Preparation and Characterisation of Corncob-Based Biosorbents in Côte d’Ivoire

This study focuses on the preparation of corncob-based biosorbents. The chemical impregnation method was used to vary the chemical agent namely phosphoric acid H3PO4 (BA) and sodium hydroxide NaOH (BB). The physicochemical analysis of the two biosorbents indicated that under the same preparation conditions, the bio-sorbents have after activation yields lower than 50% (24.37% for BB and 49.09% for BA). In addition, the biosorbents have iodine index values between 444.17 mg/g and 418.79 mg/g and specific surfaces related to the adsorption of methylene blue ranging from 18.54 m2/g to 19.70 m2/g. The study of surface functional groups by using the Boehm test and pH zero point charge (pHPZC) confirmed the acidic nature of BA and BB biosorbents with respective values pHPZC = 4.01 and pHPZC = 4.90. The Langmuir method and BET analysis determined the specific surface areas by liquid phase adsorption of methylene blue as well as the porosity. The BET surface areas of BA and BB obtained are 72.01 m2/g and 63.10 m2/g respectively. The influence of the chemical activating agent on the formation of pores was confirmed by electron microscopy (SEM) analysis. From this study, it is found that the best activating agent for corn cobs was found to be phosphoric acid because the BA biosorbent was revealed to be the most favourable due to its surface area and good pore volume which are high compared to sodium hydroxide NaOH. Moreover, their application as adsorbent for effluent treatment could be explored.

Optimized Adsorption of Small and Medium Molecules by a Biosorbent Based on Hevea Hulls

In the context of the recovery of agricultural waste, many researches have focused on the preparation of adsorbents from natural waste from fruit trees, egg shells, palm waste or sawdust. This work aims to optimize the preparation of a biosorbent from rubber hulls by studying its ability to adsorb small and medium molecules. The influence of parameters such as drying temperature (X1), particle size (X2), stirring time (X3) and sodium hypochloride mass (X4) was studied. The results indicate that the model used for biosorbent optimization on methylene blue and iodine index is significant. In addition, this model has greater adsorption capabilities on small molecules than with large molecules. Statistical analysis of the data shows that temperature is the most influential factor in the adsorption of small molecules. On the other hand, particle size has a significant influence on the adsorption of large molecules. The optimum biosorbent preparation values are 1.0 for drying temperature (X1), −1.0 for biosorbent grain size (X2), 1.0 for stirring time (X3) and 1.0 for sodium hypochloride mass (X4).

Influence of Temperature on Equilibrium, Kinetic and Thermodynamic Parameters of Biosorption of Cr(VI) onto Fish Scales as Suitable Biosorbent

In this work the potential of fish scales as a suitable biosorbent for removal of Cr(VI) ions from aqueous solutions was investigated at various temperatures. The influence of temperature on equilibrium, kinetics as well as thermodynamic parameters was investigated. Various isotherm models such as Langmuir, Freundlich, R - P, D - R, Temkin and Halsey were used for the mathematical description of the biosorption of Cr(VI) ions onto fish scales. It was observed that Freundlich model exhibited the best fit to experimental data. Amongst the various kinetic models tested, the pseudo-first-order kinetic model represented the best correlation for the biosorption of Cr(VI) onto fish scales at various temperatures. In addition, various thermodynamic parameters such as ?Go, ?Ho and ?So were also determined. The biosorption of Cr(VI) was found to be a spontaneous and endothermic process.

Assessment of Sericin Biosorbent for Selective Dye Removal

The silk sericin is the main residue in silk production and it is found to be a low cost and efficient bio-sorbent. In this study, sericin was characterized with various techniques including SEM （scanning electron micro- scope）, XRD, N2 physisorption, FTIR （Fourier transformed infrared spectroscopy） and XPS （X-ray photoelectron spectroscopy）. The nitrogen content of sericin was ca. 8.5 mmol.g-1 according to elemental analysis. Dye adsorption by sericin biosorbent was investigated with the acid yellow （AY）, methylene blue （MB） and copper （II） phthalocyanine-3,4＇4＂4＇＂-tetrasulfonic acid （CuPc） dyes from water. Sericin displayed large capacity for AY andCuPc adsorption with adsorption capacities of respectively 3.1 and 0.35 mmol.g-1, but it did not adsorbed methyl- ene blue dye. This selectivity is due to the basicity of amide groups in seriein biosorbents.

Removal of Heavy Metal Ions from Wastewater by Using Biosorbents from Marine Algae-A Cost Effective New Technology

Heavy metal pollution from industrial wastewater is a worldwide environmental issue. Biosorption of heavy metals by using biosorbents derived from various types of biomass has been shown to be effective for the uptake of heavy metal ions. In this study, biosorbents derived from the biomass of a group of marine macroalgae were used for the removal and recovery of heavy metal ions from aqueous solutions. Results indicated that the biosorbents have high uptake capacities and affinities for a number of heavy metal ions. The uptake capacities of the biosorbents were in the range of 1.0 to 1.5mmol·g-1 for divalent heavy metal ions. The kinetics of the uptake process was fast and the process can be used in both batch and fixed-bed operations. It appears that the biosorption process by using biosorbents from marine macroalgae can be an efficient and cost effective technology for the treatment of heavy metal containing wastewater.

Understanding association between methylene blue dye and biosorbent: Palmyrah sprout casing in adsorption process in aqueous phase

Water pollution caused by industrial dyes has become a severe problem in the modern world. Biosorbents can be used in an eco-friendly manner to remove industrial dyes. In this study, five biosorbents were selected: palmyrah sprout casing (PSC), manioc peel, lime peel, king coconut husk, and coconut kernel. Batch adsorption experiments were conducted to identify the best biosorbent with the highest ability to adsorb methylene blue (MB) from wastewater. The detailed mechanisms of PSC used in the adsorptive removal of MB in aqueous phase were investigated. Of the five biosorbents, PSC exhibited the best removal performance with an adsorption capacity at equilibrium (qe) of 27.67 mg/g. The qe values of lime peel, king coconut husk, manioc peel, and coconut kernel were 24.25 mg/g, 15.29 mg/g, 10.84 mg/g, and 7.06 mg/g, respectively. To explain the mechanisms of MB adsorption with the selected biosorbents, the Fourier transform infrared (FTIR) spectrometry and X-ray diffraction (XRD) analyses were performed to characterize functional properties, and isotherm, kinetic, rate-limiting, and thermodynamic analyses were conducted. The FTIR analysis revealed that different biosorbents had different functional properties on their adsorptive surfaces. The FTIR and XRD results obtained before and after MB adsorption with PSC indicated that the surface functional groups of carbonyl and hydroxyl actively participated in the removal process. According to the isotherm analysis, monolayer adsorption was observed with the Langmuir model with a determination coefficient of 0.998. The duration to reach the maximum adsorption capacity for MB adsorption with PSC was 120 min, and the adsorption process was exothermic due to the negative enthalpy change (-9.950 kJ/mol). Moreover, the boundary layer thickness and intraparticle diffusion were the rate-limiting factors in the adsorption process. As a new biosorbent for MB adsorption, PSC could be used in activated carbon production to enhance the performance of dye removal.

Production and Characterization of Green Biosorbent Based on Modified Corn Cob Decorated Magnetite Nanoparticles

In most developing countries, particularly in the countries of sub-Saharan Africa, corn cobs are considered as waste polluting the environment during the harvest period of this cereal. In order to valorize this agricultural waste, high-performance, inexpensive and low-energy consumption magnetic bioadsorbents were prepared from corn cobs. The chemically activated raw corn cob was magnetized by coating the surface with magnetite nanoparticles. The prepared biosorbents were characterized by FT-IR, XRD, FE-SEM associated with EDX, HR-TEM, TG analysis, BET surface area analysis and XPS. The maximum specific surface area of 35.22 m2/g was reached. An attempt to use of these magnetic biosorbents for the removal of heavy metal like Cr(VI) from aqueous solution was envisaged.

Valorization of Mango Peels as Low-Cost Biosorbent in Methylene Blue Adsorption:Kinetic and Equilibrium Study

Mango peels,which constitute a significant proportion of urban waste,have been modified with phosphoric acid for use as a biosorbent in the removal of methylene blue from wastewater.The characterization of the obtained biosorbent showed that cellulose is the primary constituent followed by lignin and hemicellulose.The high water content and the low value of ash content indicate that the studied biosorbent is a porous material containing a low proportion of inorganic,inert,amorphous and unusable part for biosorbent production.The zero charge point(pHpzc)assessment showed that the overall surface charge of the biosorbent is negative and therefore plays a key role in the adsorption process.The adsorption of methylene blue by mango peels biosorbent is a two-step process:a rapid first step in which over 90%methylene blue is removed in less than 10 min followed by a slowdown of the adsorption rate when approaching the adsorption equilibrium.Among pseudo-first,pseudo-second order and intraparticle diffusion kinetics models studies,pseudo-second order was the best applicable to describe methylene blue adsorption,suggesting a two-step mechanism:the transfer of methylene blue molecules from the solution to the mango peels biosorbent surface,followed by the interaction between adsorbates and surface.The equilibrium adsorption data were analyzed by Langmuir,Freundlich and Temkin isotherms models.Among them,Langmuir was the best model to describe adsorption,indicating the existence of homogeneous distribution of adsorption sites on mango peels biosorbent surface and a mono-layer adsorption of methylene blue molecules.The low value of Temkin’s constant B relative to the interaction energy between methylene blue molecules and the surface of the biosorbent shows that the adsorption involved is a physisorption process.

生物吸附剂改性栗蓬的制备及其对Cr(Ⅵ)吸附性能的研究

以农林废弃物栗蓬为原料,过氧化氢为改性剂,制备了对Cr(Ⅵ)具有良好吸附性能的生物吸附材料。以吸附率为优化目标,在单因素实验的基础上进行正交试验得到最佳改性条件为温度80℃、过氧化氢浓度10.0%、盐酸浓度0.01 mol·L^(-1)、时间0.5 h。采用傅立叶红外光谱(FT-IR)及扫描电镜(SEM)对改性栗蓬结构进行了表征。通过正交试验优化改性栗蓬对Cr(Ⅵ)的吸附条件,在改性栗蓬投加量0.8 g、Cr(Ⅵ)初始浓度20 mg·L^(-1)、吸附时间60 min条件下,对Cr(Ⅵ)的吸附率为61.8%。通过动力学方程拟合得到改性栗蓬对Cr(Ⅵ)的吸附过程符合准二级动力学方程。热力学实验表明,改性栗蓬对Cr(Ⅵ)的吸附为放热、熵减小的过程。

生物吸附剂Bio-matrix去除废水中重金属的研究

[目的]研究生物吸附剂Bio-matrix对常规重金属Cu^(2+)、Ni^(2+)、Cr^(3+)的吸附性能。[方法]考察不同温度、吸附剂投加量、吸附时间、p H对吸附量的影响,并分析了Bio-matrix对Cu^(2+)的等温吸附情况。[结果]Bio-matrix吸附剂对Cu^(2+)的吸附效果优于Ni^(2+)和Cr^(3+),温度对吸附量影响较小,3 h可达到吸附平衡,单位吸附量随p H的升高先增大后减小,在p H 4左右时对重金属的单位吸附量最大,Bio-matrix对Cu^(2+)的吸附等温线与Freundlich方程有较好的拟合性,饱和吸附量为19.3 mg/g。[结论]该研究为Bio-matrix作为生物吸附剂去除废水中重金属提供了可行途径。

再生角蛋白凝胶对纺织退浆废水中浆料分子的吸附性能

为实现废弃角蛋白纤维资源的高值化循环利用,在采用“还原预处理-甲酸”溶解法获取角蛋白多肽并引入α-硫辛酸进行化学改性基础上,制备再生凝胶材料用于纺织退浆废水中浆料分子的吸附处理。借助扫描电子显微镜、傅里叶红外光谱等测试技术对角蛋白凝胶的结构和性能进行表征。针对聚乙烯醇(PVA)和淀粉2种浆料,探究凝胶对不同浆料分子的吸附规律及机制。结果表明:角蛋白凝胶具有均匀的三维孔隙结构,其化学组成和官能团结构与原纤维基本一致,且结晶程度较高;该凝胶对溶液体系中PVA分子的吸附量和去除率分别为16.278 mg/g和30.013%,对淀粉浆料则可达到133.234 mg/g和28.868%;此外,吸附动力学和热力学研究显示,角蛋白凝胶对2种浆料的吸附规律均符合准二级动力学模型,其中对PVA分子主要为物理吸附作用,而对淀粉则可能存在化学吸附效果。

化学修饰生物吸附剂处理重金属废水的研究进展

工业的快速发展产生了大量的重金属废水,由于重金属具有不可降解性,导致其在环境中不断累积,对人类和环境健康造成严重影响。在众多处理重金属废水的方法中,生物吸附法因具有反应条件温和、可同时处理多种重金属离子的优点而被广泛应用。但单一生物吸附剂往往无法满足对目标金属离子的高效去除,因此需要对其进行化学修饰以获得更高效的生物吸附剂。分析了重金属废水的特性,归纳总结了化学修饰生物吸附剂的方法,综述了经化学修饰后生物吸附剂处理重金属废水的研究现状,为化学修饰生物材料的进一步发展提供参考。

基于数学模型对胞外聚合物吸附Cu^(2+)、Cd^(2+)的研究

文章利用三维模型构建出吸附曲面对活性污泥中胞外聚合物(EPS)对Cu^(2+)、Cd^(2+)吸附行为进行研究预测,并讨论离子竞争吸附机理。在单一金属体系中EPS对Cu^(2+)(534.72 mg/g)的吸附量要高于Cd^(2+)(504.71 mg/g)。通过三维模型模拟出三维吸附曲面可以看出Cu^(2+)的存在明显抑制了EPS对Cd^(2+)的吸附,但Cd^(2+)对Cu^(2+)的吸附干扰很小,EPS与Cu^(2+)的亲和力要高于Cd^(2+),其吸附过程更适用于Langmuir等温线,吸附质与吸附位点一一对应。结合红外光谱、三维荧光光谱和SEM-EDX分析表明,EPS在吸附前后材料形貌发生了明显变化,该现象出现的原因可能是金属离子的吸附是通过羧基、羟基、酰胺等活性官能团与金属离子成键及络合作用;同时离子交换也是EPS吸附金属离子的一个重要机制。该研究为进一步发掘利用胞外聚合物及后续应用提供理论依据和技术支持。

柚皮吸附材料制备工艺的设计优化探索

通过对干燥、活化和改性过程的参数调控,成功提升了柚皮吸附剂的吸附效率和选择性。优化后的吸附剂在处理低浓度重金属离子时表现出优异性能,且具有良好的可再生性和稳定性。

生物吸附剂的制备及其对铬的吸附性能

通过对吸附时间、吸附液pH值、溶液含铬浓度与菌丝球投加量的效应值与极值进行正交分析 ,确定出影响生物吸附效果的各因素依次是 :吸附时间→吸附液pH值→菌丝球投加量→铬浓度 .实验筛选出了两个对铬具有良好吸附性能的菌种 :黄曲霉 (Aspergillusflavus)、曲霉属 (Aspergillussp .) .在吸附 8h的条件下 ,它们对含铬 1 5mg·l- 1的吸附液除铬率分别达 6 7 1 %和 71 2 % ,两者的最佳吸附条件是 :pH =5 ,铬菌投加比为 5mg·g- 1.以这两种霉菌为主 ,通过吸附性能实验 ,探讨了多种因素对生物吸附剂除铬性能的影响 .

高效生物吸附剂处理含铬废水

将菌株(R32)和复合菌群(Fh01)2种生物吸附剂与活性污泥进行复合使用,观察了柱式生物曝气法对高浓度含铬模拟水样和含铬电镀废水的生物吸附效果.结果表明,这2种吸附剂性能稳定,对进水pH值适应范围广,当pH值为1.0~7.0时,R32对50.0mg/L铬的去除率达71%~86%;当pH值为1.0~5.0时,Fh01对铬的去除率均在60%以上.R32对铬浓度、进水速度、处理时间等因素均具有较好的适应性.而Fh01对低浓度含铬废水的处理效率高,当总Cr浓度为5.0~20.0mg/L时,对铬的去除率达100%.R32和Fh01串联曝气处理效果理想,吸附2h后,对总Cr, Cu2+, CODCr浓度分别为78.3,2.29,45.0mg/L的电镀废水的去除率分别高达94.0%,99.2%,74.5%.

改性柿子生物吸附剂对铜和铅的吸附性能

以柿子粉为原料,分别采用硫酸和硝酸进行化学改性制备两种柿子生物吸附剂SPP和HPP,研究它们对Cu2+和Pb2+的吸附性能,考察溶液pH值、固液比、温度、吸附时间以及金属离子浓度及对吸附性能的影响。结果表明:SPP和HPP的吸附过程可以很好地用准二级动力学方程描述,吸附等温线用Langmuir方程拟合的效果优于Freundlich方程的;SPP对Cu2+和Pb2+的最大吸附容量分别为61.47 mg/g和207.90 mg/g,HPP对Cu2+和Pb2+的最大吸附容量分别为64.0 mg/g和220.8 mg/g,吸附过程为化学吸附所控制。

重金属的生物吸附研究进展

对重金属污水的生物吸附研究进行了综述 ,主要介绍了生物吸附剂的来源、种类 ;预处理、固定化及脱附的方法与试剂。详细介绍了影响重金属生物吸附去除的各种因素 ,并探讨了生物积累和吸附机理。

生物吸附剂ZL5-2对Cr(Ⅵ)的吸附机理

研究了Agrobacterium sp．产生的生物吸附剂ZL5．2对Or（Ⅵ）的吸附作用，并对吸附Or（Ⅵ）前后及解吸附后的ZL52进行了红外光谱分析．结果表明，ZL5．2对Or（Ⅵ）吸附的最佳pH为0．5～1．5，随着pH增大，吸附作用减弱，ZL5-2吸附Cr（Ⅵ）可在短时间内完成。10min时即有65．4％的Or（Ⅵ）被吸附，60min时吸附率达到90％以上，80min后所有的Or（Ⅵ）都被吸附．该吸附过程符合Langmuir和Freundlich等温吸附方程，被吸附的Or（Ⅵ）可以被解吸附，解吸率为13．6％～67．9％．通过红外光谱分析，推测该吸附过程属于物理吸附，存在可逆吸附和不可逆吸附，以可逆吸附为主．

酵母菌-活性污泥法吸附处理含铬电镀废水的性能

研究了解脂假丝酵母 (Candidalipolytica 1977)、产朊假丝酵母 (Candidautilis 12 2 5 )和活性污泥处理含铬电镀废水的吸附与还原性能 结果表明 ,解脂假丝酵母对废水的 pH适应范围广 .当 pH =3 2～ 6 0时 ,2 5g/L菌体对电镀废水中 30 2mg/L总铬的去除率达 85 0 % ;对 2 7 7mg/LCr6+ 的还原率高达 10 0 % .2株酵母协同处理电镀废水 ,可以有效的提高铬的生物吸附效率 ,对 30 2mg/L总铬的去除率达 91 1% .曝气生物吸附法研究结果表明 ,该法是本研究中处理含铬电镀废水最有效的方法 .10 g/L酵母菌 ,5 g/L活性污泥处理 5 0 3mg/L总铬、4 6 2mg/LCr6+ 水样 8h后 ,去除率达 93 8% ;而当污泥浓度为 10 g/L时 ,去除率高达 99 5 % .