Investigation of Moringa oleifera seeds as effective and low-cost adsorbent to remove yellow dye tartrazine in fixed-bed column

Potential of Capparis decidua plant and eggshell composite adsorbent for effective removal of anionic dyes from aqueous medium

The presence of hazardous dyes in wastewater poses significant threats to both ecosystems and the natural environment. Conventional methods for treating dye-contaminated water have several limitations, including high costs and complex operational processes. This study investigated a sustainable bio-sorbent composite derived from the Capparis decidua plant and eggshells, and evaluated its effectiveness in removing anionic dyes namely tartrazine (E-102), methyl orange (MO), and their mixed system. The research examines the influence of initial concentration, contact time, pH, adsorbent dosage, and temperature on the adsorption properties of anionic dyes. Optimal removal of tartrazine (E-102), methyl orange (MO), and their mixed system was achieved at a pH of 3. The equilibrium was achieved at 80 min for MO and mixed systems, and 100 min for E-102. The adsorption process showed an exothermic nature, indicating reduced capacity with increasing temperature, consistent with heat release during adsorption. Positive entropy values indicated increased disorder at the solid-liquid interface, attributed to molecular rearrangements and interactions between dye molecules and the adsorbent. Isotherm analysis using Langmuir, Freundlich, Temkin, and Redlich-Peterson models revealed that the Langmuir model best fit the experimental data. The maximum adsorption capacities of 50.97 mg/g, 52.24 mg/g, and 56.23 mg/g were achieved for E-102, MO, and the mixed system under optimized conditions, respectively. The pseudo-second-order kinetic model demonstrated the best fit, indicating that adsorption occurs through physical and chemical interactions such as electrostatic attraction, pore filling, and hydrogen bonding. Hence, the developed bio-sorbent could be a sustainable and cost-effective solution for the treatment of anionic dyes from industrial effluents.

Continuous successive cycles of biosorption and desorption of acid red 27 dye using water hyacinth leaves as an effective, economic, and ecofriendly biosorbent

We investigated the capacity of water hyacinth leaves (LEC) to biosorb 75 mg/L acid red 27 (AR27) in a continuous system comprising 30 successive biosorption/desorption cycles in a packed-bed column at pH 2.0 and 56.5 L/m²·h volumetric flux. Using 0.025 M NaHCO₃ eluent at 113 L/m²·h volumetric flux, all the dye was desorbed (100% desorption efficiency) from the loaded LEC biomass within 5-6 h. The same biosorbent was used for 147.5 consecutive days. The AR27 biosorption capacity, breakthrough time, and exhaustion time decreased from 69.4 to 34.5 mg/g, 74.81 to 14.1 h, and 101.1 to 34.1 h, respectively, and the critical bed height increased from 1.04 to 2.35 cm, as the number of biosorption/desorption cycles increased from 1 to 30. LEC life factor based on biosorption capacity predicted that the packed bed would be exhausted after 51.95 cycles. LEC is a promising biosorbent for bioremediation of AR27-laden wastewaters.

Ultrasonic supported dye removal by a novel biomass

Sumac Leaves (Rhus Coriaria L), were used as a possible adsorbent of Basic Blue 3 (BB3) removal. The main affecting parameters on adsorption such as concentration, pH and temperature were investigated. Adsorption equilibrium was reached in 30 min. The ultrasonic effect was also enhanced the dyestuff removal. Adsorption capacity was rised from 0.566 to 1.826 mg/g, as rising the concentration from 4 μg/mL to 10 μg/mL. Several isotherm models including Langmuir, Freundlich and Temkin were applied for explaining the adsorption mechanism. Temkin and Langmuir isotherm models describe the system well. Pseudo first order, pseudo second order and intra particle kinetics were evaluated. Pseudo second order diffusion model supports the adsoprption and also intra particle diffusion plays an important role for BB3 removal. Thermodynamics of the adsorption were commented. −2219.5 J/mol of Gibbs energy showed us a spontaneous and physical adsorption.

Continuous biosorption of acid red 27 azo dye by Eichhornia crassipes leaves in a packed-bed column

In this work, the biosorption behavior of acid red 27 (AR27) dye using Eichhornia crassipes leaves (LECs) in a packed-bed column was investigated by varying relevant operational parameters and assessment of mathematical models. Results showed that the zero-charge point of LECs was 2.37 and that optima pH and volumetric flux of the influent solution for AR27 biosorption were 2.0 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$56.5\ \hbox {L}/\hbox {m}^{2}\cdot \hbox {h}$$\end{document}56.5L/m2·h, respectively. The maximum specific and volumetric biosorption capacities were observed at influent AR27 concentrations and with LEC bed heights ranging between 50 and 400 mg/L and 2 and 8 cm, respectively. It was also found that if LEC bed height was increased and volumetric flux and AR27 concentration of the influent solution decreased, service and saturation time increased. Modeling results revealed that the Thomas, bed depth service time, Yoon–Nelson, dose-response, and logistic models accurately described the dynamic performance of the packed-bed column in terms of pH, AR27 concentration, and volumetric flux of influent AR27 solution, as well as that of LEC bed height. The findings revealed that LECs exhibited remarkable potential for the biosorption of AR27 from aqueous solutions in a packed-bed column and could potentially be useful for the treatment of AR27-laden wastewater.