RESUMEN
Given the critical importance, resource limination and environmental toxicity of phosphorus, the study of phosphorus recovery and utilization is extremely urgent. This paper utilized unmodified oyster shell powder (OSP) and cotton fibers as raw materials to prepare OSP-loaded cellulose gel beads (OSP@Gel) through the fiber-dissolving capability of LiBr·3H2O molten salt, for phosphate recovery from water. The surface microstructure and chemical properties of OSP@Gel were characterized by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), confirming the loading of OSP onto the gel matrix. The phosphorus adsorption capacity of a single OSP@Gel bead could reach up to 8.80 ± 0.32 mg at the optimal OSP doping amount of 1.0 g and optimal pH of 5.0. Kinetic and isotherm analyses revealed that the experimental data fit the PSO model and the Langmuir model. Thermodynamic analysis suggested that the phosphate adsorption was endothermic. Combined results from SEM and XPS analyses indicated that the adsorption of phosphate by OSP@Gel was chemical, with adsorption rate controlled by both liquid film diffusion and intraparticle diffusion. The high phosphate adsorption capacity, good mechanical stability in water, and easy degradability in plant soil provide OSP@Gel beads with great potential for phosphate recovery.
RESUMEN
This study investigated the association between internet use as a novel type of social engagement and the health of older adults, and evaluated the role of online versus offline social activities through nationally representative samples. Participants aged ≥ 60 in the datasets from the Chinese sample of the World Value Survey (NSample 1 = 598) and the China Health and Retirement Longitudinal Study (CHARLS, NSample 2 = 9434) were selected. Correlation analysis presented the positive relationships between internet use and self-reported health in both Sample 1 (r = 0.17, p < 0.001) and Sample 2 (r = 0.09, p < 0.001). In addition, the relationships between internet use and both self-reported health and depression (r = -0.14, p < 0.001) were stronger than the correlation between offline social activities and health outcomes in Sample 2. After accounting for the frequency of traditional social activities, regression analysis revealed the relationship between internet use and higher self-reported health (ßSample 1 = 0.16, p < 0.001; ßSample 2 = 0.04, p < 0.001) and lower depressive symptom scores (ß = -0.05, p < 0.001) This research contributes to the existing body of literature on the favorable relationship between social engagement and health outcomes among Chinese older adults. Additionally, it identifies the social benefits of internet use for health promotion among older adults.