A New Metal-Chelated Cryogel for Reversible Immobilization of Urease

Poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) [poly(HEMA-GMA)] cryogel was synthesized by cryopolymerization technique at frozen temperature. Iminodiacetic acid (IDA) was then attached covalently to the cryogel as a chelating agent. Then, poly(HEMA-GMA)-IDA cryogel was chelated with Ni(II) ions and this novel metal affinity support was used for adsorption of urease from its aqueous solution. Urease adsorption experiments were carried out in a continuous system by using a peristaltic pump. Maximum urease adsorption onto poly(HEMA-GMA)-IDA-Ni(II) cryogel was found to be 11.30 mg/g cryogel at pH 5.0 acetate buffer and in 25 °C medium temperature. Urease adsorption capacity decreased with increasing ionic strength and increasing chromatographic flow rate. Adsorption kinetics of urease onto poly(HEMA-GMA)-IDA-Ni(II) cryogel was also investigated and it was found that Langmuir adsorption model is applicable for this adsorption study. This novel immobilized metal affinity chromatography support was used 10 times without any decrease at their adsorption capacity. It was also observed that urease enzyme was repeatedly adsorbed and desorbed without significant lost in enzymatic activity.     

水杨酸型螯合吸附材料对重金属离子的吸附性能

将5-氨基水杨酸接枝到PGMA/SiO2微粒的聚甲基丙烯酸缩水甘油酯(PGMA)大分子链上,成功制备了一种新型螯合吸附材料ASA-PGMA/SiO2。采用静态法研究了ASA-PGMA/SiO2对重金属离子Cu2+、Cd2+、Zn2+、Pb2+的吸附性能,结果表明其对Cu2+、Cd2+、Zn2+、Pb2+具有很强的螯合吸附能力,吸附容量分别可以达到0.42、0.40、0.35、0.31mmol/g。体系的pH对吸附容量影响较大,吸附行为服从Langmuir和Freundlich吸附模型。使用0.1mol/L的盐酸溶液就可实现重金属离子的解吸。通过反复吸附-解吸实验证明ASA-PGMA/SiO2具有良好的重复使用性能。     

DNA adsorption via Co(II) immobilized cryogels

The separation and purification of important biomolecule deoxyribonucleic acid (DNA) molecules are extremely important. The adsorption technique among these methods is highly preferred as the adsorbent cryogels are pretty much used due to large pores and the associated flow channels. In this study, the adsorption of DNA via Co(II) immobilized poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) [poly(HEMA-GMA)] cryogels was performed under varying conditions of pH, interaction time, initial DNA concentration, temperature, and ionic strength. For the characterization of cryogels; swelling test, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), surface area (BET), elemental and ICP-OES analysis were performed. L-lysine amino acid was chosen as Co(II)-chelating agent and the adsorption capacity of cryogels was determined as 33.81 mg DNA/g cryogel. Adsorption of pea DNA was studied under the optimum adsorption conditions and DNA adsorption capacity of cryogels was found as 10.14 mg DNA/g cryogel. The adsorption process was examined via Langmuir and Freundlich isotherm models and the Langmuir adsorption model was determined to be more appropriate for the DNA adsorption onto cryogels.     

A chelating resin containing trihydroxybenzoic acid as the functional group: synthesis and adsorption behavior for Th(IV) and U(VI) ions

A novel glycidyl methacrylate chelating resin has been synthesized through copolymerization of glycidyl methacrylate (GMA) in the presence of divinylbenzene (DVB), the resulting resin was immobilized with 3,4,5-trihydroxybenzoic acid (THBA) to give GMA/DVB/THBA chelating resin. The adsorption of Th(IV) and U(VI) on GMA/DVB/THBA adsorbent was studied as a function of initial concentration, pH, shaking time and temperature. The novel chelating resin shows a high capacity for Th(IV) and U(VI), maximum adsorption of Th(IV) and U(VI) were 56 and 83.6 mg/g, respectively. Kinetic studies showed that the adsorption follows the pseudo second order model referring to the influence of the textural properties of the resin on the rate of adsorption. Thermodynamic parameters such as ?H° and ?S° were studied and indicated an endothermic process.     

Laterite clay-based geopolymer as a potential adsorbent for the heavy metals removal from aqueous solutions

This study is focused on the investigation of low iron lateritic clay-based geopolymer as a potential adsorbent for the higher uptake of Ni(II) and Co(II) ions from aqueous solutions. BET analysis revealed that the sieved geopolymer sample (SGS) was characterized by 17.441 m²/g of surface area, 0.005 cm³/g of pore volume, and 13.549 Å of pore diameter. SEM investigation confirmed the presence of pores and cavities onto the surface of SGS. XRD analysis showed that the geopolymer is semi-crystalline in nature. It was found that the adsorption ability of SGS remained 520 mg/g for Ni(II) ions and 500 mg/g for Co(II) ions when 0.5 M solutions were stirred with SGS for 60 min. The temperature and pH of the solution were maintained at 60 °C and 7.0, respectively. The adsorption data of both heavy metal (HM) ions fitted best in the pseudo-second-order kinetic model. The low activation energy value i.e. 2.507 kJ/mol for Ni(II) ions and 2.286 kJ/mol for Co(II) ions confirmed adsorption is physisorption. Adsorption data were tested with Langmuir and Freundlich models, the data showed comparatively better fitting in the Freundlich model. The greater value of monolayer adsorption capacity (Xm) for Ni(II) ions was found 1.77 × 10⁻² mol/g while for Co(II) ions it remained 1.69 × 10⁻² mol/g confirming the better interaction of metal ions with the adsorbent surface. Negative values of ΔG° confirmed the spontaneity of the process while the positive value of ΔS° showed the randomness of adsorbate particles. The positive value of ΔH° showed that the adsorption process remained endothermic for both HM ions. The experimental results confirmed the ability of laterite clay-based geopolymer for better removal of HM ions and hence can be employed for the wastewater treatment processes at low-cost adsorbent.     

亲水性氨基吡啶树脂的合成及其吸附性能

将氨基吡啶功能基引入亲水性大孔球状聚甲基丙烯酸环氧丙酯（PGMA）,合成了高亲水性的氨基吡啶螯合树脂(PGMA-AP),考察了该树脂对Hg²⁺、Pb²⁺、Cu²⁺、Ni²⁺等重金属离子的静态吸附性能及影响因素。 结果表明,该树脂对上述4种重金属离子在25 ℃时的静态饱和吸附容量分别为2.145、1.715、1.023和0.654 mmol/g,最佳吸附pH值为4.5～5.0,吸附性能随温度升高而改善,在实验浓度范围内该树脂对上述重金属离子的等温吸附符合Langmuir和Freundlich方程。     

Dye attached poly(hydroxyethyl methacrylate) cryogel for albumin depletion from human serum

Cibacron Blue F3GA was immobilized on poly(hydroxyethyl methacrylate) cryogel and it was used for selective and efficient depletion of albumin from human serum. The poly(hydroxyethyl methacrylate) was selected as the basic component because of its inertness, mechanical strength, chemical and biological stability, and biocompatibility. Cibacron Blue F3GA was covalently attached to the poly(hydroxyethyl methacrylate) cryogel to produce poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel affinity column. The poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was characterized with respect to gelation yield, swelling degree, total volume of macropores, Fourier Transform Infrared spectroscopy, and scanning electron microscopy. It was found that the maximum amount of adsorption (343 mg/g of dry cryogel) obtained from experimental results is very close to the calculated Langmuir adsorption capacity (345 mg/g of dry cryogel). The maximum adsorption capacity for poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel column was obtained as 950 mg/g of dry cryogel for nondiluted serum. The adsorption capacity decreased with increasing dilution ratios while the depletion ratio of albumin remained as 77% in serum sample. Finally, the poly(hydroxyethyl methacrylate)-Cibacron Blue F3GA cryogel was optimized for using in the fast protein liquid chromatography system for rapid removal of the high abundant proteins from the human serum.     

Gelatin-Immobilised Poly(hydroxyethyl methacrylate) Cryogel for Affinity Purification of Fibronectin

In this work, fibronectin purification from human plasma with the gelatin-immobilised poly(hydroxyethyl methacrylate) (PHEMA) cryogel has been evaluated. The PHEMA cryogel was prepared by cryo-polymerisation which proceeds in an aqueous solution of monomer frozen inside a plastic syringe. The PHEMA cryogel contained interconnected macrochannels of 10–200 μm in diameter. Gelatin molecules were covalently immobilised onto the PHEMA cryogel via carbodiimide activation. The gelatin-immobilised PHEMA cryogel was used to purify fibronectin from human plasma. Fibronectin adsorption from human plasma on the PHEMA cryogel was 0.30 mg/ml, while much higher adsorption values, up to 38 mg/ml, was obtained with the gelatin-immobilised PHEMA cryogel. The fibronectin adsorption capacity of the gelatin-immobilised PHEMA cryogel did not change with an increase in the flow rate of plasma. Up to 92 % of the adsorbed fibronectin was eluted using 2 M urea containing 1 M NaCl as elution agent. The adsorption–elution cycle was repeated ten times using the same PHEMA cryogel. No remarkable decrease was detected in the adsorption capacity of the gelatin-immobilised PHEMA cryogel.     

Preparation,characterization, and binding profile of imprinted semi-IPN cryogel composite for aluminum

Human body is greatly exposed to aluminum due to its high abundance in the environment. This nonessential metal is a threat to the patients of chronic renal disorders, as it is easily retained in their plasma and quickly accumulates in different tissues. Thus, there is great need to remove it from the aqueous environment. In this study, Al³⁺ imprinted semiinterpenetrating polymer network (semi-IPN)-based cryogel composite was prepared and applied for the purification of environmental and drinking water samples from aluminum. Poly (2-hydroxyethyl methacrylate) (pHEMA) discs were produced via cryogenic treatment and imprinted semi-IPN was introduced to the 3-(trimethoxysilyl) propyl acrylatemodified macroporous cryogel discs. The adsorption properties and selectivity of the aluminum (III) imprinted semi-IPN cryogel composite were studied in detail. The imprinted semi-IPN cryogel composite showed good selectivity towards aluminum (III) ions with the imprinting factor (IF) of 76.4 in the presence of competing copper (II), nickle (II), and iron (III) ions. The maximum adsorption capacity of 271 μmol g^-1 was obtained for aluminum (III) at pH 7.0 within 10 min using imprinted semi-IPN cryogel composite. The good selectivity and reusability of aluminum (III)-imprinted semi-IPN cryogel composite makes this material an eligible candidate for the purification of drinking water from aluminum (III) leaving important minerals remained in the water.     

Oriented immobilized anti‐hIgG via Fc fragment‐imprinted PHEMA cryogel for IgG purification

Antibodies are used in many applications, especially as diagnostic and therapeutic agents. Among the various techniques used for the purification of antibodies, immunoaffinity chromatography is by far the most common. For this purpose, oriented immobilization of antibodies is an important step for the efficiency of purification step. In this study, F_c fragment‐imprinted poly(hydroxyethyl methacrylate) cryogel (MIP) was prepared for the oriented immobilization of anti‐hIgG for IgG purification from human plasma. Non‐imprinted poly(hydroxyethyl methacrylate) cryogel (NIP) was also prepared for random immobilization of anti‐hIgG to compare the adsorption capacities of oriented (MIP/anti‐hIgG) and random (NIP/anti‐hIgG) cryogel columns. The amount of immobilized anti‐hIgG was 19.8 mg/g for the NIP column and 23.7 mg/g for the MIP column. Although the amount of immobilized anti‐hIgG was almost the same for the NIP and MIP columns, IgG adsorption capacity was found to be three times higher than the NIP/anti‐hIgG column (29.7 mg/g) for the MIP/anti‐hIgG column (86.9 mg/g). Higher IgG adsorption capacity was observed from human plasma (up to 106.4 mg/g) with the MIP/anti‐hIgG cryogel column. Adsorbed IgG was eluted using 1.0 m NaCl with a purity of 96.7%. The results obtained here are very encouraging and showed the usability of MIP/anti‐hIgG cryogel prepared via imprinting of Fc fragments as an alternative to conventional immunoaffinity techniques for IgG purification. Copyright © 2012 John Wiley & Sons, Ltd.     

Removal of Th(IV), Ni(II)and Fe(II) from aqueous solutions by a novel PAN–TiO<Subscript>2</Subscript> nanofiber adsorbent modified with aminopropyltriethoxysilane

A novel polyacrylonitrile (PAN)–titanium oxide (TiO₂) nanofiber adsorbent functionalized with aminopropyltriethoxysilane (APTES) was fabricated by electrospinning. The adsorbent was characterized by SEM, FTIR, TEG and BET analyses. The pore diameter and surface area of the adsorbent were 3.1 nm and 10.8 m² g^?1, respectively. The effects of several variables, such as TiO₂ and amine contents, pH, interaction time, initial concentration of metal ions, ionic strength and temperature, were studied in batch experiments. The kinetic data were analyzed by pseudo-first-order, pseudo-second-order and double-exponential models. Two isotherm models, namely Freundlich and Langmuir, were used for analysis of equilibrium data. The maximum adsorption capacities of Th(IV), Ni(II) and Fe(II) by Langmuir isotherm were found to be 250, 147 and 80 mg g^?1 at 45 °C with pH of 5, 6 and 5, respectively, and greater adsorption of Th(IV) could be justified with the concept of covalent index and free energy of hydration. Calculation of ΔG°, ΔH° and ΔS° demonstrated that the nature of the Th(IV), Ni(II) and Fe(II) metal ions adsorption onto the PAN–TiO₂–APTES nanofiber was endothermic and favorable at a higher temperature. The negative values of ΔG° for Th(IV) showed that the adsorption process was spontaneous, but these values for Ni(II)and Fe(II) were positive and so the adsorption process was unspontaneous. Increasing of ionic strength improved the adsorption of Ni(II) and Fe(II) on nanofiber adsorbent but decreased the adsorption capacity of Th(IV). The adsorption capacity was reduced slightly after six cycles of adsorption–desorption, so the nanofiber adsorbent could be used on an industrial scale. The inhibitory effect of Ni(II) and Fe(II) on the adsorption of Th(IV) was increased with an increase in the concentration of inhibitor metal ions.     

A Crosslinked Carboxylic Acid Containing Cation Exchange Monolithic Cryogel for Human Serum Albumin Separation

For this work, we synthesized poly(N-isopropylacrylamide-acrylamide)-acrylic acid (poly(NIPAM-Am)-AAc) monolithic cryogel for a human serum albumin separation (HSA) from a protein mixture (human serum immunoglobulin, human serum albumin and lysozyme) and performed HSA adsorption studies using the cryogel to do continuous system experiments in a syringe column connected by a peristaltic pump. Poly(NIPAM-Am)-AAc with a pore size of 10–100 μm was produced by free radical polymerization that proceeded in an aqueous solution of monomers frozen inside a syringe column. The monolithic poly(NIPAM-Am)-AAc cryogel was characterized by performing swelling studies, FTIR and SEM that showed a swelling ratio of 6.2 g H₂O/g dry cryogel. The maximum HSA adsorption by the cryogel was 42.5 mg/g polymer at pH 4.0 in a 50 mM acetate buffer. We also studied the effect of two different temperatures (25 and 40°C). The higher temperature increased the adsorption capacity of the cryogel. HSA molecules could be reversibly adsorbed and desorbed five times with the same poly(NIPAM-Am)-AAc cryogel without a noticeable loss of their HSA adsorption capacity. The synthesized cryogel was used to separate albumin from the protein mixture. Adsorbed albumin was eluted by changing the pH of the buffer (pH 7.0 and 25°C). Poly(NIPAM-Am)-AAc monolithic cryogel behaved as a cation exchange column because of its functional carboxylic group.     

亚氨二乙酸型复合材料IDAA-PGMA/SiO2对重金属及稀土离子的吸附行为与吸附热力学

将甲基丙烯酸缩水甘油酯(GMA)接枝于硅胶微粒表面,制得了接枝微粒PGMA/SiO₂; 使亚氨二乙酸(IDAA)与接枝PGMA的环氧基团发生开环反应, 从而将亚氨二乙酸基团引入接枝微粒表面, 制得了复合螯合微粒材料IDAA-PGMA/SiO₂. 本文研究了IDAA-PGMA/SiO₂对重金属及稀土离子的螯合吸附行为, 深入地研究了吸附机理与吸附热力学. 研究结果表明: 凭借亚氨二乙酸基团与重金属离子之间的静电作用与配位螯合作用的协同, 复合微粒材料IDAA-PGMA/SiO₂对重金属离子可产生强的螯合吸附作用, 尤其对Pb²⁺离子表现出很强的螯合吸附能力, 常温下吸附容量可达0.235 g·g^-1; IDAA-PGMA/SiO₂对重金属离子的吸附过程为一放热过程, 且为焓驱动的过程, 升高温度, 吸附容量降低; 对稀土离子的吸附过程则为熵驱动的过程; 在可抑制金属离子水解的pH范围内, 介质的pH值越高, IDAA-PGMA/SiO₂的螯合吸附能力越强; IDAA-PGMA/SiO₂对重金属离子的吸附容量远高于对稀土离子的吸附容量.     

Hemoglobin binding from human blood hemolysate with poly(glycidyl methacrylate) beads

Metal-chelating affinity beads have attracted increasing interest in recent years for protein purification. In this study, iminodiacetic acid (IDA) was covalently attached to the poly(glycidyl methacrylate) [PGMA] beads (1.6 μm in diameter). Cu(2+) ions were chelated via IDA groups on PGMA beads for affinity binding of hemoglobin (Hb) from human blood hemolysate. The PGMA beads were characterized by scanning electron microscopy (SEM). The PGMA-Cu(2+) beads (628 μmol/g) were used in the Hb binding-elution studies. The effects of Hb concentration, pH and temperature on the binding efficiency of PGMA-Cu(2+) beads were performed in a batch system. Non-specific binding of Hb to PGMA beads in the absence of Cu(2+) ions was very low (0.39 mg/g). The maximum Hb binding was 130.3 mg/g. The equilibrium Hb binding increased with increasing temperature. The negative change in Gibbs free energy (ΔG°<0) indicated that the binding of Hb on the PGMA-Cu(2+) beads was a thermodynamically favorable process. The ΔS and ΔH values were 102.2 J/mol K and -2.02 kJ/mol, respectively. Significant amount of the bound Hb (up to 95.8%) was eluted in the elution medium containing 1.0 M NaCl in 1 h. The binding followed Langmuir isotherm model with monolayer binding capacity of 80.3-135.7 mg/g. Consecutive binding-elution experiments showed that the PGMA-Cu(2+) beads can be reused almost without any loss in the Hb binding capacity. To test the efficiency of Hb depletion from blood hemolysate, eluted portion was analyzed by fast protein liquid chromatography. The depletion efficiency for Hb was above 97.5%. This study determined that the PGMA-Cu(2+) beads had a superior binding capacity for Hb compared to the other carriers within this study.     

Histidine-epoxy-activated sepharose beads embedded poly (2-hydroxyethyl methacrylate) cryogels for pseudobiospecific adsorption of human immunoglobulin G

The use of highly purified immunoglobulin became among the most powerful adopted strategies in therapeutic trials nowadays. Their role as immunomodulatory and anti-inflammatory agents has widened their scope of use. A novel continuous supermacroporous monolithic cryogels embedded with histidine-epoxy-activated-sepharose beads were synthetized as a new monolithic adsorbents for the separation of immunoglobulin G from human serum. The histidine-epoxy-activated-sepharose beads were embedded into the 2-hydroxyethyl methacrylate (HEMA) cryogels present in frozen aqueous solution inside a plastic syringe. The microstructure morphology of the cryogels was characterized by swelling measurement and scanning electron microscopy. The adsorption of human IgG on the histidine-epoxy-activated-sepharose beads pHEMA cryogels appeared to follow the Langmuir–Freundlich adsorption isotherm model. The maximum IgG adsorption was observed at 4°C and pH 7.4 and was found to be 26.95 mg/g of cryogel which is close to that obtained experimentally (24.49 mg/g). The cryogels were used for several adsorption-desorption cycles without any negligible decrease in their adsorption capacity.     

Purification of Papain Using Reactive Green 5 Attached Supermacroporous Monolithic Cryogel

Supermacroporous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] monolithic cryogel was prepared by radical cryocopolymerization of HEMA with N,N??-methylene bisacrylamide as crosslinker. Reactive Green 5 dye was immobilized to the cryogel with nucleophilic substitution reaction, and this dye attached cryogel column was used for affinity purification of papain from Carica papaya latex. Reactive Green 5-immobilized poly(HEMA) cryogel was characterized by swelling studies, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis. Maximum papain adsorption capacity was found to be 68.5?mg/g polymer while nonspecific papain adsorption onto plain cryogel was negligible (3.07?mg/g polymer). Papain from C. papaya was purified 42-fold in single step with dye attached cryogel, and purity of papain was shown by silver-stained sodium dodecyl sulfate?Cpolyacrylamide gel electrophoresis.     

Adsorption of cadmium ions from aqueous solutions using nano-montmorillonite: kinetics,isotherm and mechanism evaluations

With increasing industrial development, heavy metal pollution, e.g., cadmium (Cd) pollution, is increasingly serious in soil and water environments. This study investigated the sorption performance of nano-montmorillonite (NMMT) for Cd ions. Adsorption experiments were carried out to examine the effects of the initial metal ion concentration (22.4–224 mg/L), pH (2.5–7.5), contact time (2–180 min) and temperature (15–40 °C). A simulated acid rain solution was prepared to study the desorption of Cd adsorbed on NMMT. After the adsorption or desorption process, the supernatant was analyzed using a flame atomic absorption spectrometry method. The Cd removal rate increased as the pH and contact time increased but decreased as the initial metal ion concentration increased. The maximum adsorption capacity was estimated to be 17.61 mg/g at a Cd²⁺ concentration of 22.4 mg/L. The sorption process can be described by both the Langmuir and Freundlich models, and the kinetic studies revealed that the pseudo-second-order model fit the experimental data. The Cd desorption rate when exposed to simulated acid rain was less than 1%. NMMT possesses a good adsorption capacity for Cd ions. Additionally, ion exchange was the main adsorption mechanism, but some precipitation or surface adsorption also occurred.     

Polymer brushes grafted from graphene via bioinspired polydopamine chemistry and activators regenerated by electron transfer atom transfer radical polymerization

Polymer brushes decorated reduced GO (rGO) with advanced applications have been prepared by bioinspired polydopamine (PDA) chemistry integrated with activators regenerated by electron transfer atom transfer radical polymerization (ARGET‐ATRP) technique. First, rGO/PDA was obtained by the process for graphene oxide (GO) coated with a homogeneous bio‐adhesive PDA layer. Then the initiator 2‐bromoisobutyryl bromide (BIBB) was immobilized on the surface of PDA functionalized rGO. Finally, rGO/PDA‐Br was polymerized with N, N‐diethylaminoethyl methacrylate (DEAEMA) and glycidyl methacrylate (GMA) to obtain rGO/PDA‐g‐polymer brushes by ARGET‐ATRP process. The prepared rGO/PDA‐g‐PGMA brush would be subjected to further functionalization with ethylenediamine (EDA), which would impart the obtained products (rGO/PDA‐g‐PGMA‐NH₂) with good adsorption ability toward cationic dyes. The chemical structures and morphologies of the functionalized GO products have been characterized in detail by Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope(TEM), and atomic force microscopy (AFM). The distinctive pH‐responsive character of rGO/PDA‐g‐PDEAEMA and adsorption ability of rGO/PDA‐g‐PGMA‐NH₂ for cationic dyes have been explored by UV–vis spectrophotometer. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 689–698     

Creatinine imprinted poly(hydroxyethyl methacrylate) based cryogel cartridges

Creatinine imprinted cryogel (MIP) cartridge was prepared with functional monomer N-methacryloyl-(L)-histidinemethylester (MAH) under frozen conditions. Creatinine adsorption studies and selectivity of MIP cryogel were evaluated in aqueous solution and artificial urine sample. Maximum adsorbed amount of creatinine was calculated as 6.83 mg/g polymer for MIP cryogel. Langmuir and Freundlich adsorption isotherm models were used to investigate the adsorption behaviour of creatinine. In the artificial urine sample; recovery amounts of creatinine were found 34.7–46.2%. Creatinine imprinted cryogel (MIP) cartridge recognized creatinine, 4.58 and 4.37 times greater competitive molecules. MIP cryogel catridge was repeatedly used many times for adsorption desorption cycles.     

Cadmium sorption properties of poly(vinyl alcohol)/hydroxyapatite cryogels: I. kinetic and isotherm studies

A new adsorbent for removing heavy metal ions from wastewater, poly(vinyl alcohol)/hydroxyapatite(PVA/HAp) composite cryogel, has been investigated. The PVA/HAp cryogel was prepared through a clean process by using water and freeze-thawing. The PVA/HAp cryogel is provided with interconnected macropores varying from 0.1 um to several um and well dispersed and immobilized HAp in cryogel. Batch experiments of cadmium sorption were carried out to test the sorption ability of PVA/HAp cryogel. The isotherm and kinetics of cadmium sorption were studied by fitting the experimental results to isotherm and kinetics models. The Langmuir isotherm suitable for this system shows the maximum sorption capacity of 53.3 mg/g. For kinetics, the double-exponential model presents best fit compared with pseudo-first-order and pseudo-second-order models. The double-exponential model indicates a diffusion-controlled and a two-step mechanism.