An eco-friendly cellulose support functionalized with tin titanate nanoparticles for the fast removal of clonazepam drug from the drinking water: adsorption mechanisms.

This research studied the performance of tin titanate (SnTiO3, SnT) and cellulose-based composites for the removal of clonazepam (CZP) drug by physical adsorption. The cellulose was extracted from a plant named tithonia tubaeformis, which is considered as weed in the crop fields of Mexico. The analysis by microscopy revealed that the SnTiO3 powders are formed by a mixture of coalesced grains and nanotubes with lengths in the range of 97-633 nm. Furthermore, the X-ray diffraction analysis indicated that the SnT powders present a mixture of cassiterite and rutile phases. Experiments for the CZP removal from drinking water were carried out, and several parameters such as initial drug concentration (1-10 mg/L), amount of SnT adsorbent per liter of contaminated solution (10-50 mg/L), and pH (3-10) were varied in order to study their influence on the CZP removal percentage. Essentially, we found that the SnT dosage of 50 mg/L produced the most efficient and fastest CZP removal, since 94.3% of CZP was removed after only 10 min of reaction. Moreover, a piece of cellulose (Cell) was decorated with 50 mg of SnT powder to form the Cell+SnT composite, and this was able to remove a maximum of 80.5% of CZP after 180 min of reaction. If the amount of SnT powder deposited on the Cell+SnT composite is raised up to 100 mg, the composite can remove 95.5% of CZP. The adsorption capacity was also calculated for the SnT powders and Cell+SnT composite and found that it was 6.3 times higher for the SnT powders. Furthermore, the Raman spectra recorded for the Cell+SnT composites demonstrated the presence of surface defects, which acted as adsorption centers for the CZP molecules. The results of this investigation demonstrate that eco-friendly and low-cost floatable composites can be used for the removal of pharmaceutical contaminants, which is an advantage over adsorbent powders.

Novel sustainable composites made of car's waste and sodium titanate for the efficient photocatalytic removal of the bromophenol blue dye: study under solar and UV-Vis light.

In this research, W-doped sodium nanotube titanate (NaTNT) nanoparticles were used for the photocatalytic degradation of the bromophenol blue (BPB) dye. The NaTNT powder was mixed with car's tire powder (TP) to enhance its light absorption or was supported on recycled car's air filters (AFs) to facilitate its removal from the cleaned water after the degradation of the BPB. The SEM analysis indicated that the NaTNT nanoparticles and the TP had sizes in the range of 150-325 nm and 8-37 µm, respectively. Both powders were also studied by X-ray diffraction and found that the sodium titanate corresponds to the Na2Ti6O13 with monoclinic phase, while the TP is formed by rubber, silicon, ZnS, and ZnO. The photocatalytic activity of the NaTNT powder was evaluated for the degradation of BPB dye (20 ppm) and obtained a maximum degradation of 95 and 80% under UV-Vis and natural solar light, respectively, after 4 h of irradiation. For the NaTNT + TP composite mixture, the maximum degradation was 87 and 68% under UV-Vis and solar light, respectively. The NaTNT and NaTNT + TP powders were supported on the AFs to form the AF + NaTNT and AF + NaTNT + TP composites. Those ones produced maximum degradation of 86% and 74% (under UV-Vis light), respectively. Besides, several initial pHs were tested for the contaminated water and determined that the maximum degradation of BPB (93-95%) is reached for the pHs of 3 and 7. Reuse experiments (3 cycles) revealed that the diminution of the BPB degradation percentage was 23% and 20% for the NaTNT and NaTNT + TP powders, respectively. Overall, it was demonstrated that the wasted car's air filters can be used as a support for photocatalytic powders, and this combination of AF + powder degrades the BPB with high efficiency.