改性植物生物炭去除水中四环素类抗生素的研究进展

四环素类抗生素滥用和缺乏有效去除技术导致广泛残留并诱导产生耐药细菌,已成为世界环境问题之一.植物生物炭具有来源广、成本低、易制备、资源有效利用和环境友好等优点,在环境修复领域,特别是抗生素污染物去除方面备受关注.本文综述了改性植物生物炭对四环素类抗生素的去除效果,讨论环境因素对改性生物炭性能的影响并深入探讨去除机制,分...     

基于生物炭的高级氧化技术去除水中化学品类新污染物研究进展

化学品类新污染物种类繁多,对自然生态环境和人类健康存在严重风险,是新污染物治理的主要对象。由于常规水处理工艺对新污染物的去除能力有限,如何发展绿色、经济、高效和安全稳定的净水技术成为新污染物管控的重要课题。生物炭因其丰富的表面结构与性质,具有优异的吸附和催化能力。近年来,众多科研工作者开展了基于生物炭的高级氧化技术(AOPs)去除新污染物的效能和机制研究。本文聚焦主要的化学品类新污染物,分析了生物炭结构与去除新污染物功能间的关系,综述了近年来生物炭在光催化氧化、类芬顿氧化和过硫酸盐催化氧化中的应用,并探讨了水环境条件(如pH值、阴离子和有机物等)对反应体系的影响,最后对未来相关研究中值得关注和深入探索的问题进行了总结与展望。     

改性生物炭对废水中锑的去除研究进展

废水锑排放限值日趋严格,迫切需要高效低成本的废水锑去除技术.本文介绍了含锑废水较为成熟的处理技术和工艺,然后结合生物炭的制备和特点综述了改性生物炭技术应用于废水中锑的去除治理所具有的明显优势和现阶段所取得的研究成果,为改性生物炭技术用于废水中锑的去除应用和推广提供一定的参考.     

基于生物炭的高级氧化技术降解水中有机污染物

碳基材料催化剂因具有良好的催化性能,同时可避免金属催化剂的重金属沥出造成的二次污染问题,常被应用于高级氧化领域。其中,以废弃生物质为原材料热解产生的生物炭,不仅具有催化潜力,还具有低成本和绿色环保等优势,被广泛用于活化过氧化氢、过一硫酸氢盐和过二硫酸盐等过氧化物降解水中有机污染物。本文介绍了生物炭的前体种类和制备方法、阐述了二者对生物炭活化能力的影响,总结了生物炭活化过氧化物的机理,分析了水质对降解污染物的影响,综述了生物炭的改性、循环使用及再生,指出了这一技术存在的问题并对后续研究进行了展望。     

镁改性泡沫炭对水中镉(Ⅱ)的吸附性能及去除机理

以酶解木质素液化产物树脂(LP树脂)为前驱体,借助微波加热和直接混合法,成功制得了镁改性泡沫炭(Mg/CF)吸附材料,通过红外光谱、X射线衍射、X射线光电子能谱等对其结构性能进行了分析表征,并借助静态吸附实验对其水中Cd(Ⅱ)的脱除性能进行了考察。结果表明,负载于CF表面的镁以MgO纳米颗粒的形式集中分布于CF的泡孔孔壁上,MgO的负载并未减少CF的比表面积,但可使其微孔孔容增大。该吸附材料对水中Cd(Ⅱ)表现出优越的脱除性能,与单独使用MgO相比,Mg/CF对Cd(Ⅱ)的理论最大吸附容量可达 308.51 mg·g^-1,约为 MgO 的 2.0倍,且平衡吸附时间为 720 min,较 MgO 明显缩短。Mg/CF 对 Cd(Ⅱ)的去除过程满足准二级动力学方程、Langmuir吸附等温线模型,且去除过程为吸热熵增的自发过程。去除机理研究表明,Mg/CF对Cd(Ⅱ)的去除是以离子交换和沉淀等化学作用为主,并伴有物理吸附的过程。     

镁改性泡沫炭对水中镉(Ⅱ)的吸附性能及去除机理

以酶解木质素液化产物树脂(LP树脂)为前驱体,借助微波加热和直接混合法,成功制得了镁改性泡沫炭(Mg/CF)吸附材料,通过红外光谱、X射线衍射、X射线光电子能谱等对其结构性能进行了分析表征,并借助静态吸附实验对其水中Cd(Ⅱ)的脱除性能进行了考察。结果表明,负载于CF表面的镁以MgO纳米颗粒的形式集中分布于CF的泡孔孔壁上,MgO的负载并未减少CF的比表面积,但可使其微孔孔容增大。该吸附材料对水中Cd(Ⅱ)表现出优越的脱除性能,与单独使用MgO相比,Mg/CF对Cd(Ⅱ)的理论最大吸附容量可达 308.51 mg·g^-1,约为 MgO 的 2.0倍,且平衡吸附时间为 720 min,较 MgO 明显缩短。Mg/CF 对 Cd(Ⅱ)的去除过程满足准二级动力学方程、Langmuir吸附等温线模型,且去除过程为吸热熵增的自发过程。去除机理研究表明,Mg/CF对Cd(Ⅱ)的去除是以离子交换和沉淀等化学作用为主,并伴有物理吸附的过程。     

荞麦皮生物吸附去除水中Cr(Ⅵ)的吸附特性和机理

农业废弃物荞麦皮作为生物吸附剂去除水中Cr(Ⅵ),研究了荞麦皮对Cr(Ⅵ)的去除动力学以及溶液pH、吸附剂用量和Cr(Ⅵ)初始浓度对去除效率的影响;通过FT-IR,XPS,SEM-EDX对荞麦皮表面组成和结构进行表征,探索荞麦皮去除Cr(Ⅵ)的机理.结果显示:荞麦皮对Cr(Ⅵ)有很高的去除效率.常温下5.0 g·L-1的荞麦皮在pH=2.0下对100 mg·L-1 Cr(Ⅵ)溶液的去除率可达99.87%.荞麦皮对Cr(Ⅵ)的去除率随溶液pH降低而升高,在pH=2.0时达到最大;随吸附剂用量增加而增大;随Cr(Ⅵ)初始浓度增加而减小.单位质量荞麦皮对Cr(Ⅵ)的去除量随吸附剂用量增加而减小;随Cr(Ⅵ)初始浓度增加而增加,最后趋于稳定.在20℃,pH=2.0,吸附用量为5.0 g·L-1时,荞麦皮对Cr(Ⅵ)的最大去除容量约为36.4 mg·g-1.荞麦皮吸附去除Cr(Ⅵ)的过程符合准二级吸附动力学.FT-IR,XPS和SEM-EDX分析结果表明:荞麦皮是一个多孔材料,表面存在羧基、氨基、羟基等活性基团;荞麦皮对Cr(Ⅵ)的去除是一个吸附-还原耦合的过程,包括Cr(Ⅵ)在荞麦皮表面上的静电吸附,以及此后的固相还原和对还原态的Cr(Ⅲ)再吸附;Cr(Ⅲ)的吸附主要是通过与荞麦皮表面的羧基、氨基的配位,以及与其中的阳离子发生离子交换作用实现的.     

PEI功能化秸秆生物炭对水中Cr 6+的吸附性能

选取玉米秸秆为原料, 经过缺氧炭化制备玉米秸秆生物炭, 并以聚乙烯亚胺(PEI)负载于生物炭表面, 制备PEI功能化秸秆生物炭, 研究了其对水中Cr ⁶⁺的吸附性能和机理. 结果表明, 在吸附剂添加量相等条件下, PEI碱性生物炭(PBC)对Cr ⁶⁺的吸附效率明显高于PEI酸性生物炭(HBC)和原始生物炭(CBC). PBC对水中Cr ⁶⁺的最大吸附量为386.3 mg/g, 吸附平衡时间为300 min; 当pH=2.0左右时, 对Cr ⁶⁺的吸附效率最大达到95.94%. 因此, PBC可作为一种高效去除水中Cr ⁶⁺的吸附剂.     

Removal of radiocobalt from aqueous solution by oxidized MWCNT

The study was undertaken to evaluate the feasibility of oxidized multiwalled carbon nanotube (oxidized MWCNT) for the removal of radiocobalt (⁶⁰Co) from aqueous solutions. The oxygen functional groups of oxidized MWCNT were characterized by FT-IR and XPS. Batch experiments were performed to study the sorption of cobalt as a function of contact time, solid contents, pH, ionic strength, foreign ions, and temperature. Two kinetic models viz. pseudo-first-order and pseudo-second-order were used to determine kinetic sorption parameters, and the kinetic sorption could be described more favorably by the pseudo-second-order model. The thermodynamic parameters (∆G°, ∆S°, ∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on oxidized MWCNT was an endothermic and spontaneous processes. The results suggest that oxidized MWCNT can be used efficiently in the treatment of industrial effluents containing radioactive and heavy metal ions.     

Removal of methyl violet from aqueous solution by perlite

The use of perlite for the removal of methyl violet from aqueous solutions at different concentration, pH, and temperature has been investigated. Adsorption equilibrium is reached within 1 h. The capacity of perlite samples for the adsorption of methyl violet was found to increase with increasing pH and temperature and decrease with expansion and increasing acid-activation. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. The adsorption isotherm was measured experimentally at different conditions and the experimental data were correlated reasonably well by the adsorption isotherm of Langmuir. The order of heat of adsorption corresponds to a physical reaction. It is concluded that the methyl violet is physically adsorbed onto the perlite. The removal efficiency (P) and dimensionless separation factor (R) have shown that perlite can be used for removal of methyl violet from aqueous solutions, but unexpanded perlite is more effective.     

Dye and its removal from aqueous solution by adsorption: A review

In this review article the authors presented up to-date development on the application of adsorption in the removal of dyes from aqueous solution. This review article provides extensive literature information about dyes, its classification and toxicity, various treatment methods, and dye adsorption characteristics by various adsorbents. One of the objectives of this review article is to organise the scattered available information on various aspects on a wide range of potentially effective adsorbents in the removal of dyes. Therefore, an extensive list of various adsorbents such as natural materials, waste materials from industry, agricultural by-products, and biomass based activated carbon in the removal of various dyes has been compiled here. Dye bearing waste treatment by adsorption using low cost alternative adsorbent is a demanding area as it has double benefits i.e. water treatment and waste management. Further, activated carbon from biomass has the advantage of offering an effected low cost replacement for non-renewable coal based granular activated carbon provided that they have similar or better adsorption on efficiency. The effectiveness of various adsorbents under different physico-chemical process parameters and their comparative adsorption capacity towards dye adsorption has also been presented. This review paper also includes the affective adsorption factors of dye such as solution pH, initial dye concentration, adsorbent dosage, and temperature. The applicability of various adsorption kinetic models and isotherm models for dye removal by wide range of adsorbents is also reported here. Conclusions have been drawn from the literature reviewed and few suggestions for future research are proposed.     

Adsorption and removal of tetracycline antibiotics from aqueous solution by graphene oxide

Significant concerns have been raised over pollution of antibiotics including tetracyclines in aquatic environments in recent years. Graphene oxide (GO) is a potential effective absorbent for tetracycline antibiotics and can be used to remove them from aqueous solution. Tetracycline strongly deposited on the GO surface via π-π interaction and cation-π bonding. The adsorption isotherm fits Langmuir and Temkin models well, and the theoretical maximum of adsorption capacity calculated by Langmuir model is 313 mg g(-1), which is approximately in a close agreement with the measured data. The kinetics of adsorption fits pseudo-second-order model perfectly, and it has a better rate constant of sorption (k), 0.065 g mg(-1) h(-1), than other adsorbents. The adsorption capacities of tetracycline on GO decreased with the increase in pH or Na(+) concentration. The adsorption isotherms of oxytetracycline and doxycycline on GO were discussed and compared.     

Removal of methylene blue from aqueous solution by graphene oxide

Graphene oxide (GO) is a highly effective absorbent of methylene blue (MB) and can be used to remove MB from aqueous solution. A huge absorption capacity of 714 mg/g is observed. At initial MB concentrations lower than 250 mg/L, the removal efficiency is higher than 99% and the solution can be decolorized to nearly colorless. The removal process is fast and more efficient at lower temperatures and higher pH values. The increase of ionic strength and the presence of dissolved organic matter would further enhance the removal process when MB concentration is high. The results indicate that GO can be applied in treating industrial effluent and contaminated natural water. The implications to graphene-based environmental technologies are discussed.     

Removal of phosphate from aqueous solution by zeolite synthesized from fly ash

Fifteen Chinese fly ashes were converted hydrothermally into zeolites, and phosphate immobilization capacity (PIC) of the synthesized zeolites and the corresponding raw fly ashes were determined using an initial phosphate concentration of 1000 mg/L. Results showed that there was a remarkable increase in PIC (from 1.2 to 7.6 times) following the synthesis process. Fractionation of immobilized phosphorus indicated that Fe+Al-P increased most significantly and consistently among all the phosphorus fractions following the conversion of fly ash to zeolite. The PIC and Ca+Mg-P were closely related to Ca content (with r values of 0.9683 and 0.9651, respectively) rather than Mg content (with r values of 0.3920 and 0.3212, respectively). The r values of PIC and Fe+Al-P with Fe content (with r values of 0.4686 and 0.6385, respectively) were higher than those with Al content (with r values of -0.7857 and -0.3770, respectively). Although calcium and iron components were mainly involved in phosphate immobilization, there was no significant change of Ca and Fe content following the conversion of fly ash to zeolite. Increase in dissociated Fe(2)O(3) and specific surface area probably accounted for the enhancement in PIC of synthesized zeolites compared with corresponding fly ashes. The PIC value of zeolites showed a significant correlation with dissociated Fe(2)O(3) (r=0.6186). The specific surface area increased 26.0-89.4 times as a result of the conversion of fly ash to zeolite. The maximum removal of phosphate occurred within different pH ranges for zeolites which were synthesized from high, medium and low calcium fly ashes and this behavior was explained by the reaction of phosphate with calcium and iron components.     

Removal of 2,4-dichlorophenol from aqueous solution by static-air-activated carbon fibers

Static-air-activated carbon fibers (ACFs) with lotus-root-like axially porous structure were used to adsorb 2,4-dichlorophenol (2,4-DCP) from aqueous solution. The adsorption isotherm was evaluated in the pH range 3.0-11.0. Results indicated that both Langmuir and Redlich-Peterson adsorption isotherms were appropriate for describing the adsorption characteristics of 2,4-DCP at various pH values and that lower pH values were favorable for adsorption. The adsorption of 2,4-DCP was controlled by the synergetic effects of pi-pi interaction and electrostatic attraction, and the former was dominant. Breakthrough curve results showed that the 2,4-DCP removal efficiency increased with an increase in the empty-bed contact time (EBCT). An EBCT of 0.660 min was sufficient for the adsorption of 2,4-DCP onto ACF, indicating a high adsorption rate. Desorption experiment results revealed that the ACF saturated with 2,4-DCP could be regenerated effectively by a 0.001 M NaOH solution.     

Removal of radiocobalt from aqueous solution by different sized carbon nanotubes

Batch adsorption technique was applied to study the adsorption of radiocobalt on multiwalled carbon nanotubes (CNTs) with deferent sizes. The aim of this work was to examine the effect of contact time, pH, solid content, foreign ions and CNT particle sizes on the removal of Co(II) ions from aqueous solutions by CNTs. The results indicated that the adsorption of Co(II) was strongly dependent on pH and the adsorption capacity was in inverse proportion to the particle sizes of CNTs. The adsorption of Co(II) was weakly affected by ionic strength and foreign ions. Ion exchange and surface complexation were the main adsorption mechanisms. The kinetics of Co(II) adsorption on CNTs was described well by pseudo-second-order model. The Langmuir and Freundlich models were applied to interpret the adsorption data. The results are important to understand the physicochemical behavior of Co(II) with CNTs, and for the application of CNTs in the preconcentration of radiocobalt from large volumes of aqueous solutions.     

Removal and recovery of uranium from aqueous solution by tea waste

Experiments on the removal and recovery of U(VI) from aqueous solution by tea waste were conducted. The adsorbent was characterized by scanning electron microscope and energy dispersive spectrometer before and after the adsorption treatment. The removal of U(VI) amounts to 86.80?% at optimum pH 6. The adsorption process reaches its equilibrium in 12?h at 308?K, and the kinetic characteristic can be described by the pseudo-second-order kinetic equation. The amount of adsorption increases from 22.92 to 142.21?mg?g^?1 with the decrease of tea waste dosage from 100 to 10?mg for solution with an initial uranium concentration of 50?mg?L^?1. Desorption for the four strippants is higher than 80?%. The equilibrium data are more agreeable with Freundlich isotherm than Langmuir isotherm.     

溶剂气浮法分离水中的Zn离子的研究

以双硫腙为配体,溴化十六烷基三甲基铵（CTAB）为表面活性剂。对Zn离子在无机相中形成的Zn-双硫腙-CTAB体系的溶剂气浮进行了研究。研究表明表面活性剂与Zn离子的物质的量之比为5：1,约1h水中的锌离子去除率可达98％。0．5mol／L NaCl大大提高体系的溶剂气浮的去除率,溶剂气浮的速率随着气流速率的增加而增加,共存溶质乙醇存在会使去除率降低,有机溶剂的量对溶剂气浮影响较小,溶剂气浮过程遵从假一级动力学。考察了不同温度下溶剂气浮的回收速率,计算了该过程中的气浮表观活化能为9．037kJ／mol。