改性香蕉叶对Ca~(2+)的吸附性能研究

以改性香蕉叶作为吸附材料吸附溶液中的Ca~(2+),研究了Na OH浓度和反应时间对香蕉叶改性效果的影响,并研究了吸附时间、温度、吸附剂用量、Ca~(2+)初始质量浓度、溶液p H值对改性香蕉叶吸附性能的影响,包括吸附平衡和吸附动力学过程。结果发现,改性香蕉叶吸附剂的最佳制备方案为:Na OH浓度为0.2mol/L,反应时间为1h;改性香蕉叶吸附剂对Ca~(2+)的吸附平衡较好地符合Langmuir吸附等温式,其吸附动力学符合准二级动力学模型,由此确定其吸附类型为化学吸附;通过红外光谱分析和扫描电镜显示,改性的过程可除去香蕉叶纤维表面的果胶、半纤维素、木质素,使Ca~(2+)更容易接触纤维表面而被吸附。     

氨基硫脲改性纤维素的合成及其对Hg(Ⅱ)的吸附

通过氯化和胺解两步反应,对玉米秸秆纤维素骨架中的羟基进行化学改性,得到氨基硫脲改性的纤维素。通过红外光谱和电子能谱对该改性玉米秸秆纤维素进行了表征,并研究了作为吸附剂对水溶液中Hg(Ⅱ)的吸附能力。结果表明:所获得的氨基硫脲改性纤维素对Hg(Ⅱ)的最大饱和吸附量为499.6mg/g;吸附模型符合Langmuir吸附等温模型和准二级动力学模型,拟合系数R2在0.98以上;改性纤维素材料表面富有的氨基硫脲官能团与重金属Hg(Ⅱ)离子发生的表面络合作用,增加了其吸附性能。     

改性小麦秸杆纤维素球对苯酚吸附性能研究

本文利用制得的改性小麦秸秆纤维素球对苯酚吸附性能进行了研究。实验结果表明:改性小麦秸秆纤维素球对苯酚的吸附30min内基本达到平衡,吸附剂对苯酚吸附量随起始质量浓度的增加而增加,且呈线性关系;在T=298K、pH=5.0时,吸附剂对苯酚的吸附量达到最大。在一定浓度、温度条件下,改性小麦秸秆纤维素球吸附苯酚的过程符合Freundlich吸附模型。吸附再生实验表明,改性小麦秸秆纤维素球对苯酚有较好的吸附再生能力。并对印染废水中的苯酚进行了实际的吸附测定。     

改性纤维素的制备及分光光度法对Cu~(2+)吸附研究

针对日益严重的铜离子污染问题,以化学浆纤维素为原料,通过氨基酸接枝修饰2,2,6,6-四甲基哌啶氧自由基(TEMPO)氧化体系氧化的纤维素,制备出一种新型吸附剂,并采用灵敏简便的分光光度法研究改性对铜离子的吸附效果。结果表明,氨基酸修饰纤维素(AMC)与TEMPO氧化纤维素(TOC)相比,对铜离子的吸附效果有不同程度的提升,其中组氨酸改性的吸附效果最好,低浓度时吸附率可以高达97%。随着浓度增大,吸附率下降,但是吸附量增大,当吸附200 mg/L的Cu2+溶液时,吸附量可达47 mg/g。此外,研究了不同条件下AMC对Cu2+的吸附情况,包括AMC投加量、初始浓度、pH值等。结果表明,吸附过程的吸附模型符合Langmuir等温模型,吸附动力学可以用准二级吸附动力学方程拟合。     

甘蔗渣纤维素的改性及应用进展

甘蔗渣纤维素是一种环保的绿色高分子材料、具有可再生性,对其进行高效改性应用范围越来越广泛。文章介绍了甘蔗渣纤维素的结构和性质,综述了化学改性甘蔗渣纤维素的研究进展,包括甘蔗渣纤维素醚类反应、酯类反应、接枝共聚物以及其均相改性方法。概述了改性甘蔗渣纤维素作为吸附剂、复合材料及其他功能材料研究应用现状,并展望了改性甘蔗渣的发展前景。     

多乙烯多胺改性纤维素及其对水中砷、氟、铬吸附性能研究

以木浆为原材料,采用高碘酸钠氧化法制备了醛基纤维素,并在温和的条件下以多乙烯多胺改性制备了氨基改性纤维素吸附剂.探究了氨基改性纤维素吸附剂对水中有害离子F-、Cr2O72-和AsO43-的吸附性能,结果发现该吸附剂对F-、Cr2O72-和AsO43-离子具有高的吸附能力,并可实现较快速的吸附平衡.其吸附过程受到pH值的影响,随着pH升高,对Cr2O72-和AsO43-的吸附能力增加,当pH接近中性时,F-离子吸附能力下降.在竞争离子的存在下,对Cr2O72-和AsO43-仍具有极强的选择吸附性,推测其吸附为络合吸附机理,而对F-则主要为静电力吸附机理,吸附选择性较差.     

吡啶酮改性纤维素吸附剂对金属离子的吸附性能

经过两步简单反应合成了一种新型吡啶酮功能化纤维素吸附剂。该吸附剂的结构和表面形貌分别通过红外光谱和扫描电镜进行了表征,研究了其作为吸附剂对重金属离子的吸附性能。结果表明,吡啶酮双酸改性后纤维素吸附剂的表面变粗糙、比表面积增大,该吸附剂对Cu~(2+)、Pb~(2+)、Cd~(2+)、Co~(2+)的最大吸附容量分别达到146.52mg/g、233.05mg/g、192.08mg/g、258.13mg/g;对金属离子的吸附行为符合拟二阶动力学模型和Langmuir等温吸附模型;通过对吸附剂吸附金属离子前后的红外光谱研究,发现吡啶酮的酮羰基和羧酸基团同时参与了金属离子的吸附过程。     

卟啉钒在改性高岭土上的吸附行为及机理研究

利用酸改性和负载钼的酸改性高岭土作为吸附剂研究了环己烷中的卟啉钒(钒氧-2,3,7,8,12,13,17,18-八乙基卟啉,VO-OEP)在这两种吸附剂上的吸附行为,从热力学角度探讨了吸附机理。结果表明,两种吸附剂对卟啉钒的吸附符合Langmuir吸附等温线,卟啉钒单层吸附在改性高岭土上;吸附表现为自发热过程,吸附热均大于40 kJ/mol,说明吸附形成了化学键。     

微波辅助细菌纤维素酯的制备及对Pb(Ⅱ)的高效去除

以细菌纤维素(BC)为原料,通过微波辅助酯化改性的方法制得了两种改性细菌纤维素,细菌纤维素黄原酸酯(XMBC)和细菌纤维素硫酸酯(SMBC)。对所制备的样品进行X射线衍射(XRD)、扫描电镜-电子能谱(SEM-EDS)、傅里叶变换红外(FT-IR)光谱和BET比表面积分析,通过续批式实验考察其对Pb(Ⅱ)的去除效果。研究了pH值、反应时间、温度、污染物初始浓度、离子强度对其吸附能力的影响以及材料再生性能。结果表明,改性细菌纤维素的比表面积和孔容均有上升,其对Pb(Ⅱ)的吸附量随反应温度和离子强度的增加而降低,最优pH值为5.0。巯基的引入增强了细菌纤维素对Pb(Ⅱ)的吸附能力,改性后的吸附剂显示出比原始BC更优异的吸附性能,其中XMBC和SMBC的最大吸附量分别为144.93和126.58 mg·g^-1,该吸附过程符合准二级速率方程和Langmuir等温吸附模型。材料对Pb(Ⅱ)的吸附是自发的放热过程,且吸附剂易于再生和重复回收。因此, SMBC和XMBC作为从水中富集分离重金属的新型材料具有及大应用前景。     

磷酸化油菜秸秆纤维素吸附剂的制备及对溶菌酶的吸附

以天然产物油菜秸秆纤维素粉作为基质,二甲基甲酰胺为交联剂,磷酸为修饰剂,制备了新型磷酸化油菜秸秆纤维素生物吸附剂。用红外光谱、透射电子显微镜及X射线光电子能谱,对油菜秸秆纤维素和磷酸化油菜秸秆纤维素吸附剂进行表征。研究了油菜秸秆纤维素粉改性前后对溶菌酶的吸附,包括吸附溶液的pH值、溶菌酶的初始浓度、吸附时间、温度及NaCl的浓度等因素对吸附的影响。结果表明,在温度25℃,pH值7.4,吸附时间10h的条件下,磷酸化油菜秸秆纤维素粉微球对溶菌酶的吸附容量为451.71 mg·g-1,而未修饰油菜秸秆纤维素粉微球对溶菌酶的吸附容量只有332.43mg·g-1。在优化条件下用修饰吸附剂从鸡蛋清中分离纯化溶菌酶,纯化倍数为19.8,收得率为51.3%。     

Characteristic and mechanism of Cr(Ⅵ) adsorption by ammonium sulfamate-bacterial cellulose in aqueous solutions

A new adsorbent, ammonium sulfamate-bacterial cellulose (ASBC), was prepared through chemical modifications of bacterial cellulose. The process of adsorbing Cr(Ⅵ) including its isotherm and kinetics, was measured and studied. The results showed that pH value was a very important parameter to the adsorbing efficiency. The adsorption kinetics can be described by a pseudo-second rate model and a particle diffusion equation. Both physical and chemical adsorptions existed in the adsorption process, but chemical adsorption was more dominatant. And particles internal diffusion was not the only rate controlling step. The adsorption equilibrium can be described by the Langmuir type, which indicated that a typical single-molecule layer adsorption of Cr(Ⅵ) by ASBC could be described. And the rate of adsorption followed the Slips model well, which indicated that ASBC had some multiphase and asymmetry. The coordination adsorption and ion exchange effect were the main mechanisms of chemical adsorption. The absorbed Cr(Ⅵ) can be desorbed effectively by 0.5 mol/L EDTA or HCl from the adsorbent, which could make it be reusable.     

载铁(Ⅲ)-配位体交换棉纤维素吸附剂对饮用水中砷(Ⅴ)和氟联合去除的研究

使用新型载铁(Ⅲ)-配位体交换棉纤维素吸附剂,通过静态和动态吸附实验,研究了饮用水中砷酸钠[砷(Ⅴ)]和氟化钠(氟)联合去除的效果和浓度因素的影响以及吸附剂经过反复吸附-洗脱再生-再吸附后性能的稳定性.结果表明,该吸附剂能够高效、高选择性地联合去除高砷(Ⅴ)和高氟.吸附柱的饱和吸附容量可高达15mg/g干重,反复使用中饱和体积的相对标准偏差小于0.5%,柱处理出水的各项有关指标均符合我国生活饮用水卫生标准,特别是砷(Ⅴ)的质量浓度低于0.010mg/L,符合世界健康组织(WHO)推荐的饮用水严格砷标准.说明该吸附剂在砷氟共存的地区具有很好的应用前景.     

Review on recent advances of carbon based adsorbent for methylene blue removal from waste water

The growth in textile and printing industries proven detrimental to the aquatic environment as the industrial waste containing dye seeped into the ecosystem. A high concentration of dye in water possess negative impacts on water ecosystem and harmful to human health. Removal of methylene blue (MB) dye from industrial waste via adsorption pathway has been widely investigated that promised high efficiency of MB removal. This review will summarize researches published from 2008 to 2019 on the removal of MB using carbon adsorbent with focus will be given on the synthesis and modification of carbon-based materials, and the structural properties influencing the performance of MB adsorption. Summary on the type of material used for the synthesis of carbon materials (activated carbon and biochar) will be included from utilization of the naturally occurring carbon sources such as polymers, biomasses and biowastes, and also sucrose and hydrocarbon gases. Modification of carbon materials such as chemical activation and physical activation; surface grafting to form functionalized surfaces; deposition with metal and magnetic nanoparticles via impregnation; and manufacturing of carbon composites will be discussed on the effects to promote MB adsorption and desorption. Another type of carbon adsorbents such as porous carbon; graphitic carbons including graphite, graphene, graphene oxide, and carbon nitride (g-C₃N₄); and finally nanocarbon in the form of nanotube, nanorod and nanofiber; will be included in the review with details on the synthesis method and the correlation between structural properties and adsorption activity. The regeneration process to increase the life cycle of carbon adsorbent will also be discussed based on two regeneration pathway i.e. a thermal degradation and desorption on MB. Finally the thermodynamics, kinetics, and the adsorption models of MB on carbon adsorbent will be discussed in this review.     

Plasma Treated Sepiolite: A New Adsorbent for Removal of Malachite Green from Contaminated Water

Surface modification of clay materials has become an important issue to improve the efficiency of the adsorbent. The adsorption capacity of the clay material can be increased by thermal or chemical modifications. In this study, plasma technology was applied for the surface modification of sepiolite to improve the removal of malachite green from contaminated water. This study is novel in preparing and examining the effectiveness of sepiolite in adsorption of malachite green from contaminated water. To achieve the aim, plasma application time, CO₂, N₂, or Ar plasma gases effect and pH were investigated with respect to the adsorption capacity of MG. The surface properties of raw and plasma treated sepiolite were investigated with SEM, FTIR, BET surface area and XRD measurements. The monolayer adsorption capacity was found to be 143 mg/g.     

Facial Synthesis of Adsorbent from Hemicelluloses for Cr(VI) Adsorption

It is challenging work to develop a low-cost, efficient, and environmentally friendly Cr(VI) adsorbent for waste water treatment. In this paper, we used hemicelluloses from chemical fiber factory waste as the raw material, and prepared two kinds of carbon materials by the green hydrothermal method as adsorbent for Cr(VI). The results showed that hemicelluloses hydrothermally treated with citric acid (HTC) presented spherical shapes, and hemicelluloses hydrothermally treated with ammonia solution (HTC-NH₂) provided spongy structures. The adsorption capacity of the samples can be obtained by the Langmuir model, and the adsorption kinetics could be described by the pseudo-second-order model at pH 1.0. The maximum adsorption capacity of HTC-NH₂ in the Langmuir model is 74.60 mg/g, much higher than that of HTC (61.25 mg/g). The green hydrothermal treatment of biomass with ammonia solution will provide a simple and feasible way to prepare adsorbent for Cr(VI) in waste water treatment.     

A POSS‐Phosphazene Based Porous Material for Adsorption of Metal Ions from Water

The development of adsorptive materials continues to be an important area of research for removal of heavy metal ions from waste water. The adsorption capacity can be modulated by both physical and chemical modification of the adsorbent. Herein, we combine the unique properties of polyhedral oligomeric silsesquioxane (POSS) and organocyclophosphazene as the building units to synthesize a hybrid porous material, abbreviated as PN‐POSS. The synthetic method follows a Heck reaction between hexa(4‐bromophenoxy)cyclotriphosphazene and octavinylsilsesquioxane (OVS). The Brunauer–Emmett–Teller (BET) analysis shows that the material possesses micro‐ and mesopores of 1.5 and 3.8 nm size and a surface area on the order of 500 m² g^?1. These attributes in combination with the donor ability of the phosphazene units qualify the material for high adsorption of Pb²⁺, Hg²⁺ and Cu²⁺ ions with maximal adsorption capacities on the order of 1326, 1927 and 2654 mg g^?1, respectively. The adsorbent exhibits a good regeneration performance and can be effectively used for water treatment.     

Preparation and characterization of a novel adsorbent for removing lipophilic organic from water

The initial twelve persistent organic pollutants (POPs) in Stockholm Convention on Persistent Or-ganic Pollutions include many organochlorinated pes-ticides (OCPs) and some industrial by-products from manufacture processes, most of which are lipophilic or…     

Effective removal of anionic dyes from aqueous solutions by novel polyethylenimine-ozone oxidized hydrochar (PEI-OzHC) adsorbent

The adsorption behavior of the anionic dyes Remazol Brilliant Blue R (RBBR) and Reactive Black 5 (RB5) from aqueous solutions by polyethylenimine ozone oxidized hydrochar (PEI-OzHC) was investigated. The adsorption capacities of both dyes increased with functionalization of PEI in the hydrochar adsorbent. The results of surface characterization (FTIR, BET, TGA, elemental analysis, and SEM) showed that PEI modification greatly enhanced the adsorbent surface chemistry with a slight improvement of adsorbent textural properties. In addition, the adsorption kinetics data showed an excellent adsorption efficiency as reflected in the high removal percentages of the anionic dyes. The Isotherm results indicated that RBBR and RB5 dye adsorption occurred via monolayer adsorption, and chemisorption was the rate-controlling step. The PEI-OzHC adsorbent possesses higher maximum Langmuir adsorption capacity towards RBBR (218.3 mg/g) than RB5 (182.7 mg/g). This increase in adsorption capacity is attributed to the higher number of functional groups in RBBR that interact with the adsorbent. This study reveals the potential use of adsorbents derived from pine wood hydrochar in municipal as well as industrial wastewater treatment. Furthermore, surface chemistry modification is proven as an effective strategy to enhance the performance of biomass-derived adsorbents.     

Adsorption of carboxymethyl cellulose on polymer surfaces: evidence of a specific interaction with cellulose

The adsorption of carboxymethyl cellulose (CMC), one of the most important cellulose derivatives, is crucial for many scientific investigations and industrial applications. Especially for surface modifications and functionalization of materials, the polymer is of interest. The adsorption properties of CMC are dependent not only on the solutions state, which can be influenced by the pH, temperature, and electrolyte concentration, but also on the chemical composition of the adsorbents. We therefore performed basic investigation studies on the interaction of CMC with a variety of polymer films. Thin films of cellulose, cellulose acetate, deacetylated cellulose acetate, polyethylene terephthalate, and cyclo olefin polymer were therefore prepared on sensors of a QCM-D (quartz crystal microbalance) and on silicon substrates. The films were characterized with respect to the thickness, wettability, and chemical composition. Subsequently, the interaction and deposition of CMC in a range of pH values without additional electrolyte were measured with the QCM-D method. A comparison of the QCM-D results showed that CMC is favorably deposited on pure cellulose films and deacetylated cellulose acetate at low pH values. Other hydrophilic surfaces such as silicon dioxide or polyvinyl alcohol coated surfaces did not adsorb CMC to a significant extent. Atomic force microcopy confirmed that the morphology of the adsorbed CMC layers differed depending on the substrate. On hydrophobic polymer films, CMC was deposited in the form of larger particles in lower amounts whereas hydrophilic cellulose substrates were to a high extent uniformly covered by adsorbed CMC. The chemical similarity of the CMC backbone seems to favor the irreversible adsorption of CMC when the molecule is almost uncharged at low pH values. A selectivity of the cellulose CMC interaction can therefore be assumed. All CMC treated polymer films exhibited an increased hydrophilicity, which confirmed their modification with the functional molecule.     

A Simple One-Step Modification of Shrimp Shell for the Efficient Adsorption and Desorption of Copper Ions

Removing toxic heavy metal species from aqueous solutions is a point of concern in our society. In this paper, a promising biomass adsorbent, the modified waste shrimp shell (MS), for Cu (II) removal was successfully prepared using a facile and simple one-step modification, making it possible to achieve high-efficiency recycling of the waste NaOH solution as the modification agent. The outcome shows that with the continuous increase in pH, temperature and ion concentration, the adsorption effect of MS on Cu (II) can also be continuously improved. Adsorption isotherm and adsorption kinetics were fitted with the Langmuir isotherm model and the pseudo-second-order model, respectively, and the maximum adsorption capacity of Cu (II) as obtained from the Langmuir isotherm model fitting reached 1.04 mmol/g. The systematic desorption results indicated that the desorption rate of Cu (II) in the MS could reach 100% within 6 min, where HNO₃ is used as the desorption agent. Moreover, experiments have proven that after five successive recycles of NaOH as a modifier, the adsorption capacity of MS on Cu (II) was efficient and stable, maintaining tendency in 0.83–0.85 mmol/g, which shows that waste NaOH solution can be used as a modification agent in the preparation of waste shrimp shell adsorbent, such as waste NaOH solution produced in industrial production, thereby making it possible to turn waste into renewable resources and providing a new way to recycle resources.