壳聚糖/木质素磺酸钠吸附剂的制备及其除Pb2+和Cd2+

工业废水给水体和土壤带来巨大的灾害,严重影响农作物的生长.为了获得洁净水,须制备一种稳定、有效、可持续的处理剂来控制水污染.使用木质素磺酸钠和壳聚糖,以自由基聚合法在聚丙烯酸上制备木质素基水凝胶吸附剂,并将其应用于除去Pd2+和Cd2+.采用正交法对木质素磺酸钠、壳聚糖、交联剂以及引发剂的含量进行优化.分别利用傅里叶红外光谱仪、扫描电镜图、热分析仪以及Zeta电位仪对吸附剂进行表征.探究不同条件对木质素基水凝胶吸附Pb2+和Cd2+的影响,在此基础上建立动力学和等温线模型.结果表明:在吸附剂为0.015 g、重金属离子浓度为100 mg·L-1、pH值为7时,对Pd2+的吸附容量为367 mg·g-1,对Cd2+的吸附容量为296 mg·g-1.同时,揭示木质素基水凝胶剂的吸附过程是一种以静电吸附为辅、化学吸附为主的吸附模式.     

多氨基改性蔗渣对水溶液中Pb~(2+)、Zn~(2+)、Cd~(2+)、Cu~(2+)吸附性能的研究

蔗渣经多氨基改性处理后,得到多氨基改性蔗渣吸附剂。考察了多氨基改性蔗渣吸附剂对模拟废水中Pb2+、Zn2+、Cd2+、Cu2+的吸附性能,主要包括吸附时间、溶液pH值和温度对吸附量的影响以及吸附等温式的研究。研究表明,在实验范围内,Pb2+的吸附平衡时间为12h,适宜吸附Pb2+的pH值范围在4～5,Pb2+的最大吸附量为34.96mg/g;Zn2+的吸附平衡时间为20h,适宜吸附Zn2+的pH值在6.2左右,Zn2+的最大吸附容量为2.24mg/g;Cd2+的吸附平衡时间为20h,适宜吸附Cd2+的pH值在5.0左右,Cd2+的最大吸附容量为10.40mg/g;Cu2+的吸附平衡时间为20h;适宜吸附Cu2+的pH值在5.0左右;Cu2+在不同温度下的最大吸附容量为2.60mg/g。多氨基改性蔗渣对Pb2+、Zn2+、Cd2+、Cu2+的吸附均可用Freundlich方程和Langmuir方程描述。     

香草醛改性壳聚糖对镉离子的吸附热力学和动力学

研究了微波辐射条件下香草醛改性壳聚糖(V-CTS)对Cd2+离子的吸附性能,测定了吸附等温线和吸附动力学曲线。结果表明,该吸附剂对Cd2+离子的吸附行为符合Freundlich吸附等温式,在298～318K温度范围内,焓变ΔH=24.22kJ/mol,表明吸附是吸热过程。吸附动力学符合Lagergren二级吸附速率方程,反应活化能为25.58kJ/moL,表明V-CTS对金属离子的吸附由化学反应控制,而非扩散控制。吸附剂解吸再生循环使用4次后,镉离子的吸附容量仅减少18.9%,该吸附剂具有较好地再生使用性。     

HKUST-1/KCoFC复合材料的制备及其对Cs+的吸附研究

在这项工作中,制备了一种以金属有机配位聚合物(MOFs)材料(HKUST-1)为载体,通过KCoFC(Co(NO₃)₂与K₄Fe(CN)₆反应产物)功能化修饰后的新型复合材料,并通过FTIR、SEM、XRD对其进行表征。研究初始Cs⁺浓度、吸附时间、溶液pH值对吸附效果的影响,用吸附动力学和吸附等温线模型研究HKUST-1/KCoFC对Cs⁺的吸附过程。实验表明:在40 min内,Cs⁺吸附量迅速增加,复合材料对Cs⁺吸附量最佳的pH为8;HKUST-1/KCoFC对Cs⁺吸附过程符合准二级动力学和Langmuir模型。     

玉米须吸附剂去除水溶液中Pb2+的研究

利用废弃物玉米须制备生物质吸附剂,研究其对废水中重金属Pb2+的吸附效果。考察体系pH值、Pb2+初始浓度、吸附剂添加量以及共存离子K+、Na+、Ca2+、Mg2+对吸附率的影响。结果表明:在25℃,玉米须吸附Pb2+的最佳pH值为4.0;吸附剂添加量为0.150g,金属初始浓度为40mg/L时,吸附率高达99%以上。其动力学数据符合准二级动力学模型,Langmuir-Freundlich模型成功拟合了平衡数据,由该模型所得吸附剂的最大吸附容量为68.533mg/g。利用Zeta电位仪、红外光谱仪和扫描电镜进一步探讨玉米须对重金属的吸附机理。结果表明:玉米须外表面遍布墙形褶皱,断面存在孔道,这有利于对Pb2+的吸附;当体系pH>2.0时,玉米须颗粒表面带负电,可以和Pb2+发生静电吸附;-COOH、-OH、-C=O等含氧官能团参与了吸附过程。     

玉米须吸附剂去除水溶液中Pb2+的研究

利用废弃物玉米须制备生物质吸附剂,研究其对废水中重金属Pb2+的吸附效果。考察体系pH值、Pb2+初始浓度、吸附剂添加量以及共存离子K+、Na+、Ca2+、Mg2+对吸附率的影响。结果表明:在25℃,玉米须吸附Pb2+的最佳pH值为4.0;吸附剂添加量为0.150g,金属初始浓度为40mg/L时,吸附率高达99%以上。其动力学数据符合准二级动力学模型,Langmuir-Freundlich模型成功拟合了平衡数据,由该模型所得吸附剂的最大吸附容量为68.533mg/g。利用Zeta电位仪、红外光谱仪和扫描电镜进一步探讨玉米须对重金属的吸附机理。结果表明:玉米须外表面遍布墙形褶皱,断面存在孔道,这有利于对Pb2+的吸附;当体系pH>2.0时,玉米须颗粒表面带负电,可以和Pb2+发生静电吸附;-COOH、-OH、-C=O等含氧官能团参与了吸附过程。     

功能化SBA-15介孔材料的制备及其吸附性能研究

硅基介孔材料因其特有的特性,被用于去除废水中重金属离子的吸附剂.为了提高对目标污染物的吸附容量, 本文采用一步法和两步法制备了氨基或巯基功能化SBA-15介孔材料,利用傅里叶红外光谱仪、场发射扫描电镜、X射线衍射仪和氮气吸附脱附表征测试了材料的化学组成、微观形貌和物相结构.测试结果显示经功能化处理后的样品成功地接枝氨基或巯基功能基团.研究发现,经功能化处理后,材料的骨架结构及介孔孔道均未被破坏,但有序性下降且出现少许团聚,物性参数也有一定程度下降,功能化材料对Zn²⁺、Pb²⁺、Cr³⁺和Cu²⁺的吸附率均有大幅度提高.经氨基或巯基功能化后,SBA-15介孔材料对水体中重金属离子的吸附率有很大提高,但一步法制备的功能化硅基介孔材料因模板剂去除不彻底而影响了对重金属离子的吸附效率,两步法制备的功能化硅基介孔材料对重金属离子的吸附效果更好,说明本文的功能化硅基介孔材料工艺是可行有效的,但两步法合成的功能化介孔材料具有更好的吸附效果.     

污泥灰对Cd(Ⅱ)和Ni(Ⅱ)的吸附作用研究

在静态条件下,以改性城市污泥为吸附剂,研究了污泥灰(MSSA)对重金属离子的吸附性能,着重探讨了改性污泥灰去除工业电镀废水中重金属离子Cd(Ⅱ)、Ni(Ⅱ)的适宜条件.结果表明,pH值是影响污泥灰对重金属离子吸附的重要因素,镉(Ⅱ)、镍(Ⅱ)吸附的最佳pH值为6.0和6.5;当吸附剂最佳用量为10g/L时,Cd(Ⅲ)、Ni(Ⅱ)的吸附容量分别达到1.21mg/g和1.02mg/g;吸附等温线可以用Freundilich和Langmuir模型描述,吸附过程基本符合Langmuir和Freundilich吸附等温式.该吸附剂吸附性能优越,可有效地去除废水中的相关金属离子.     

木质纤维素基纳米复合材料对Pb~(2+)、Cd~(2+)的吸附研究

以原位插层共聚法制备木质纤维素-g-丙烯酸/丙烯酰胺/蒙脱土(LNC-g-AA/AM/MMT)纳米复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)对其结构进行表征。研究在金属离子初始浓度、吸附时间、吸附温度、pH值等不同吸附条件下,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+吸附性能的影响。结果表明,当Pb2+、Cd2+初始浓度分别为0.04和0.06mol/L,吸附时间分别为120和60min,吸附温度分别为40和30℃,pH值为5.5时,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+的吸附量分别高达504.2和246.9 mg/g。整个吸附过程均符合Langmuir吸附等温线模型和伪二级动力学模型,且是个自发放热的反应过程。同时对最佳条件下吸附饱和的LNC-g-AA/AM/MMT纳米复合材料进行解吸研究,脱附率分别为93.4%和92.9%。     

聚乙烯亚胺-羧甲基纤维素的合成及对金属离子的吸附性能

以羧甲基纤维素(CMC)为基质,用戊二醛(GA)做交联剂,将聚乙烯亚胺(PEI)交联到羧甲基纤维素上制得聚乙烯亚胺-羧甲基纤维素吸附剂(PEI-CMC)。采用傅里叶变换红外光谱、扫描电镜、X射线光电子能谱对PEI-CMC的结构进行了表征,测定了其对Cu2+、Pb2+和Cd2+的吸附性能,并研究了pH值、时间、金属离子的初始浓度对吸附的影响。结果表明,当CMC、PEI和GA的反应比为1 g∶5 mL∶20 mL,反应温度为25℃,反应时间为3 h时,合成的PEI-CMC的含氮量为13.23%。当CMC和PEI的反应比为1 g∶5 mL时,随着戊二醛(质量分数2.5%)的加入量增加,PEI-CMC的产率先增大后降低。在pH值1~14的范围内,溶液酸碱度的变化对PEI-CMC的交联度没有影响。PEI-CMC吸附剂对Cu2+、Pb2+和Cd2+的吸附量在实验范围内随pH升高而增加。PEI-CMC对Pb2+和Cu2+、Cd2+的吸附在90 min和180 min后分别达到平衡,吸附动力学符合准二级反应动力学模型。随着Cu2+、Pb2+和Cd2+初始浓度的增加,PEI-CMC对Cu2+、Pb2+和Cd2+的吸附量开始时快速增加,而后达到饱和,吸附等温数据符合Freundlich模型,最大吸附容量分别为Cu2+250.0mg/g、Pb2+635.9 mg/g、Cd2+142.8 mg/g。     

The preparation of low-cost adsorbent for heavy metal based on furfural residue

In this research, with furfural residue as the raw material and phenolic resin as the adhesive, low-cost adsorbent based on furfural residue was made, and characterized with scanning electron microscopy (SEM), nitrogen adsorption–desorption analysis, and Fourier transform infrared spectrophotometry (FTIR). The adsorbent was used to adsorb Cd²⁺, Ni²⁺, Pb²⁺, Cu²⁺ and Zn²⁺ in the water, and the experimental conditions of adsorption and elution were researched. In addition, the thermodynamics and dynamics mechanism of the adsorption were also investigated. The results demonstrate the lignin, cellulose and hemicellulose in furfural residue were bonded and solidified, and a new adsorbent based on furfural residue was obtained. In the medium of pH 5–7, the resin presented powerful adsorbing capacity toward heavy metal in water, and the adsorption capacities of the material for Cd²⁺, Pb²⁺, Zn²⁺, Cu²⁺ and Ni²⁺ were found to be 18.3, 98.2, 34.8, 45.1 and 14.7?mg/g, respectively. The adsorptive behavior was proved to be consistent with the Freundlich adsorption isotherm model and the second-order rate equation. The adsorption was driven by entropy, and it was an endothermic and spontaneously physical process. After the application of adsorbent, 1?mol/L nitric acid could be used for regeneration. The adsorbent has been applied to the treatment of wastewater and the results are satisfactory.     

Waste calcite sludge as an adsorbent for the removal of cadmium, copper, lead, and zinc from aqueous solutions

Sludge residues, an industrial waste material for the removal of cadmium (Cd²⁺), copper (Cu²⁺), lead (Pb²⁺), and zinc (Zn²⁺) from aqueous solutions were investigated using batch method. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, initial concentration, and contact time. The results indicated that the adsorbent showed good sorption potential and maximum metal removal was observed at pH ≥?3. Within 120?min of operation, about 63.7, 95.2, 99.9, and 88.2% of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions were removed from the solutions, respectively. Sorption curves were well fitted to the Langmuir and Freundlich models. The adsorption capacities for Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions at optimum conditions were 121.2, 1067.8, 566.4, and 534.2?mg?g^?1, respectively. The kinetics of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ adsorption from aqueous solutions was analyzed by fitting the experimental data to pseudo-first- and pseudo-second-order kinetic models. However, the pseudo-first-order kinetics model provided much better R ² values and the rate constant was found to be 0.001?min^?1 for Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions. The results revealed that sludge residues can adsorb considerable amount of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions and it could be an economical method for the removal of these ions from aqueous systems.     

Nanoscale zero-valent iron modified with carboxymethyl cellulose in an impinging stream-rotating packed bed for the removal of lead(II)

A novel impinging stream-rotating packed bed (IS-RPB) was proposed to continuous, macro and industrialized prepare nanoscale zero-valent iron (nZVI) with simultaneously modified with carboxymethyl cellulose (CMC) for the removal of Pb²⁺. The obtained CMC-nZVI particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The components on the surface of CMC-nZVI after react with Pb²⁺ were also analyzed by X-ray photoelectron spectroscopy (XPS). The IS-RPB makes it possible for the continuous, macro and industrialized preparing of CMC-nZVI particles, and CMC can significantly improve the dispersion and reduce aggregation of nZVI particles. The effects of solution pH, initial Pb²⁺ concentration and reaction time on the removal efficiency of Pb²⁺ by nZVI and CMC-nZVI particles were also investigated. The results show that CMC-nZVI particles outperform nZVI particles in removing Pb²⁺, and the removal efficacy reaches a maximum of 838.84 mg·g⁻¹ for nZVI particles and 1237.32 mg·g⁻¹ for CMC-nZVI particles at pH = 6.0. The adsorption of Pb²⁺ by nZVI and CMC-nZVI particles can be described by the Langmuir isotherm adsorption model with a R² of 0.999, and the calculated maximum adsorption capacity is 900.90 and 1376.07 mg·g⁻¹ for nZVI and CMC-nZVI particles. The adsorption of Pb²⁺ follows the pseudo second-order kinetics with a linear correlation coefficient R² of 0.999. In addition, the effect of co-existing cations such as Na⁺, Cu²⁺, Ni²⁺ and Cd²⁺ on Pb²⁺ removal efficiency was also investigated. The results showed that Na⁺ had no effect on Pb²⁺ removal efficiency and Cu²⁺ and Ni²⁺ had inhibited Pb²⁺ removal efficiency. Cd²⁺ had an inhibitory effect on Pb²⁺ removal efficiency when the concentration was 50 mg·L⁻¹ and 100 mg·L⁻¹, Cd²⁺ enhanced Pb²⁺ removal efficiency while the concentration of Cd²⁺ was 200 mg·L⁻¹.     

The study of adsorption characteristics Cu and Pb ions onto PHEMA and P(MMA-HEMA) surfaces from aqueous single solution

The adsorption characteristics of Cu²⁺ and Pb²⁺ ions onto poly2-hydroxyethyl methacrylate (PHEMA) and copolymer 2-hydroxyethyl methacrylate with monomer methyl methacrylate P(MMA-HEMA) adsorbent surfaces from aqueous single solution were investigated with respect to the changes in the pH of solution, adsorbent composition (changes in the weight percentage of MMA copolymerized with HEMA monomer), contact time and the temperature in the individual aqueous solutions. The linear correlation coefficients of Langmuir and Freundlich isotherms were obtained. The results revealed that the Langmuir isotherm fitted the experimental results better than the Freundlich isotherm. Using the Langmuir model equation, the monolayer adsorption capacity of PHEMA surface was found to be 0.840 and 3.037 mg/g for Cu²⁺ and Pb²⁺ ions and adsorption capacity of (PMMA-HEMA) was found to be 31.153 and 31.447 mg/g for Cu²⁺ and Pb²⁺ ions, respectively. Changes in the standard Gibbs free energy (ΔG⁰), standard enthalpy (ΔH⁰) and standard entropy (ΔS⁰) show that the adsorption of mentioned ions onto PHEMA and P(MMA-HEMA) are spontaneous and exothermic at 293–323 K.     

Efficient removal of heavy metal ions from aqueous solution using salicylic acid type chelate adsorbent

In this study, 5-aminosalicylic acid was successfully grafted onto the poly(glycidyl methacrylate) (PGMA) macromolecular chains of PGMA/SiO₂ to obtain a novel adsorbent designated as ASA-PGMA/SiO₂. The adsorption properties of ASA-PGMA/SiO₂ for heavy metal ions were studied through batch and column methods. The experimental results showed that ASA-PGMA/SiO₂ possesses strong chelating adsorption ability for heavy metal ions, and its adsorption capacity for Cu²⁺, Cd²⁺, Zn²⁺, and Pb²⁺ reaches 0.42, 0.40, 0.35, and 0.31 mmol g⁻¹, respectively. In addition, pH has a great influence on the adsorption capacity in the studied pH range. The adsorption isotherm data greatly obey the Langmuir and Freundlich model. The desorption of metal ions from ASA-PGMA/SiO₂ is effective using 0.1 mol l⁻¹ of hydrochloric acid solution as eluent. Consecutive adsorption-desorption experiments showed that ASA-PGMA/SiO₂ could be reused almost without any loss in the adsorption capacity.     

Comparative and competitive adsorption of cadmium, copper, nickel, and lead ions by Iranian natural zeolite

The competitive adsorption behavior of cadmium (Cd²⁺), copper (Cu²⁺), nickel (Ni²⁺), and lead (Pb²⁺) ions using Iranian natural zeolite has been studied in order to determine its applicability in treating industrial wastewater. Tests to determine both the rate of adsorption and the uptake at equilibrium were performed under batch conditions from single- and multi-component solutions. The optimum conditions for the treatment process were investigated by observing the influence of pH levels, the presence of competing ions, varying the mass of zeolite and different contact time. Adsorption kinetics of the zeolite followed first-order kinetics, showing about 100 % of Pb²⁺ removal within 40 min and reaching an equilibrium state within 24 h for Cd²⁺, Cu²⁺, and Ni²⁺. The results indicated that removal of metals from single- and multi-component solutions is best described by a Freundlich isotherm, in which the distribution coefficient was in the following order: Pb²⁺ > Cu²⁺ > Cd²⁺ > Ni²⁺. In the multi-component solutions, metals exhibit competitive adsorption on the zeolite. The adsorption is reduced to 90, 53, 30, and 22 % of single component of Cu²⁺, Ni²⁺, Cd²⁺, and Pb²⁺, respectively. However, the total adsorption was higher than single component. Finally, soil solution saturation indices and speciation of metals was assessed using Visual MINTEQ 2.6 software, and probability of precipitation of minerals supported by scanning electron microscopy. The research indicates that Cd²⁺ and Ni²⁺ retention by zeolite can be viewed as the result of ion exchange reaction, but Pb²⁺ and Cu²⁺ retention is both due to ion exchange and precipitation. These results show that Iranian natural zeolite particularly effective in removing cationic heavy metal species from industrial wastewater.     

Highly selective ion-imprinted particles for solid-phase extraction of Pb ions

The Pb²⁺-imprinted (PHEMAC-Pb²⁺) particles were prepared by bulk polymerization as a solid-phase extraction (SPE) adsorbent. N-methacryloyl-(l)-cysteine (MAC) was used as functional monomer to have a well-shaped molecular geometry between MAC monomer and Pb²⁺ ions that provide molecular recognition based on well fitted cavities for Pb²⁺ ions after removal of template ions. The PHEMAC-Pb²⁺ particles were characterized and the applicability of these particles was investigated for the solid-phase extraction of Pb²⁺ ions from aqueous solutions and environmental samples. The PHEMAC-Pb²⁺ particles with a size range of 50–200 µm have a rough surface and macropores in bulk structure. The adsorption capacity of the PHEMAC-Pb²⁺ particles is relatively low (2.01 mg/g). However, the high selectivity towards competitive ions (Cd²⁺, Ni²⁺ and Cu²⁺) promises the PHEMAC-Pb²⁺ particles an alternative SPE adsorbent in literature. The relative selectivity coefficients of PHEMAC-Pb²⁺ particles for Pb²⁺/Ni²⁺, Pb²⁺/Cd²⁺ and Pb²⁺/Cu²⁺ were almost 71, 117 and 192 times greater than that of non-imprinted (PHEMAC) particles, respectively. Moreover, the reusability of the PHEMAC-Pb²⁺ particles was tested for several times and no significant loss in adsorption capacity was observed. The accuracy of the proposed procedure was also verified by the determination of Pb²⁺ ions in the certified reference material, LGC 6137 Estuarine sediment.     

Novel negatively charged hybrids. 3. Removal of Pb2+ from aqueous solution using zwitterionic hybrid polymers as adsorbent

Using zwitterionic hybrid polymers as adsorbent, the adsorption kinetics and isotherm, thermodynamic parameters of ΔG, ΔH and ΔS for the removal of Pb²⁺ from aqueous solution were investigated. It is indicated that the adsorption of Pb²⁺ ions on these zwitterionic hybrid polymers followed the Lagergren second-order kinetic model and Freundlich isotherm model, demonstrating that the adsorption process might be Langmuir monolayer adsorption. The negative values of ΔG and the positive values of ΔH evidence that Pb²⁺ adsorption on these zwitterionic hybrid polymers is spontaneous and endothermic process in nature. Moreover, the zwitterionic hybrid polymers produced reveal relatively higher desorption efficiency in 2 mol dm^?3 aqueous HNO₃ solution, indicating that they can be recycled in industrial processes. These findings suggest that these zwitterionic hybrid polymers are the promising adsorbents for Pb²⁺ removal and can be potentially applied in the separation and recovery of Pb²⁺ ions from the waste chemicals and contaminated water of lead-acid rechargeable battery.     

Synthesis and characterization of poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) copolymer beads for removal of lead ions

N-methacryloyl-(l)-glutamic acid (MAGA) was synthesized using methacryloyl chloride and l-glutamic acid methyl ester as a metal-complexing ligand and/or comonomer. MAGA was characterized by FTIR and NMR. Spherical beads with an average diameter of 150–200 μm were obtained by suspension polymerization of MAGA and 2-hydroxyethyl methacrylate (HEMA) performed in an aqueous dispersion medium. Poly(HEMA-MAGA) beads were characterized by swelling studies, surface area measurements and elemental analysis. Poly(HEMA-MAGA) beads have a specific surface area of 56.7 m²/g. Poly(HEMA-MAGA) beads were used in the removal studies of Pb²⁺ ions. Adsorption equilibrium was achieved in about 60 min. The adsorption of Pb²⁺ ions onto PHEMA beads was negligible (0.38 mg/g). The MAGA incorporation into the polymer structure significantly increased the lead adsorption capacity (348 mg/g). The adsorption of Pb²⁺ ions increased with increasing pH and reached a plateau value at around pH 5.0. Competitive adsorption of heavy metal ions from synthetic wastewater was also studied. The adsorption capacities are 42.5 mg/g for Pb²⁺, 26.8 mg/g for Hg²⁺ and 17.6 mg/g for Cd²⁺ at 0.5 mmol/l metal concentration. Consecutive adsorption and elution operations showed the feasibility of repeated use for poly(HEMA-MAGA) chelating beads.     

Potential Malaysia agricultural waste materials for the biosorption of cadmium(II) from aqueous solution

Biosorption of cadmium(II) ions (Cd²⁺) onto Ananas comosus (AC) peel, Parkia speciosa (PS) pods and Psidium guajava (PG) peel were investigated in this study. Batch sorption experiments were performed by investigating the effect of initial pH. It was found that Cd²⁺ uptake was highly dependent on the initial pH and Cd²⁺ removal efficiency was highest for PG peel, followed by AC peel and PS pods. Biosorption experiments were carried out using different initial Cd²⁺ concentration and the experimental data obtained was fitted to both Langmuir and Freundlich isotherms. The experimental data was found to best fit the Langmuir isotherm, and adsorption capacities of 18.21 mg/g (AC peel), 25.64 mg/g (PS pods) and 39.68 mg/g (PG peel) were obtained. Comparison with published adsorption capacities for other low-cost biosorbents indicates that PS pods and PG peel have potential as low-cost biosorbent materials for the removal of Cd²⁺ from aqueous solution.