Adsorption Kinetics and Breakthrough of Carbon Dioxide for the Chemical Modified Activated Carbon Filter Used in the Building

Fabrication of Polyethyleneimine-Functionalized Magnetic Cellulose Nanocrystals for the Adsorption of Diclofenac Sodium from Aqueous Solutions

Diclofenac sodium (DS), one of the most used non-steroidal anti-inflammatory drugs worldwide, is often detected in wastewater and natural water. This drug is ecotoxic, even at low concentrations. Therefore, it is essential to fabricate low-cost adsorbents that can easily and effectively remove DS from contaminated water bodies. In this study, a polyethyleneimine (PEI)-modified magnetic cellulose nanocrystal (MCNC) was prepared with a silane coupling agent as a bridge. TEM, FTIR, XRD, and VSM were used to demonstrate the successful preparation of MCNC-PEI. This composite adsorbent exhibited efficient DS removal. Furthermore, the adsorption performance of MCNC-PEI on DS was optimal under mildly acidic conditions (pH = 4.5). Adsorption kinetics showed that the adsorption process involves mainly electrostatic interactions. Moreover, the maximum adsorption capacity reached 299.93 mg/g at 25 °C, and the adsorption capacity only decreased by 9.9% after being reused five times. Considering its low cost, low toxicity, and high DS removal capacity, MCNC-PEI could be a promising adsorbent for treating DS-contaminated water.

Nature-Based Solution for Reducing CO2 Levels in Museum Environments: A Phytoremediation Study for the Leonardo da Vinci’s “Last Supper”

This work investigates the possibility of implementing a nature-based solution (NBS) based on the photosynthetic process of Laurus nobilis L. (common laurel), for reducing peak CO2 concentrations in an air-tight museum environment, namely the Refectory of the Santa Maria delle Grazie Church (Milan, Italy), home of Leonardo da Vinci’s painting “Last Supper”. The phytoremediation potential of laurel plants was evaluated at CO2 ≅ 1000 ppm under controlled environmental conditions. Furthermore, light-saturated net assimilation (Pnmax) was measured at two CO2 concentrations (380 and 1000 ppm) during the growing season. Steady-state gas exchanges were not affected by elevated CO2 in the short-term, while Pnmax was significantly increased, also showing higher values in spring and autumn, and a reduction during summer. Our estimated CO2 removal rates indicate that, in order to control visitors’ respiratory CO2 emissions in view of an increase in visitor numbers in the Refectory, a possible NBS in the form of an external greenhouse, connected to the HVAC system of the museum, should allocate from 58 to 112 young laurel plants, depending on their seasonal phytoremediation capacity. These results, although preliminary, allow to hypothesize the possibility of controlling CO2 indoors through a combination of traditional air-cleaning systems and a properly designed NBS, thus increasing the sustainability of air-tight museum environments.

Characterization and Modelling Studies of Activated Carbon Produced from Rubber-Seed Shell Using KOH for CO2 Adsorption

Global warming due to the emission of carbon dioxide (CO2) has become a serious problem in recent times. Although diverse methods have been offered, adsorption using activated carbon (AC) from agriculture waste is regarded to be the most applicable one due to numerous advantages. In this paper, the preparation of AC from rubber-seed shell (RSS), an agriculture residue through chemical activation using potassium hydroxide (KOH), was investigated. The prepared AC was characterized by nitrogen adsorption–desorption isotherms measured in Micrometrices ASAP 2020 and FESEM. The optimal activation conditions were found at an impregnation ratio of 1:2 and carbonized at a temperature of 700 °C for 120 min. Sample A6 is found to yield the largest surface area of 1129.68 m2/g with a mesoporous pore diameter of 3.46 nm, respectively. Using the static volumetric technique evaluated at 25 °C and 1.25 bar, the maximum CO2 adsorption capacity is 43.509 cm3/g. The experimental data were analyzed using several isotherm and kinetic models. Owing to the closeness of regression coefficient (R2) to unity, the Freundlich isotherm and pseudo-second kinetic model provide the best fit to the experimental data suggesting that the RSS AC prepared is an attractive source for CO2 adsorption applications.

Characterization and adsorption capacity of potassium permanganate used to modify activated carbon filter media for indoor formaldehyde removal

This study examined the effect of potassium permanganate (KMnO₄)-modified activated carbon for formaldehyde removal under different face velocities and different initial formaldehyde concentrations in building environment. We chose the coconut shell activated carbon due to their high density and purity. Moreover, they have a clear environmental advantage over coal-based carbons, particularly in terms of acidification potential. The chemical properties were characterized by FTIR to show the functional groups, EDS to calculate each component of their energy bands to know how the ratio is. Also, the morphology of the surface was examined with scanning electron microscopy (SEM). The BET determines specific surface area, pore size, and pore volume. It was found that where the initial formaldehyde concentration and the face velocity are low, adsorption capacity is high. The adsorption isotherms of formaldehyde on modified activated carbon are well fitted by both Langmuir and Freundlich equations. The rate parameter for the pseudo-first-order model, pseudo-second-order model, and intraparticle diffusion model was compared. The correlation coefficient of pseudo-second-order kinetic model (0.999 > R² > 0.9548) is higher than the coefficient of pseudo-first-order kinetic model (0.5785 < R² < 0.8755) and intraparticle diffusion model (0.9752 < R² < 0.9898). Thus, pseudo-second-order kinetic model is more apposite to discuss the adsorption kinetic in this test, and the overall rate of the modified activated carbon adsorption process appears to be influenced by more than one step that is both the intraparticle diffusion model and membrane diffusion.