Adsorptive removal of an acid dye by lignocellulosic waste biomass activated carbon: equilibrium and kinetic studies

Chemically prepared activated carbon material derived from palm flower was used as adsorbent for removal of Amido Black dye in aqueous solution. Batch adsorption studies were performed for the removal of Amido Black 10B (AB10B), a di-azo acid dye from aqueous solutions by varying the parameters like initial solution pH, adsorbent dosage, initial dye concentration and temperature with three different particle sizes such as 100 μm, 600 μm and 1000 μm. The zero point charge was pH 2.5 and the maximum adsorption occurred at the pH 2.3. Experimental data were analyzed by model equations such as Langmuir, Freundlich and Temkin isotherms and it was found that the Freundlich isotherm model best fitted the adsorption data and the Freundlich constants varied from (K_F) 1.214, 1.077 and 0.884 for the three mesh sizes. Thermodynamic parameters such as ΔG, ΔH and ΔS were also calculated for the adsorption processes and found that the adsorption process is feasible and it was the endothermic reaction. Adsorption kinetics was determined using pseudo first-order, pseudo second-order rate equations and also Elovich model and intraparticle diffusion models. The results clearly showed that the adsorption of AB10B onto lignocellulosic waste biomass from palm flower (LCBPF) followed pseudo second-order model, and the pseudo second-order rate constants varied from 0.059 to 0.006 (g mg⁻¹ min) by varying initial adsorbate concentration from 25 mg L⁻¹ to 100 mg L⁻¹. Analysis of the adsorption data confirmed that the adsorption process not only followed intraparticle diffusion but also by the film diffusion mechanism.     

Role of black carbon in the distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans in aged field-contaminated soils

Floodplain soils containing elevated levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were collected from several locations along the Tittabawassee River (Michigan, USA). The PCDD/F profiles of these soils exhibited distinct congener patterns consistent with byproducts from either chloralkali manufacturing or chlorophenols productions. Black carbon (BC) particles were isolated for the first time from floodplain soil impacted by PCDD/Fs. Petrographic analysis showed that BC particles, including coal, oxidized coal, metallurgical coke, depositional carbon, coal tar/pitch, cenosphere, and charcoal, comprised approximately 30% by volume of the organic fraction with size range of 250 μm-2000 μm from a typical floodplain soil. The BC particles with anthropogenic origin such as pitch and coke associated with the chloralkali production process served as both the source and subsequent transporter for the highly hydrophobic PCDD/Fs. These anthropogenic BC particles were enriched with high levels of PCDFs, containing approximately 1000-fold the concentration found in the bulk soil. The strong association of PCDD/Fs with anthropogenic BC directly impacts the physicochemical and biological availability thus the risk associated with these hydrophobic organochlorines in soils and sediments.     

Development of a combined isotopic and mass-balance approach to determine dissolved organic carbon sources in eutrophic reservoirs

A combined mass-balance and stable isotope approach was set up to identify and quantify dissolved organic carbon (DOC) sources in a DOC-rich (9 mg L⁻¹) eutrophic reservoir located in Western France and used for drinking water supply (so-called Rophemel reservoir). The mass-balance approach consisted in measuring the flux of allochthonous DOC on a daily basis, and in comparing it with the effective (measured) DOC concentration of the reservoir. The isotopic approach consisted, for its part, in measuring the carbon isotope ratios (δ¹³C values) of both allochthonous and autochthonous DOC sources, and comparing these values with the δ¹³C values of the reservoir DOC. Results from both approaches were consistent pointing out for a DOC of 100% allochthonous origin. In particular, the δ¹³C values of the DOC recovered in the reservoir (−28.5 ± 0.2‰; n = 22) during the algal bloom season (May-September) showed no trace of an autochthonous contribution (δ¹³C in algae = −30.1 ± 0.3‰; n = 2) being indistinguishable from the δ¹³C values of allochthonous DOC from inflowing rivers (−28.6 ± 0.1‰; n = 8). These results demonstrate that eutrophication is not responsible for the high DOC concentrations observed in the Rophemel reservoir and that limiting eutrophication of this reservoir will not reduce the potential formation of disinfection by-products during water treatment. The methodology developed in this study based on a complementary isotopic and mass-balance approach provides a powerful tool, suitable to identify and quantify DOC sources in eutrophic, DOC-contaminated reservoirs.     

基于活性污泥的厨余垃圾厌氧发酵产酸研究

以厨余垃圾和活性污泥为原料,考察了不同接种比例对厌氧发酵产物的挥发性脂肪酸产量、pH值和COD去除率的影响.结果表明,当厨余垃圾和活性污泥接种比例为4∶1时,挥发性脂肪酸产量在第3天达到最大值为42.7 g/L,产率提高了40%,COD去除率达到了35.6%,pH值没有发生较大的差异,其变化幅度在4～6之间.     

活性污泥与生物膜复合工艺处理石化废水的研究

实验研究了活性污泥与生物膜复合工艺(HP)对石化废水的处理效果,并与活性污泥工艺(ASP)进行对比研究.结果表明,HP对石化废水中COD的去除效果略好于ASP,而对NH3-N的去除效果明显优于ASP.另外,两种工艺对硫化物和油的去除效果类似.提高进水负荷时,HP表现出较强的耐冲击负荷能力.以2L/h连续运行时,石化废水...     

给水曝气生物滤池内置粉末活性炭复合净水效果的研究

在给水曝气生物滤池内置粉末活性炭,对比分析其对各工艺单元水质净化效果的影响,确定给水曝气生物滤池内置粉末活性炭的作用与最佳投加量,研究表明,给水曝气生物滤池将活性炭截留在滤池内,大幅度提高了粉末活性炭利用率,部分未饱和粉末活性炭通过反冲洗排入后续常规处理系统,作为生物载体仍能够进一步发挥生物强化作用。当粉末活性炭的投加量为8 mg/L时,砂滤出水氨氮、CODMn、浊度和色度均值分别为：0.02 mg/L,1.82 mg/L0,.46 NTU和6度,去除率分别达到99.6%、71.2%、99.1%和80.6%,出水指标达到《生活饮用水卫生标准（》GB5749-2006）和《饮用净水水质标准（》CJ94-2005）规定的标准。与常规工艺相比,投加量降低了20%～60%。     

PVA降解混合菌系生长和产酶的营养条件分析

研究碳源、氮源以及不同金属离子对PVA降解混合菌系生长和产酶的影响。结果表明,混合菌系生长过程中无机氮源优于有机氮源;补充碳源可促进混合菌系的生长,但酶活比不添加时稍有降低。金属离子对酶活影响的正交实验表明Mg2＋浓度影响最大,其次是Fe2＋和K＋浓度,Ca2＋、Mn2＋、Zn2＋和Cu2＋浓度影响较小;最佳浓度分别为Mg2＋0.05 g/L、Fe2＋0.04 g/L、K＋2 g/L和Ca2＋0.05 g/L。     

活性炭纤维(ACF)应用于有机废气回收和净化的进展

活性炭纤维(ACF)有比普通活性炭吸附量大、吸附和脱附速度快等优点,因此应用于有机废气的回收和净化,具有良好的经济、环境和社会效益。文中介绍了ACF的微观结构、表面化学以及吸附性能,并综述了近年来ACF在有机废气回收和治理方面的国内概况。     

季铵化合物对好氧活性污泥吸附Ni2+的影响研究

以季铵化合物中最具潜在影响力、毒性较大的苄基季铵盐(BAC)为模型物,进行了BAC对好氧活性污泥吸附Ni2+的影响研究.结果表明,当反应液初始pH≤3时,不同浓度的BAC对好氧活性污泥吸附Ni2+的影响较小,当初始pH在3～9时,不同浓度的BAC对Ni2+吸附的抑制影响顺序为100 mg/L＞20 mg/L＞0 mg/...     

Modifications of black carbons and their influence on pyrene sorption

Sorption of pyrene on black carbons (BCs) obtained by heating sawdust at two temperatures (400 and 700 °C, denoted as 400BC and 700BC, respectively), as well as on modified BCs (via oxidation, oximation, and hydrolysis) was studied to investigate the role of BC structural characteristics in sorption of hydrophobic organic compounds. Pyrene was bound strongly by 700BC and 400BC, with organic carbon normalized distribution coefficients (K_oc) of 10^5.04-10^5.86 and 10^4.65-10^5.16, respectively, at equilibrium pyrene concentrations of 10-100 μg L⁻¹. Both chemical composition and pore distribution of the two BCs changed after modifications, which led to changes in their sorption characteristics for pyrene. After modifications, the linearity of pyrene sorption isotherm increased for 700BC but decreased for 400BC. For 700BC, both oxidation and oximation reduced pyrene sorption, with K_oc decreasing by 69.1-73.7% and 18.7-33.9%, respectively, whereas hydrolysis did not exert a significant influence. For 400BC, oxidation and hydrolysis reduced K_oc by 2.28-25.9% and 29.2-33.9%, respectively, while oximation increased K_oc. In most cases, the change in sorption capacity could be explained by the changes in C content and type, polarity, surface area, and micropore volume of the BCs; however, the role of conformation (the accessibility to sorption sites) could not be ignored.