Porous polymer magnetic adsorbents for dye wastewater treatment.

Dye wastewater discharged from industries has caused serious environmental problems. The recent decade has witnessed adsorption technology emerging as an advanced dye wastewater treatment method with great potential Therefore, we fabricated two kinds of magnetic porous adsorbents (HSF and HSVF) with different specific surface areas and activity sites. Both of which exhibit excellent performance with remarkable dye adsorption capacities, especially HSVF. We further investigated their adsorption kinetic and isotherm in detail. Therein, HSVF showed a nice desorption capacity, and it could be recycled rapidly by magnetism, which exhibited the advantages of effective, easy operation, and low cost. In addition, their adsorption kinetic and isotherm were further studied and compared in detail. The results revealed that introducing strong active sites could improve both the adsorption capacity and rate effectively even though sacrificing part of specific surface areas, indicating that active sites might play a dominant role during the dye adsorption process.

Ultrahigh-Porosity MgO Microparticles for Heat-Energy Storage.

Continuous industrial development has increased the demand of energy. Inevitably, the development of energy sources is steadily progressing using various methods. Rather than establishing a new energy source, a system for storing waste heat generated by industry has now been accepted as a useful strategy. Among such systems, the hydration and dehydration reactions of MgO/Mg(OH)2  are eco-friendly, have relatively low toxicity and risk, and have a large reserves. Therefore, it is a promising candidate for a heat-storage system. In this study, ultrahigh-porosity particles are used to maximize the heat-storage efficiency of pure MgO. Due to its large surface area, the heat storage rate is 90.3% of the theoretical value and the reaction rate is very high. In addition, as structural collapse, likely to be caused by volume changes between reactions, is blocked as the porous region is filled and emptied, the cycle stability is secured. Ultrahigh-porosity MgO microparticles can be used to build eco-friendly heat-storage systems.

Construction of Oxygen-Rich Carbon Foams for Rapid Carbon Dioxide Capture.

As carbon dioxide (CO2) adsorbents, porous materials with high specific surface areas and abundant CO2-philic groups always exhibit high CO2 capacities. Based on this consensus, a category of oxygen-rich macroporous carbon foams was fabricated from macroporous resorcinol-formaldehyde resins (PRFs), which were obtained via an oil-in-water concentrated emulsion. By the active effect of potassium hydroxide (KOH) at high temperatures, the resultant carbon foams (ACRFs) possessed abundant micropores with rich oxygen content simultaneously. At the same time, most of the ACRFs could retain the marcoporous structure of their precursor. It is found that porosity of ACRFs was mainly determined by carbonization temperature, and the highest specific surface areas and total pore volume of ACRFs could reach 2046 m2/g and 0.900 cm3/g, respectively. At 273 k, ACRFs showed highest CO2 capacity as 271 mg/g at 1 bar and 91.5 mg at 15 kPa. Furthermore, it is shown that the ultra-micropore volume was mainly responsible for the CO2 capacities of ACRFs at 1 bar, and CO2 capacities at 15 kPa were mainly affected by the oxygen content. It is also found that the presence of macropores would accelerate ACRFs adsorbing CO2. This study provides ideas for designing a porous CO2 adsorbent.

Towards Macroporous α-Al2O3-Routes, Possibilities and Limitations.

This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16-24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

Surface characteristics and potential ecological risk evaluation of heavy metals in the bio-char produced by co-pyrolysis from municipal sewage sludge and hazelnut shell with zinc chloride.

Municipal sewage sludge (MSS) and hazelnut shell were used for co-pyrolysis by chemical activation with ZnCl2. The surface characteristics and potential ecological risk evaluation of heavy metals in the bio-char produced by co-pyrolysis were analyzed by surface analyzer and BCR sequential extraction. When raw materials with ZnCl2 (3mol/L) were co-pyrolyzed at 500°C for 90min, specific surface area of the bio-char is 598.73m2/g, and iodine absorption number is 607.85mg/g. For microcosmic surface of the bio-char, the ratio of micropore area is stabilized from 0.74 to 0.80 of the total specific surface area, and hazelnut shell is effective to generate microporous construction. For the migration and transformation behavior of heavy metals, pyrolysis promoted mobile fraction (F1 and F2) to stable fraction (F3 and F4) with increasing pyrolysis temperature. The potential ecological risk of heavy metals transforms from considerable risk to low risk after pyrolysis at 500°C.

Occurrence and partition ratios of radiocesium in an urban river during dry and wet weather after the 2011 nuclear accident in Fukushima.

After the 2011 nuclear accident in Fukushima, radiocesium was released from the Fukushima Dai-ichi Nuclear Power Plant and contaminated waters in urban areas near Tokyo. By intensive field monitoring during 3 years, this study investigated the temporal trends and the occurrence of radiocesium during dry and wet weather, and analyzed the variations in radiocesium during rainfall events and factors controlling them. Concentrations of particulate radiocesium decreased rapidly from May 2012 to March 2013 and reached an equilibrium in 2014. Concentrations of particulate (137)Cs during wet weather were almost double those during dry weather in the same period. In contrast to the small variations in (137)Cs concentrations in the particulate phase on a suspended solids (SS) weight basis during events, those in the dissolved phase on a liquid-volume basis fluctuated greatly, resulting in variations in the partition coefficient (apparent Kd). The apparent Kd of (137)Cs during wet weather ranged from 30,000 to 150,000 L kg(-1) and showed a significant negative correlation with SS concentrations during wet weather. Specific surface area in solids contributed to the variations in apparent Kd.