Spirulina platensis‐capped mesoporous magnetic nanoparticles for the adsorptive removal of chromium

Abstract

The magnetic nanoparticles prepared through the co-precipitation method were surface modified using Spirulina platensis. The mesoporous and superparamagnetic nature of the adsorbent was confirmed by Brunauer-Emmett-Teller (BET) and vibrating sample magnetometer (VSM) analyses, respectively. Further, an increased specific surface area of 75.3 m 2 /g was reported in the BET studies. Parameters such as pH, contact time, concentration, and temperature were studied to optimize the operating conditions influencing adsorption. Thermodynamic studies justified the spontaneity and endothermic nature of adsorption. The adsorbent exhibited a better performance at 1.5 pH and 120 minutes of contact time. The monolayer adsorption capacity of the material was found to be 29.23 mg/g from the evaluation of Langmuir adsorption isotherm. The second-order kinetic studies suggest the predominance of chemisorption. Further, the X-ray photoelectron spectroscopy (XPS) studies confirmed that the adsorption mechanism is electrostatic attraction accompanied by reduction. Notably, a regeneration efficiency of 75.26% was achieved with NaOH as the desorbing agent.

Sustainable approach for adsorptive removal of cationic and anionic dyes by titanium oxide nanoparticles synthesized biogenically using algal extract of Spirulina

“…This, surely states that the adsorption obeys pseudo 2nd order in instance of both MO and MG and it takes place chemically. K 1 and K 2 determined to be −0.014 and 0.00344 respectively for MO and −0.001 and 0.00619 respectively for MG, in both the cases, a greater value of K 2 confirms that the process obey pseudo 2nd order [3,22,44]. Three crucial processes are involved in the process of dye adsorption on nanoparticles: (i) film diffusion; (ii) diffusion within the particle; and (iii) interaction between the ions of dyes and active sites of nanoparticles.…”

“…One of the key characteristics for guaranteeing a nanomaterial's reusability is its capacity for regeneration. Desorption studies offer important details on the reusability of nanomaterials and the adsorption mechanism [22][23][24]. As a result, two eluents, H 2 O and NaOH, were utilized to investigate the ability of STONPs to regenerate.…”

“…The value of S D  is 68.535 J K −1 mol −1 and 40.4502 J K mol −1 for MO and MG respectively, the positive value of S D  is a symbol for the fact that randomness rises while adsorption takes place. G D  was discovered to be in negative, for both MO and MG which designate the spontaneous reaction [22,48]. Figure 22 represents Thermodynamic model plots for both dyes.…”

“…Figure21depicts the results. Adsorption efficiency rises with temperature, indicating an endothermic (heat-absorbing) process[22, 44, 47].Van't Hoff plot was used to pursue more thermodynamic analysis. Equations (19)-(22) depict several thermodynamic study factors.…”