有机改性沸石对废水中酸性靛蓝的吸附研究

用十六烷基三甲基溴化铵和十二烷基硫酸钠复合改性沸石,通过红外吸收光谱(IR)对改性前后的沸石结构进行表征,采用分光光度法分析改性沸石对酸性靛蓝的吸附性能及影响因素。结果表明,改性沸石的吸附性能明显增强。在优化试验条件下对浓度为200 mg/L的酸性靛蓝的最大吸附量和脱色率分别为66.56mg/g和99.85%。改性沸石对酸性靛蓝的吸附规律较好的符合Langmuir吸附等温式,吸附过程符合准二级动力学方程。     

拜耳法赤泥质陶粒滤料处理含铜废水

以自制拜耳法赤泥质陶粒滤料为吸附剂,进行了模拟废水中铜离子吸附效果和吸附饱和陶粒再生的研究。结果表明,拜耳法赤泥质陶粒滤料对废水中铜离子具有较好的吸附效果和耐久性;吸附饱和后的陶粒在pH=3的硝酸溶液中静态洗脱3次即可恢复至新鲜陶粒的吸附水平;拜耳法赤泥质陶粒用于废水中铜离子的吸附无论从技术上、经济上还是从二次资源的再利用上均具有显著优势,适合大规模推广应用。     

磁性衬板磁场强度对吸附层厚度影响的数值模拟

利用Ansoft有限元软件详细分析了金属磁性衬板表面磁感应强度、磁场力分布以及磁感应强度对吸附层厚度的影响。研究结果表明,磁性衬板表面的磁感应强度和受力分布具有相似的形貌,呈现两极中间强、极中心弱的特点;磁感应强度与距磁块表面距离呈e指数衰减关系;拟合公式和数据点拟合程度较好。     

不同价态杂质离子对黄铜矿浮选的影响机理研究

随着淡水资源的匮乏,选矿回水逐渐用于浮选黄铜矿,回水中存在的杂质离子会影响黄铜矿浮选指标。因此,以Na+、Ca2+、Al3+为例,研究不同价态的杂质离子对黄铜矿浮选的影响及其作用机理。试验结果表明:NaCl对黄铜矿可浮性有较强的促进效果,高浓度CaCl2对黄铜矿可浮性有明显抑制作用,而AlCl3对黄铜矿可浮性有一定抑制作用,但影响不显著。黄铜矿表面接触角、Zeta电位及物相图表明:高浓度NaCl阻碍气泡兼并,增加矿浆起泡性,压缩矿物表面双电层,减小气泡到达矿物表面的能量壁垒,促进气泡-颗粒的附着,提高黄铜矿可浮性;CaCl2对黄铜矿浮选的抑制作用是在溶液中形成了亲水的Ca2+羟基络合物(Ca(OH)+),通过很强的亲和力吸附于黄铜矿表面,降低了黄铜矿表面的Zeta电位负值,进而降低其表面疏水性,抑制黄铜矿浮选;AlCl3对黄铜矿浮选的抑制作用主要是因为形成的亲水氢氧化铝沉淀附着于黄铜矿表面,导致黄铜矿表面疏水性减弱,但由于形成沉淀浓度较低,对黄铜矿表面电位和浮选作用有限。     

Hydrogen storage comparison of M doped vanadium oxide nanotubes (M = Mo,Zr and W): A molecular simulation study

Zr, Mo and W doped Vanadium oxide nanotube were considered as remarkable materials for hydrogen storage applications. Monte Carlo molecular simulation was performed to study the adsorption behavior of hydrogen molecules on Vanadium oxide nanotubes (VONTs). The effects of temperature, pressure and mole percent of hydrogen on adsorption capacity of VONTs were investigated to provide deep insight of adsorption behavior. The results represented that hydrogen adsorption is an increasing function of pressure and at about 50 MPa all three metal doped VONT has maximum hydrogen capacity. At 5 MPa and room temperature, the hydrogen capacities of Mo, W and Zr doped VONTs were 1.39, 0.88 and 1.43 w% respectively. With temperature increment up to room temperature, more reduction in initial hydrogen capacity were observed in Mo and Zr doped VONTs.Evaluating hydrogen adsorption of Zr doped VONT from pure and hydrogen /nitrogen mixtures at 300 K indicated that under 2 Mpa, modifications in adsorption capacities were insignificant after N2 addition to the environment. Therefore, Zr doped VONT in hydrogen /nitrogen mixture environment can act as a capable adsorbent for Hydrogen storage system in comparison with Mo and W doped VONTs.     

Hydrogen adsorption on natural and sulphuric acid treated sepiolite and bentonite

In this study, hydrogen (H₂) adsorption on sepiolite and bentonite and those of acid treated forms were studied at 77 K using volumetric apparatus up to 100 kPa. Both clay minerals were treated with 100 ml of 0.5, 1.0, 2.0 and 4.0 M H₂SO₄ solutions at 80 °C for 5 h. Differences in the structures of the sepiolite and bentonite samples before and after the acid treatments were determined by XRD, XRF, TG, DTA and N₂ adsorption methods. The level of H₂ adsorption of original and acid treated sepiolite samples (1.332–2.252 mmol/g) was higher than those of the bentonite samples (0.341–1.003 mmol/g). The variation in the H₂ adsorption capacities during the acid treatment was also discussed.     

Determination of 4-nonylphenol and 4-tert-octylphenol compounds in various types of wastewater and their removal rates in different treatment processes in nine wastewater treatment plants of Iran

Alkylphenols(APs), considered as xenoestrogenic compounds, mainly exist as 4-nonylphenol(4-NP) and 4-tertoctylphenol(4-t-OP) in environments. The high stability and accumulation of APs in aquatic systems have caused endocrine disruption. In this study we measured APs in the wastewater influent and effluent samples, from the urban, rural, livestock, commercial and hospital wastewater treatment plants(WWTPs) in Iran. Dispersive liquid–liquid microextraction(DLLME) combined with gas chromatography–mass spectrometry(GC–MS) was used for the extraction and determination of 4-NP and 4-t-OP. In these treatment plants, various processes such as activated sludge, aerated lagoon, moving bed biofilm reactor and activated sludge along with wetland were applied. The highest concentration of 4-NP and 4-t-OP was observed in commercial and livestock sewages. The activated sludge along with wetland and then the MBBR process showed the highest removal rates of pollutants. The rates of biodegradability and accumulation in sludge were determined and also the specific adsorption coefficient Kdand the organic carbon–water partition coefficient kOCof the sludge for APs were calculated.     

Biodegradation of natural and synthetic estrogens in moving bed bioreactor

Estrogen hormones as a group of endocrine disruptive compounds(EDC) can interfere with endocrine system in humans and animals. The goal of this study was to investigate the elimination rate of Estrone(El), 17β-estradiol(E2) and 17α-ethinyl estradiol(EE2) in Moving Bed Bioreactor(MBBR). These analytes extracted by Dispersive Liquid-Liquid Microextraction(DLLME) technique, followed by derivatization, and detected by GC/MS. Estrogen removal efficiency in MBBR improved at high solid retention times(SRTs), which notion is owing to development of nitrification. Estrogen specific removal rate was between 0.22-1.45 μg·(g VSS)~(-1)·d~(-1) for natural and synthetic hormones. The adsorption rate was 0.9%-3.2%, 0-1.3%, and 0.7%-5.7% for El, E2, and EE2, respectively. In addition, the biodegradation rates were more than 95% for these compounds. These results illustrated that in MBBR,the biodegradation and the adsorption to biomass are considered as two significant routes for elimination of estrogenic compounds. As a whole, the deterioration rate of estrogens enhanced by MBBR compared to other biological wastewater treatment processes such as conventional activated sludge.     

Fabrication of chitosan microspheres for efficient adsorption of methyl orange

In this article, morphology, structure and size controllable chitosan microspheres with high mechanical strength were synthesized by microfluidic technology combining chemical crosslinking and used as an adsorbent for methyl orange. The synthesized adsorbents were characterized using scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR), and an Energy Dispersive Spectrometer(EDS). The effect of pH revealed that the adsorption process depended on pH and the pH variation of methyl orange solution after adsorption indicated that adsorption capacity was affected through the associated role of chitosan nature and pH variation. Experimental results suggested that the as-prepared chitosan microspheres were controlled within a narrow size distribution(coefficients of variation is 1.81%), whose adsorption capacity reached to 207 mg·g~(-1) and mechanical strength was suitable to resist forces. In addition, the adsorption isotherm was well fitted with the Langmuir model, and the adsorption kinetic was best described by the pseudo-second-order kinetic model.The high performance microfluidic-synthesized chitosan microspheres have promising potentials in the applications of removing dyes from wastewater.     

Facile synthesis of hierarchically porous carbons by controlling the initial oxygen concentration in-situ carbonization of ZIF-8 for efficient water treatment

The state-of-the-art approaches for adjusting the structural characteristics of porous carbons are the after-treatments, which are complicated and time consuming. In this work, a facile approach was developed, i.e., controlling the initial oxygen concentration in-situ during the direct carbonization of zeolitic imidazole framework-8 (ZIF-8), to adjust the pore structure and prepare hierarchically porous carbons. The introduction of oxygen can significantly affect the crystalline and pore structures of porous carbons, and promote the pore widening and the formation of mesopores. An appropriate initial oxygen concentration can notably enhance the surface area and mesopore volume of porous carbon, and then improve the adsorption capacity toward methylene blue (MB) dye from water by 3.4 times. The developed approach is more efficient at lower carbonization temperature. Moreover, the introduction of oxygen can increase the ratio of HOCO groups on the carbon surface, leading to enhanced interaction with MB molecules and higher adsorption capacity toward MB. The as-prepared porous carbons exhibit superior adsorption capacities toward MB dye as compared to the reported ZIF-8 derived carbons. These findings would aid the development of porous carbon materials with high performance.