Insight into the removal process mechanism of pharmaceutical compounds and dyes on plasma-modified biomass: the key role of adsorbate specificity

Preparation of pyrolytic coke/uio-66 composite and its effectiveness for removing mono-ethylene glycol (MEG) from aqueous environments

In the present study, the potential of pyrolytic coke (PC) and PC modified with UiO-66 nanoparticles as adsorbents for removing mono-ethylene glycol (MEG) from aqueous solutions was studied. Different experimental techniques were used to investigate the properties of adsorbents. The modification of the PC surface (6.91 m2/g) with UiO-66 significantly enhanced the specific surface area of the PC/UiO-66 composites, increasing it to 379.31 m2/g. Maximum MEG adsorption using PC (84.21%) and PC/UiO-66 (96.75%) was recorded at pH equal to 5 and 7, MEG quantity of 100 mg/L, temperature of 25 °C, adsorbent dosage of 1 g/L, and treatment time of 120 min, respectively. The Langmuir isotherm adsorption capacities for MEG removal using PC and PC/UiO-66 were determined to be 265 mg/g and 291 mg/g, respectively. The KF and AT values for the MEG adsorption were obtained at 128.1 mg/g (L/mg)1/n and 11.05 L/g, indicating the more pronounced affinity of the PC/UiO-66 towards MEG than the PC sample. The enthalpy, entropy, and Gibbs free energy were determined to be negative; thus, the MEG adsorption was exothermic and spontaneous in the range of 25-50 °C. The results demonstrated that the experimental data adheres to a pseudo-first-order kinetic. The adsorbents were recycled up to five stages, and the results showed that after five cycles, no significant decrease in the adsorption efficiency occurred, making them suitable for repeated utilization in the adsorption process.

Egg-derived porous plasma modified clay composite for wastewater remediation

Clays are often envisaged as an alternative to activated carbon for wastewater pollutant adsorption. However, conclusive results have only been obtained for clays heavily chemically modified. In this study, a greener approach is proposed to improve the retention capacity of clays. It consists in mixing clay (C) with eggshell (ES) and calcine, and then exposing to gliding arc plasma (ESC-800/PL). The resulting materials were characterized by nitrogen physisorption, FTIR, XRD, TGA/DTG, and point of zero charge analyses. The preparation gives porous platelet agglomerates resulting from the kaolinite-metakaolinite transition, thereby increasing their internal specific surface area and capacity to retain pollutants. This granular distribution is kept stable by partial pozzolanic reactions avoiding deagglomeration. The specific surface area and total pore volume increased respectively from 14 m² g^-1 and 0.049 cm³ g^-1 to 89 m² g^-1 and 0.061 cm³ g^-1 leading to an enhanced removal efficiency of Fast Green and Orange G dyes from polluted water. The maximum adsorption capacity occurred at 298 K attaining values of 32.34 and 14.78 mg g^-1 for OG and FG, respectively. The pH plays a crucial role in the maximum sorption of dyes, and the experimental data were successfully adjusted to pseudo-first-order kinetic and Liu isotherm model.