Kinetics and Thermodynamic Studies for Removal of Trypan Blue and Methylene Blue from Water Using Nano Clay Filled Composite of HTAB and PEG and its Antibacterial Activity

This work describes the preparation of new eco-friendly adsorbents with a simple method. At first, Montmorillonite (MMT) was modified with surfactant HTAB (MMT@HTAB) and then with polymer PEG (MMT@HTAB@PEG). The as-synthesized materials were characterized by several characterization techniques, including XRD, FTIR, SEM, TEM, TGA, N2 adsorption/desorption isotherm analysis by the BET method and zeta potential measurement then evaluated as adsorbents for removal of both methylene blue (MB) as a cationic dye and trypan blue (TB) as the anionic dye from aqueous solution under different contact time, dye concentration, temperature, and pH. The obtained results confirm the intercalation of surfactant within the clay layers, while the obtained nanocomposite showed different morphologies and structures in which the exfoliated and intercalated forms were obtained. The maximum adsorption capacity of TB and MB was found to be 190.81 and 237.22 mg/g, respectively, with MMT@HTAB@PEG adsorbent in an initial concentration of 100 mg/L at alkaline pH in 35 min and a temperature of 25 °C. The adsorption kinetics of TB and MB on MMT@HTAB@PEG was best fitted by the pseudo-second order model, and the isotherms results reveals better consistency of the Langmuir model, indicating that the adsorption is favorable and in the form of multilayers. The thermodynamic study showed that the adsorption processes of TB and MB by the both MMT@HTAB and MMT@HTAB@PEG adsorbents occur in an autonomous way and the temperature has not a significant effect on the adsorption capacity of TB and MB dyes. In addition, MMT@HTAB showed good antibacterial activity against both Escherichia coli (ATCC 8739) and Micrococcus luteus (ATCC 9341) bacteria compared to MMT@HTAB@PEG. The broadcast area was found to be 6 and 5 mm in Escherichia coli (ATCC 8739) and Micrococcus luteus (ATCC 9341), respectively

Adsorption behavior of MB dye on alginate-sepiolite biocomposite beads: Adsorption, kinetics, and modeling

This work is based on the preparation of biocomposite beads Alginate-Sepiolite using a simple preparation method. A series of materials was prepared by varying only the mass of the sepiolite in the biocomposite beads (mass of the sepiolite is varied between 0.5–1.5 g in the reaction mixture). The obtained biocomposites were characterized by XRD, FTIR, TGA, XRF, SEM, and EDX and then tested as adsorbents for the removal of Methylene Blue MB dye in an aqueous solution. To study the adsorption behavior of MB dye on biocomposites, several parameters affecting MB adsorption were investigated and discussed. The results obtained showed that the ALG-Sep composite hydrogels were well formed, and their properties were improved depending on the sepiolite content used. The kinetics and modeling results show that the adsorption process follows first-order kinetics, and the Langmuir model. It was found that the adsorption capacity of MB dye increased with the increase of sepiolite in the composite beads, and adsorption was carried out in the following order ALG-Sep(1.5) \u3e ALG-Sep(1) \u3e ALG-Sep(0.5). The maximum absorption capacity of MB dye on ALG-Sep(1.5) was qmax = 55.49 mg.g−1. Among the advantages of this biocomposite is that it is prepared from natural and non-toxic sources, and it is easily separable after adsorption, which makes it an excellent candidate for the elimination of organic pollutants in polluted waters

Removal of crystal violet dye using a three-dimensional network of date pits powder/sodium alginate hydrogel beads: Experimental optimization and DFT calculation

Biodegradable and very low-cost adsorbent beads were prepared from date pits powder (DP) and sodium alginate (SA). DP to SA ratios was varied (1/2; 1/4 and 1/6) and used to eliminate Crystal violet (CV) a cationic dye. Adsorbents were characterized by FTIR, SEM-EDS, UV–vis DR, TGA and the point of zero charge (pHPZC). The optimal composite beads SA@6DP show high adsorption capacities of 83.565 mg/g toward CV than SA@2DP and SA@4DP. The kinetics investigation showed that the adsorption is well described by the pseudo-second-order kinetic (R2 = 0.998). The thermodynamics and isotherms studies exhibit that the adsorption phenomenon for SA@6DP adsorbent is endothermic and significantly fitted with the Redlich-Peterson model. The experimental adsorption tests were optimized by the Box-Behnken design (BBD) which led to conclude the maximal CV removal obtained by SA@6DP was 99.873 % using [CV] = 50 mg/L, adsorbent mass = 20 mg and 48 h of contact time. The theoretical calculation proved that the CV molecules favor the mode of attack due to their electrophilic character and can accept the SA@6DP adsorbent electrons more easily to form an anti-bonding orbital. SA@6DP hydrogel beads are therefore an exceptional bio-adsorbent that offers excellent adsorption performance