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Dye effluent discharged into the environment can cause serious pollution and damage to the environment. It is crucial to develop adsorbents with excellent adsorption capacity and stable regeneration to meet practical application requirements for the treatment of dye-bearing wastewater. Herein, MoS2 nanoparticles were confined inside a cellulose aerogel to prepare a larger nanocomposite adsorbent (denoted as CAM) for efficient Congo Red (CR) removal from water. Chemical and morphological features of the CAM were examined using XPS, FTIR, XRD, SEM, and HRTEM, while CR adsorption on the nanocomposite was systematically investigated through batch experiments. The CR adsorption process was well described using the Langmuir model, with the maximum adsorption capacity calculated as 334.92 mg/g. The kinetic study illustrated that CR adsorption onto the CAM followed the pseudo-first-order model, and the dye diffusion process into the aerogel was the rate-limiting factor. The hybrid material exhibited excellent CR adsorption selectivity and maintained stable adsorption capacity even in the presence of a high concentration of competitive ions. Importantly, the hybrid aerogel was efficiently regenerated with ethanol and reused for dye adsorption in subsequent batches. Based on all of these results, CAM shows promise for the treatment of dye pollutants. [ABSTRACT FROM AUTHOR]

Excess phosphate in water can cause eutrophication, which must be addressed. Despite many efforts devoted to the adsorptive removal of phosphate from water, the development of new adsorbents with high adsorption capacity is highly desirable. Herein, a novel nanocomposite was proposed for phosphate removal by confining hydrated ferric oxide (HFO) nanoparticles into a cellulose aerogel (CA) network named as HFO@CA. Benefiting from the characteristics of the low density and porous structure of CA, the internal surface of the nanocomposite is more accessible and thus improves the utilization of the HFO nanoparticles. Batch adsorption experiments were carried out to evaluate the phosphate uptake by the prepared adsorbent. The maximum adsorption capacity of HFO@CA occurs at near-acidic pH. With increasing temperature, the composite adsorbent is more favorable for phosphate adsorption. Moreover, the hybrid aerogel exhibited fast kinetic behavior for phosphate removal, which could be accurately depicted by pseudo-second-order model. HFO@CA shows excellent adsorption selectivity in solutions containing competitive anions at higher levels. In addition, five cycles of the phosphate adsorption experiments without obvious capacity loss indicated that HFO@CA has great regenerability. These results demonstrate that HFO@CA has a wide field of application with good prospects in phosphate removal from wastewater, which also provides a new strategy to prepare adsorbents with excellent performance using renewable cellulose resources. [ABSTRACT FROM AUTHOR]

Lifetime is a key index in the evaluation of environmentally functional materials. Although it is well known that adsorption is the first step in photo-catalysis, very little work has been done on the sequential use of materials as both adsorbents and photocatalysts. In this work, two titania-based materials, TiO xerogel and TiO photocatalyst nanoparticles, were fabricated and evaluated as adsorbent and photocatalyst for the remediation of contaminated water with an azo dye, Acid Orange 7 (AO7), as the modeling pollutant. The TiO xerogel showed a high adsorption capacity to AO7 (769 mg/g) and could be regenerated easily with diluted NaOH solution (0.01 mol/L) for several cycles. The exhausted xerogel was calcined at 400 °C for 3 h and used as a photocatalyst for the degradation of AO7. Compared to the nanoparticles directly prepared from fresh TiO xerogel, the TiO nanoparticles from adsorption exhausted xerogel showed a much higher photocatalytic activity upon both UV and visible light irradiation. Thus the titania-based materials were endowed with improved performance as well as prolonged lifetime. [ABSTRACT FROM AUTHOR]

Immobilization of hydrous ferric oxide (HFO) particles inside solid hosts of porous structure is an important approach to improve their applicability in advanced water treatment such as arsenic and heavy metal removal. Here, we fabricated three polystyrene (PS)-based nano-HFOs and explored the effect of host pore structure on the surface chemistry of the immobilized HFOs. Potentiometric titration of the hybrids and surface complexation modeling of their adsorption towards arsenite and arsenate were performed to evaluate the surface chemistry variation of the loaded HFOs. Polymer hosts of higher surface area and narrower pore size would result in smaller particle size of HFOs and lower the value of the point of zero charge. Also, the site density (normalized by Fe mass) and the deprotonation constants of the loaded HFOs increased with the decreasing host pore size. Arsenite adsorption did not change the surface charge of the loaded HFOs, whereas arsenate adsorption accompanied more of the negative surface charges. Adsorption affinity of both arsenic species with three HFO hybrids were compared in terms of the intrinsic surface complexation constants optimized based on the adsorption edges. HFO loaded in polystyrene host of smaller pore size exhibits stronger affinity with arsenic species. [ABSTRACT FROM AUTHOR]