Dye removal using novel adsorbents synthesized from plastic waste and eggshell: mechanism, isotherms, kinetics, thermodynamics, regeneration, and water matrices

Abstract

High-density polyethylene (HDPE) waste and chicken eggshell were used to synthesize three novel adsorbents, namely mesoporous graphene (MG), nano-eggshell modified graphene (nEMG), and nano-magnetic eggshell modified graphene (nM-EMG) for methyl red (MR) adsorption from simulated wastewater. The effects of adsorption conditions (pH, contact time, initial dye concentration, adsorbent dose, and temperature) were investigated. MG, nEMG, and nM-EMG were characterized using SEM, TEM, BET, EDX, XRD, and FTIR analyses. MG, nEMG, and nM-EMG had specific surface areas of 15, 31, and 179 m2/g and mean pore diameters of 27, 29, and 5 nm respectively. The equilibrium adsorption capacities of MG, nEMG, and nM-EMG were 5.6, 8.1, and 6.5 mg/g respectively at MR concentration of 100 mg/L, pH 4, adsorbent dose of 1.0 g/100 mL, and temperature of 25 °C. All MR sorption processes followed the pseudo-second-order and Langmuir–Freundlich model. The adsorption rates were controlled by intra-particle and film diffusion. MR uptake on the synthesized adsorbents was spontaneous, endothermic, and chemisorption. The adsorption occurred via electrostatic interactions, π electron interactions, and hydrogen bonding. The performance of the prepared adsorbents was examined in different water matrices and compared with other MR adsorbents. After five regeneration cycles, the adsorbent reusability study showed that nM-EMG is the most stable and reusable adsorbent.

A novel Corchorus olitorius-derived biochar/Bi 12 O 17 Cl 2 photocatalyst for decontamination of antibiotic wastewater containing tetracycline under natural visible light

“…Howbeit, the removal efficiency remained approximately the same with increasing the biochar dose from 150 mg/L to 200 mg/L. The biochar particles might agglomerate with increasing the biochar loading above 150 mg/L which could result in the decline of active area, thereby suppressing the expected higher removal at excessive biochar doses as reported by and Salama et al ( 2022) 37,38 . The same trend was observed for the generated intermediates, where the concentration of the generated by-products increased from 0.9 mg/L to 3.9 mg/L in the case of caprylic acid and from 0.…”

Removal of methyl red from wastewater using a NiO@Hyphaene thebaicaseed-derived porous carbon adsorbent: kinetics and isotherm studies

“…It has been reported that the increasing concentration of the dye boosts the mass transfer driving force via several collisions between dye molecules and the surface of the adsorbent at the initial stages of the adsorption process. 44 On the other hand, by increasing the MR concentration from 10 to 200 mg L À1 , the removal percentages of the NiO@HT-derived C composite and HT-derived C declined from 94.64 to 67.70%, and 90.78 to 57.21%, respectively (Table S1, ESI †). This is mainly attributed to the rising repulsion forces between the MR molecules on the surface of the adsorbent and the bulk phase after the initial adsorption.…”

“…This is mainly attributed to the rising repulsion forces between the MR molecules on the surface of the adsorbent and the bulk phase after the initial adsorption. 44,45 Overall, the adsorption capacity of the NiO@HT-derived C composite is much higher than that of the HT-derived C composite, which is mainly due to the higher surface area and porous structures. 46,47 3.2.2.…”

Valorization of Plastic Wastes for the Development of Adsorbent Designed for the Removal of Emerging Contaminants in Wastewater

“…have been removed using adsorbent materials derived from plastic wastes such as cup-stacked CNTs, porous carbon materials, graphene-based materials, carbon nanofibers, etc. [109][110][111].…”