and Temkin models. According to the Langmuir equation, the maximal biosorption capacity (q_max) was 10.0 mg/g. Moreover, the pseudo-second-order mechanism is dominant, and chemical biosorption might represent the rate-controlling stage in the biosorption process. However, intraparticle diffusion revealed a boundary layer effect. A scanning electron microscope, energy-dispersive X-ray spectroscopy, the point of zero charge, and Fourier Transform Infra-Red were applied to characterize the algal biomass, exhibiting its remarkable structural properties and the availability of several functional groups. Additionally, ion exchange, electrostatic force, and hydrogen bonding formation are all proposed as biosorption mechanisms. As a result, C. tamariscifolia was evaluated to be a sustainable biosorbent for dye biosorption from aqueous solutions.

The aim of this study was to assess the efficiency of Spirulina platensis for removing Zn²⁺ ions from the aqueous solutions. The optimized conditions of 4.48 g/L algal dose, pH of 6.62 and initial zinc concentration of 29.72 mg/L obtained by response surface methodology were employed for Zn²⁺ biosorption by S. platensis and up to 97.90% Zn²⁺ was removed, showing that there is a favorable harmony between the experimental data and model predictions. Different kinetic and equilibrium models were used to characterize the biosorption manner of Spirulina as a biosorbent. The kinetic manner of Zn²⁺ biosorption was well characterized by the pseudo-second-order, implying that the adsorption process is chemical in nature. The Langmuir and Dubinin–Radushkevich isotherm models were best fit to the equilibrium data. The maximum adsorption capacity of the Langmuir monolayer was 50.7 mg/g. Furthermore, the thermodynamic analysis revealed that Zn²⁺ biosorption was endothermic, spontaneous and feasible. As a result of biosorption process, FTIR, SEM, and EDX investigations indicated noticeable alterations in the algal biomass’s properties. Therefore, the dried Spirulina biomass has been shown to be cost-effective and efficient for removing the heavy metals, particularly zinc ions from wastewater, and the method is practicable, and environmentally acceptable.

This study investigated the phytochemical contents of Taif’s rose pruning wastes and their potential application as phytomedicine, thereby practicing a waste-recycling perspective. In the Al-Shafa highland, four Taif rose farms of various ages were chosen for gathering the pruning wastes (leaves and stems) for phytochemical and pharmacological studies. The leaves and stems included significant amounts of carbohydrates, cardiac glycosides, alkaloids, flavonoids, and other phenolic compounds. The cardiac glycoside and flavonoid contents were higher in Taif rose stems, while the phenolic and alkaloid contents were higher in the plant leaves. Cardiovascular glycosides (2.98–5.69 mg g⁻¹), phenolics (3.14–12.41 mg GAE g⁻¹), flavonoids (5.09–9.33 mg RUE g ⁻¹), and alkaloids (3.22–10.96 mg AE g⁻¹) were among the phytoconstituents found in rose tissues. According to the HPLC analysis of the phenolic compounds, Taif’s rose contains flavonoid components such as luteolin, apigenin, quercetin, rutin, kaempferol, and chrysoeriol; phenolics such as ellagic acid, catechol, resorcinol, gallic acid, and phloroglucinol; alkaloids such as berbamine, jatrorrhizine, palmatine, reticuline, isocorydine, and boldine. Warm water extract was highly effective against Bacillus subtilis, Escherichia coli, and Proteus vulgaris, whereas methanol and cold water extracts were moderately effective against Aspergillus fumigatus and Candida albicans. The study’s findings suggested that Taif’s rose wastes could be used for varied medical purposes.

The pollution of aquatic bodies by synthetic dyes is regarded as one of the most significant environmental issues, which has prompted greater research into effective and sustainable removal techniques. Even though there have been major efforts in the previous few decades, more study is still necessary to fully examine the long-term performance and usable applicability of adsorbents and different adsorption techniques for the removal of dye. In the present study, a brown marine macroalga Sargassum muticum was used as an effective and sustainable biosorbent for the crystal violet (CV) dye removal from aqueous solutions. The biosorbent was characterized by analysis of SEM, EDX, and FTIR. In order to evaluate the optimum conditions of CV biosorption, several parameters have been examined as a function of contact time, algal dose, initial concentration of CV, and pH. The maximum CV removal was obtained at 60 min contact time, 10 g/L algal dosage, 30 mg/L initial concentration of CV, and pH 6. The isothermal models of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin are best explained the equilibrium data obtained. At the optimum conditions, the maximum biosorption capacity of the algal biomass achieved from the Langmuir model was 39.1 mg/g. The kinetic adsorption models were also better explained using the pseudo-second-order and Elovich model, and the effect of the boundary layer was indicated using the intraparticle diffusion model as well as the chemisorption-controlled biosorption process. Thermodynamically, the process of CV biosorption was shown to be random, spontaneous, and endothermic. Furthermore, the proposed mechanism of CV dye biosorption onto algal biomass is regulated by hydrogen bond formation, electrostatic interaction, and ion exchange. These findings revealed that the biomass of S. muticum is a sustainable and promising material for the biosorption of water pollutants.