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In agriculture, fertilizers are important for plant growth. Among them, conventional fertilizers, particularly urea fertilizers, are popular owing to their low cost and high nitrogen content. However, their use often leads to uneven nitrogen absorption and environmental pollution. Slow-release fertilizers (SRFs), particularly those based on chitosan, offer a solution. This research aims to produce biodegradable chitosan/citric acid/calcium–urea (CS/St/Ca–urea) films to increase the absorption efficiency and use of artificial nitrogen fertilizers (especially urea). Herein, chitosan/citric acid/calcium (CS/St/Ca) films were synthesized and applied as SRFs. Chitosan was dissolved in 1 % acetic acid and added to citric acid at 55 °C for 24 h. Then, calcium oxide (CaO) and urea were added to the CS/St mixture and stirred until homogeneous. Subsequently, the membrane product was characterized by ATR–IR, SEM–EDX, and elemental analysis and its nitrogen solubility was determined using a UV–vis spectrophotometer. The physical properties of the CS/St/Ca were investigated via swelling, hydrophobicity, and tensile strength tests. Results showed that a CS/St at weight ratio of 1:1 can increase the tensile strength by up to 13.6 %. The addition of a filler with a Ca additive, as well as the addition of CaO, can increase the mechanical strength of the membrane. The CS/St/Ca film membranes can function optimally as a urea SRF coating material with a release rate of 3.37–9.46 ppm day−1. The applied kinetic model follows the Higuchi kinetic model, with an R2 value of 0.9505.

The textile industry in the world keeps increasing, but it harms environmental pollution caused by textile dye waste. Synthetic dyes contain carcinogenic and mutagenic ingredients that can demage the environment and aquatic biota. The alternative to handling dye pollution with a low-cost method is adsorption using nitric acid-activated coconut fiber. Coconut fiber was an abundant agricultural waste and economical, and it had an active site that contained many compounds such as cellulose, lignin, pyroligneous acid, and tannin molecules. This study used the UV-Vis Spectrophotometer analysis method to determine the effect of pH, contact time, and coconut fiber on the adsorption capacity of methylene blue. The result showed that the optimal conditions for adsorption were a pH of 5, a contact time of 75 minutes, and a percentage adsorption of the variation of contact time of 99.628%. The adsorption study was according to a pseudo-second-order reaction with a constant reaction rate of 0.050 g mg-1 minute-1. The maximum adsorption capacity was 2 mg g-1, with the percentage of methylene blue adsorbed at 99.84%. Adsorption occurs chemically with an energy of 35.4 kJ mol-1, so it can be determined that it occurs with a monolayer mechanism.

This study analyzed MeHg in a fast, simple, low-waste, and accurate by using ultra-high liquid chromatography coupled with inductively coupled plasma mass spectrometry. Simple preparation by liquid extraction with sonication at room temperature was effective extract MeHg from Certified Reference Material (CRM) and shark meat samples. Effective MeHg separation was achieved in less than 300 s using a C18 Hypersil Gold analytical column with a mobile gradient phase of 0.5% (w/v) L-cysteine in 2% (v/v) HNO3 and 100% methanol. The MeHg was extracted from 100 mg of shark meat using 1 mL of 0.5% (w/v) L-cysteine in 2% (v/v) HNO3 and sonicated for 30 min. Analysis of certified reference material (DORM-4) showed values between the experimental and certified values. The observed limit of detection and quantification MeHg were 0.86 and 2.85 pg/L, respectively. This method was applied to measure MeHg in shark meat from Binuangeun areas. The MeHg concentration in Rhizoprionodon acutus was 0.22–0.63 mg/kg wet weight (w.w.), Squalus hemipinis 0.68–1.14 mg/kg w.w., and 0.29–1.22 mg/kg w.w. for Sphyrna lewini. This study provides a quick and easy method to evaluate MeHg in shark meat or other seafood products and applies to many samples in a single assay.

This study aims to examine the potential of p-tert-butylkalix[4]arene derivatives, namely 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrahydroxy-calix[4]arene (TBCA), and 5,11,17,23-tetra-tert-butyl-25-monohydroxy-26,27,28-tribenzoyloxycalix[4]arene (TBMTCA) as adsorbent for metal cations, such as Pb(II) and Fe(III). The synthesized compounds were characterized using FT-IR and 1H-NMR spectroscopy. The adsorption studies were then carried out with contact time as a parameter, while the kinetics were evaluated using the Lagergren and Ho-McKay equations. The isotherms were analyzed using the Langmuir and Freundlich equations. For the kinetics of TBCA adsorbents, Pb(II) cations followed the Ho-McKay model, while Fe(III) was based on Lagergren. Furthermore, for the TBMTCA adsorbent, Pb(II) followed the Lagergren kinetic model, while Fe(III) was based on the Ho-McKay. The cation adsorption isotherms of Pb(II)-TBCA, Pb(II)-TBMTCA, Fe(III)-TBCA, and Fe(III)-TBMTCA are more in line with the Langmuir model. These results indicate that they can be used as heavy metal adsorbents, and recycled to increase their economic value.

The combination of polystyrene and chitosan can form polyelectrolyte (PE) membranes. Polystyrene sulfonate-chitosan (PSS-chitosan) adsorbent membrane can adsorb dodecyl benzene sulfonate (DBS) in laundry wastewater. This study aimed to synthesize, identify characteristics, and formulate adsorption effectiveness by PSS-chitosan membranes. The research methods included converting polystyrene into PSS, isolating chitosan, optimizing geometry, making PSS-chitosan membranes, studying adsorption, and applying membranes to laundry wastewater. The resulting membrane was characterized using FTIR and SEM. The results of the infrared spectra showed vibrations of –OH and –NH2 groups at 3418 cm–1, while the SEM image showed a homogeneous membrane surface. The quality of chitosan isolation from shrimp shells was indicated by the degree of deacetylation of 61.3%. The results of the geometry optimization showed the change in the structure’s total energy after adsorption. The PSS-chitosan membrane is resistant to acids but decomposes under alkaline conditions. Optimum adsorption of PSS-chitosan membrane on DBS occurred at pH 8 for 100 minutes. The adsorption kinetics of the PSS-chitosan membrane follows the first pseudo-order equation. PSS-chitosan membrane adsorption isotherm follows the Langmuir isotherm model with an adsorption capacity and efficiency of 3.97 mg.g–1 and 76.6%, respectively, at 0.6 ppm. At the application stage, the PSS-chitosan membrane could adsorb DBS in laundry wastewater by (62.4 ± 7.2) %.

Carbon/Alginate/Chitosan Composite (CAC) as a sorbent for solid-phase extraction of Cu(II) (pre-concentration) with atomic absorption spectrometry for analysis was successfully prepared. The sorbent was made with a mass ratio of chitosan:alginate:carbon = 1:1:1. CAC sorbents were characterized using FTIR for functional group analysis while SEM-EDX characterization was performed to determine surface morphology and percentage of elements. SPE parameters were optimized for adsorption-desorption efficiency under various conditions, i.e. of pH 5, Cu(II) concentration of 4 mg/L, the flow rate of Cu(II), and Na2EDTA eluent at 5 mL/min, the volume of Cu(II) sample and Na2EDTA eluent 25 mL and 1.0 M of Na2EDTA eluent concentration. Applying CAC-based SPE for Cu(II) analysis in water samples at optimum conditions gave 80.9–83.6% recovery. In bottled drinking water samples, a pre-concentration factor of 2.5–5 times was obtained, and the Cu(II) concentration of 0.017–0.020 mg/L was detected.

This study aims to investigate the application of two calix[4]arene derivatives named 5,11,17,23-tetra-(t-butyl)-25,26,27,28-tetrahydroxycalix[4]arene (TBCA) and 5,11,17,23-tetra-(t-butyl)-26,27,28-tribenzoyloxycalix[4]arene (TBMTCA) as adsorbents of Pb(II) from aqueous solution in a batch system. Adsorption was carried out by varying pH solution, exposure time, and concentration. The kinetics was evaluated based on the adsorption in various exposure times using the Lagergren and Ho equations, while the isotherms were analyzed based on the adsorption in various Pb(II) concentrations using the Langmuir and Freundlich equations. Furthermore, the isotherm model showed the Pb(II) adsorption of TBCA and TBMTCA followed Langmuir model with a capacity of 137.29 and 128.46 mg/g, respectively. Based on the adsorption capacity, both adsorbents are the potential for the removal of heavy metal cations from polluted water.

Poly(ethyl eugenyl oxyacetate) (PEEOA) had been synthesized for separating heavy metals like Fe(III), Cr(III), Cu(II), Ni(II), Co(II), and Pb(II) by liquid membrane transport method. The effects of pH, ion carrier volume, stripping concentration, transport time, and metal ion concentration were investigated to obtain optimum conditions. Experimental results showed that optimum pH occurred at pH 4 for Fe(III) ions and pH 5 for others. Carrier volumes were optimum at 8.5 mL for Fe(III) and Pb(II) ions but 7.5 mL for others. The optimum concentrations of the stripping phase were 2 M for Fe(III) and Cu(II) ions, 1 M for Cr(III), Ni(II), Co(II) ions, and 0.5 M for Pb(II) ion. Transport times were optimum at 36 h for Fe(III) and Co(II) ions and 48 h for others. The optimum metal ion concentrations were 0.25 mM for Fe(III) and Cr(III) ions, while other ions were 0.1 mM. The response of PEEOA to Fe(III) ion was the best with selectivity order, Fe(III) > Cr(III) > Pb(II) > Cu(II) > Ni(II) > Co(II). PEEOA also could separate Fe and Ni in a ferronickel sample whose transport percents were 8.87 and 0.92%, respectively. Hence, PEEOA is reasonably effective as an ions carrier for separating metal ions individually or ionic mixture and also in a ferronickel compound.

Metals accumulation in threatened sharks’ meat represents a global health issue. The objective of the current study was to measure the concentration of six metals (Li, Ti, Ni, Cd, As, and Pb) using ICP-MS in threatened sharks’ meat of Rhizoprionodon acutus, Squalus hemipinnis, and Sphyrna lewini from Binuangeun Fish Auction in Lebak, Banten, Indonesia. The results showed that the concentration of Ni, Li, Cd, and Pb was below the acceptable levels for food sources for human consumption, except for As concentration (more than 30 fold higher). This study showed high levels of Ti concentration in all threatened sharks' meat. Overall, this study shows that an accumulation of Ti in sharks' meat should be considered a risk to the health of seafood consumers.

In this work, tartrate-capped silver nanoparticles (AgNPs) by reducing Ag+ ions into Ag0 using L-ascorbic acid and capping disodium tartrate have been prepared. The reaction was carried out at room temperature in an alkaline medium of pH 11 to obtain a rapid and one-step green synthesis method. The effect of L-ascorbic acid concentration on the synthesis preparation was studied to investigate their impact on the particle size, morphology, and stability of the AgNPs. The obtained tartrate capped AgNPs have SPR absorbance in 390–410 nm. They have a spherical shape, as confirmed by TEM. Increasing L-ascorbic acid concentrations from 25 mM to 100 and 200 mM leads to the 27, 17, and 11 nm particle size distributions. They give the zeta potential of –33.5, –20.8, and –21.3, respectively. After a week, the decreasing absorbance peaks were 0.151, 0.0105, and 0.336 a.u. The optimum L-ascorbic acid concentration was obtained at 100 mM, indicated by the smallest FWHM point. Thus, we may conclude that lower or higher levels of reducing agents resulted in low stability. Therefore, controlling L-ascorbic acid concentration is an important parameter. A sufficient concentration and an appropriate capping agent can produce good nanoparticle stability essential for further application.

In this study, a superparamagnetic composite of magnetite-cetyltrimethylammonium bromide (CTAB) has been prepared by the coprecipitation method and then applied as a charge-selective adsorbent of anionic methyl orange (MO). The VSM (Vibrating Sample Magnetometer) measurement suggests the superparamagnetic property of MNPs (Magnetite Nano Particles) with a magnetic saturation of 49.2 emu g–1. The SEM image exhibits the significant difference in particle size from nanometers in uncoated magnetite to micrometers in magnetite-CTAB. Calculations with ImageJ software indicate that the diameter of the composite is in the range of 2–13 µm, with an average diameter of 6.56 µm, possibly consisting of hundreds to thousands of magnetite-CTAB micelles. The adsorption kinetics of MO over magnetite-CTAB follows the pseudo-second-order adsorption model of Ho and McKay with a rate constant (k2) of 3.54 × 103 g mol–1 min. The adsorption isotherm is well described by the Langmuir model with a Langmuir constant (KL) of 7.46 × 104 L mol and a maximum capacity (qm) of 27.9 mg g–1. The developed material is intriguing because it can be easily and quickly recovered using an external magnet after adsorption and selectively adsorbs anionic dyes.

Kinetics parameters are the essential issue in the design of water treatment systems for pollutants uptake. Though numerous studies have identified the boundary conditions that exert influence on the kinetics parameters, the influence of the dynamic initial solute concentration (C0) to the kinetic parameters generated from fitting kinetics model to experimental data has not been investigated thoroughly. This study revealed a change in the kinetics parameter value due to changes in the adsorption mechanism as an effect of dynamic C0. It was observed that at higher C0 the adsorbed solute at equilibrium (qe) increases and it takes longer time to reach equilibrium. As a result, the kinetics rate constant (k) calculated from adsorption reaction model (Lagergren, Ho, Santosa, and RBS) was decreased. In general, Ho model exhibit higher correlation coefficient value (R2) among the other model at low C0. At high C0, Ho’s R2 tend to decrease while the Lagergren and RBS’s R2 was increased. The amendment mechanism from external mass transport to intra-particle diffusion as a rate limiting step was evidenced by Boyd and Weber-Morris kinetics model. Further, the physicochemical properties of the adsorbent used in this work: chitin and Fe3O4 modified horse dung humic acid (HDHA-Fe3O4 and HDHA-Ch, respectively) with the solute: Pb(II), Methylene Blue (MB), and Ni(II) was deeply discussed in this paper. The outcomes of this work are of prime significance for effective and optimum design for pollutant uptake by adsorption equipment. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Creatinine concentration is an essential indicator for assessing kidney function and diagnosing a disease. A selective and sensitive colorimetric detection was developed based on the EDTA-capped AgNPs aggregation to determine creatinine accurately. The developed method was optimized using response surface methodology (RSM) with Box-Behnken Design (BBD) model by studying pH, AgNPs concentration, and detection time as the critical parameters. The result showed that medium pH had the most crucial role in the interaction between EDTA-capped AgNPs and creatinine. The addition of creatinine to the colloidal EDTA-capped AgNPs induced the particle aggregation, followed by a color change from yellow (with lambda max 398 nm) to dark blue (with lambda max 650 nm) within 1 min of reaction at pH 12. The tautomerization of creatinine to its anionic amino species at alkaline pH, which cross-links the EDTA-capped AgNPs through the hydrogen bond networks with the negatively charged EDTA-capped AgNPs, occurs via an aggregation mechanism. The SPR absorbance ratio of A650/A398 was correlated to the creatinine concentration under the optimized conditions in the range of 0.0–3.0 μM with the limit of detection (LOD) of 0.0073 µM. The proposed method could offer simple, rapid, and inexpensive creatinine analysis for clinical diagnosis.

This study aims to examine the manufacture, characterization, and in vitro hemocompatibility of glutaraldehyde-crosslinked chitosan/carboxymethyl cellulose (CS/CMC-GA) as a hemodialysis membrane. The CS/CMC-GA membrane was prepared using the phase inversion method with 1.5% CS and 0.1% CMC. The chitosan was crosslinked with glutaraldehyde in various monomers ratios, and the membranes formed were characterized by FTIR, SEM, and TGA. Furthermore, the hydrophilicity, swelling, porosity, mechanical strength, and dialysis performance of the membranes against urea and creatinine were systematically examined, and their in-vitro hemocompatibility tests were also conducted. The results showed that the CS/CMC-GA membranes have higher hydrophilicity, swelling, porosity, mechanical strength, and better dialysis performance against urea and creatinine than chitosan without modification. In addition, the hemocompatibility test indicated that the CS/CMC-GA membranes have lower values of protein adsorption, thrombocyte attachment, hemolysis ratio, and partial thromboplastin time (PTT) than that of pristine chitosan. Based on these results, the CC/CMC-GA membranes have better hemocompatibility and the potential to be used as hemodialysis membranes.

Silica scaling is a common problem in geothermal power generation facilities which inhibits electricity generation. In order to provide a solution to this problem, the removal of silicate ions using CPEG-TOMAC (Chitosan-polyethylene glycol–trioctyl methyl ammonium chloride) membrane adsorbent was investigated for geothermal brine from Geo Dipa Energy, Dieng. The process is dependent on contact time, pH, and the concentration of silicate. An adsorption batch study that used adsorbents for the geothermal brine of the Dieng Geo Dipa reactor 28A showed that CPEG TOMAC at pH 6 resulted in an adsorption capacity of 72.6 mg g–1. Furthermore, the adsorption of silicate ions onto the membrane followed pseudo-second-order kinetics and the Freundlich isotherm model.

Anion logam berat Cr2O72– bersifat lebih toksik dibandingkan bentuk kationnya (Cr3+) yang dalam konsentrasi kecil dapat menyebabkan kanker bagi manusia. Salah satu cara yang paling sederhana dalam menyerap zat pencemar yaitu melalui adsorpsi. Senyawa C–4–etoksi–3–metoksifenilkaliks[4]resorsinarena trifenilfosfonium klorida (CKR) telah digunakan sebagai adsorben Cr2O72–. Dalam penelitian ini dilakukan karakterisasi adsorben CKR lebih lanjut dan interaksinya terhadap Cr2O72–. Metode penelitian yang dilakukan adalah (1) karakterisasi adsorben CKR meliputi titik lebur dan sifat kelarutannya; dan (2) studi spektroskopi CKR dan kompleks CKR–Cr2O72– serta desorpsi. Hasil penelitian menunjukkan CKR memiliki titik lebur 259,7°C dan mampu larut dalam aseton, etanol, metanol, dimetilformamida, dan dimetilsulfoksida serta terdistribusi di dalam air dengan baik. CKR berukuran pori 35,50 (mesopori) memiliki luas permukaan spesifik (SBET) sebesar 5,749 m2/g dan total volume pori 10,21×10–3 cc/g. Interaksi antara situs aktif gugus fosfonium kuarterner dengan Cr2O72– dalam kompleks CKR–Cr2O72–melalui pergantian unsur Cl pada CKR oleh Cr2O72–dengan prosentase massa sekitar 0,07%. Regenerasi adsorben CKR melalui desorpsi tunggal belum dapat membebaskan semua Cr2O72– yang telah terikat. Kemisorpsi CKR–Cr2O72– meliputi 13,16% pertukaran ion dan selebihnya diduga merupakan proses kelasi dengan interaksi logam–adsorben yang lebih kuat.

Crude oil is an indispensable energy feedstock for daily activities, although some amounts of metallic porphyrins components with undesired characteristics have been identified. These constituents are assumed to originate from the geochemical process of chlorophyll and heme derivatives. In addition, their chemical structures have been thoroughly characterized using spectroscopy techniques, while several analytical methods were adopted in the detection and concentration quantification in the crude oils. The metallic porphyrins have several demerits, including the deactivation of used catalysts, contamination of the treated petrochemical products, and corrosion of the industrial equipment. Also, the removal process is considered challenging due to the strong interaction with the asphaltene fraction of crude oil. This review article, therefore, provides brief information on the origin, physicochemical properties, and possible removal technology of metallic porphyrins from crude oil samples. Besides, a better understanding of chemistry contributes a useful insight towards the development and establishment of better futuristic processing technology.

An optical analytical sensor was proposed based on the complexation reactions of 1,10-phenanthroline derivative in aqueous solutions. This study aims to synthesize a metal ion sensor for detecting Fe(ll) ion from the immobilization of 1,10-phenanthroline compound in alginate/pectin film. This was carried out by characterizing the films using the Fourier-transform infrared spectrometry (FT-IR) and scanning electron microscope (SEM). The determination of the optimal condition for Fe(II) ion detection and validation of the parameters was conducted by measuring the absorbance of the films using a UV-Vis spectrophotometer. After the addition of Fe(II) ion, the color of the alginate/pectin-phenanthroline film changed from transparent yellow to orange-red, showing its potential as a visual colorimetric sensor for iron(II) ion. It was found that the optimum condition for Fe(II) ion sensing was at 513 nm after 2 min of detection at pH 2. The alginate/pectin-phenanthroline film had good linearity, precision, selectivity, and accuracy with a detection limit as low as 0.446 mg L–1, which was remarkable.

The activated carbon-chitosan-alginate (KKA) beads powder was synthesized to form an adsorbent for the cationic dyes, methylene blue (MB) and methyl violet 2B (MV 2B). The aims of this research were to determine the optimum composition of KKA beads powder for the adsorption of cationic dyes and to investigate the effect of pH, adsorbent mass, contact time, and initial concentration of MB and MV 2B dyes. A desorption study was also implemented to predict the adsorption mechanisms of MB and MV 2B dyes. The KKA beads powder was prepared by mixing chitosan, Na-alginate with various variation of masses (0.6; 0.8; 1.0; and 1.2 g) and activated carbon. The KKA beads were immersed in a CaCl2 solution. The KKA beads powder was characterized using FTIR spectroscopy and SEM. The desorption study was conducted in NaCl (0.1 M and 1.0 M), ethanol (40% and 60%), and pH 4 solution. The result showed that the KKA beads powder had been successfully created, with maximum adsorption capacities of 1.34 mmol g–1 for MB and 1.23 mmol g–1 for MV 2B. The kinetics and isotherms of MB and MV dyes adsorption on the KKA beads powder followed pseudo second order kinetics model and Freundlich isotherm. The desorption study showed that 60% ethanol was the most effective desorption solution for cationic dyes.

In this study, we successfully developed gold nanoparticles capped with histidine (His-AuNPs) for Hg2+ detection using trisodium citrate as the reducing agent. The optimum pH for the detection of Hg2+ by His-AuNPs was 12. The addition of Hg2+ to the His-AuNPs caused the color change from red to black-blue, which is readily detectable by the naked eye. This color change is followed by a decrease in the intensity of the primary Surface Plasmon Resonance (SPR) peak at a wavelength (λ) of 525 nm and an increase in the secondary peak at λ = 650 nm. His-AuNPs effectively detected Hg2+ with limits of detection and quantitation of 1.77 µM and 5.89 µM, respectively. His-AuNPs exhibited good performance for the detection of Hg2+ in waste water collected from a steel industrial facility in Banten Province, with a recovery and a percent relative standard deviation of 115% and 1.02%, respectively.

This study aims to investigate the synthesis and characterization of β-carotene encapsulated in the blending matrices of starch (native and hydrolyzed starch)-chitosan/TPP (tripolyphosphate) by examining the effects of starch-to-chitosan weight ratio, β-carotene addition level, and TPP addition level on the encapsulation efficiency (EE) and loading capacity (LC); and to evaluate their storage stability. The encapsulation was done by the dropwise addition of ethanolic β-carotene dispersion into the blending matrices. The results of XRD analysis show that the encapsulation process significantly decreases the crystallinity of the starches, chitosan, and β-carotene. Scanning electron microscope (SEM) images reveal that the encapsulation products form irregular lumps. The EE and LC tend to increase with the increase in polymer fraction of matrices and β-carotene addition level, and with the decrease in TPP addition level. The addition of chitosan and the replacement of native starch by hydrolyzed starch tend to increase storage stability of β-carotene encapsulated in the starch matrix because chitosan can act as a good film-forming and antioxidant, while hydrolyzed starch contains amylose amylopectin with a short chain which is better in film-forming ability. These results promote the use of the hydrolyzed starch-chitosan/TPP as a matrix to enhance the stability β-carotene via encapsulations.

A study of alginate-chitosan membrane synthesize was done. The membrane was prepared by mixing alginate hydrosol and chitosan hydrosol at mass ratio of 1:1 and pH of 5.28 approximately. Then it was applied for matrix immobilization of urease and bromothymol blue (BTB) by entrapment technique. The physical, chemical, thermal properties of alginate–chitosan membrane and their impact on immobilized urease activity were investigated. The polymer products were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). It’s showed that alginate-chitosan membrane was formed by electrostatic interaction. The obtained membran has better mechanical properties than original alginat and chitosan membranes. The immobilization urease into alginate-chitosan membrane retained the catalytic activity of the enzyme, as confirmed by color change of BTB indicator after membrane was immersed in substrate solution (urea). Therefore, alginate-chitosan membrane has good characteristics as matrix of enzyme immobilization.

Four chalcone derivatives were synthesized and pre-evaluated as broad-spectrum UV protector. Chalcones 1-4 showed a wide range of UV absorbance values and moderate molar absorptivity values. Chalcones 3 and 4 showed better photostability than chalcones 1 and 2 because the lowering of their absorbance was smaller and slower under UVB irradiation. A combination of the spectra of chalcone derivatives 1-4 indicated that a formulation containing all four will provide a broad-spectrum sunscreen protecting the skin from UVA and UVB.

PEC of the alginate-chitosan membrane as supporting material for immobilizing urease was produced. This study aimed to develop a supporting material for enzyme immobilization that has high stability, a fast response time and an easy and relatively inexpensive preparation procedure. An alginate-chitosan PEC membrane was produced by reacting alginate hydrosol and chitosan (1:1 in mass) at pH 5.28, followed by mixing and drying at room temperature. The FTIR spectra, XRD patterns and SEM assay confirmed that alginate-chitosan PEC was obtained. The color change of the BTB indicator proved that urease was trapped in the cavities of the alginate-chitosan PEC membrane while the immobilized urease still showed catalytic activity. Thus, the membrane of alginate-chitosan PEC has good characteristics as a matrix for urease immobilization.

To prevent an environmental pollution by hazardous heavy metals, in the present study, a simulatenous decrease of the concentration of Pb((II) and Cu(II) in the solution by photo-Fenton method has been systematically studied. Photo-Fenton process proceeded in a close reactor by batch technique. The process was conducted by exposure solutions containing Pb(II) and Cu(II) ions, and Fenton’s reagent (Fe2+ and H2O2) under UV-A lamp. In this study, the initial concentations of Pb(II) and Cu(II), and the exposure time were optimized. The synergyc effect that may be appeared on the decrease of Pb(II) and Cu(II) ion concentrations simultaneously through photo-Fenton process was also addressed. The concentrations of Pb(II) and Cu(II) in the solution were determined by AAS. The research results exhibited that photo-Fenton process could decrease Pb(II) and Cu(II) concentrations, and the maximum decreases, 46.12 % dan 16.86% for Pb(II) and for Cu(II) respecticely, were found by applying both initial concentration of Pb(II) and Cu(II) as much 35 mg/L, and 60 min of the time. The concentration decreases of Pb (II) and Cu(II) were results of oxidation by OH and by electron to form PbO2 and Cu particles respectively as probed by EDX data. Furthermore, photo-Fenton process toward a solution containing Pb(II) and Cu(II) ions allowed oxidation of Pb(II) and reduction of Cu(II) simultaneously and showed a synergic effect. Such effect was demonstrated by the fact that the presence of Cu(II) ion in the photo-Fenton process of Pb(II) solution could improve the Pb(II) oxidation and the highest improvement of Pb(II) oxidation (81.06%) was shown by 35 mg/L of the Cu(II) concentration. Similarly, the presence of Pb(II) in the photo-Fenton process of Cu(II) solution could enhance the reduction of Cu(II), and the highest effect on the Cu(II) reduction enhancement was exhibited by 35 mg/L of the Pb(II) concentration.

The preparation of polyelectrolyte complex (PEC) as supporting material of urease immobilisation for Hg(II) biosensor has done. PEC membrane can be prepared by mixing hydrosol alginate and chitosan hydrosol with 1: 1 ratio at pH of 5.28 approximately. The optimum conditions and characteristics of biosensor was determined. The formed alginate–chitosan PEC membrane was confirmed by using FTIR spectroscopy and SEM analysis. The results shoed that PEC of alginate-chitosan was formed and the proposed biosensor is an excellent platform for sensitive detection of Hg (II).

An amperometric biosensor for the indirect determination of Hg(II) has been developed based on inhibition of urease (EC 3.5.1.5) immobilized into alginate–chitosan polyelectrolyte complexes membrane. The biosensor response was monitored by following the reduction peak of hydrolyzed urea at around -0.15 V. The amperometric biosensor has a dynamic range 40–90 ppb Hg(II) with limit of detection of 66.45 ppb toward Hg(II) ions, repeatability (CV) value of 0.86% and only Ag(I) as the main potential interference. The sensor shows a stable and reproducible response for more than 2 weeks when it stored dry at 4 °C. The analytical results of Hg(II)-spiked water sample showed a good agreement with those obtained by atomic absorption spectrometry method, suggesting that the developed method may be applied in the determination of Hg(II) in the water samples.

Indonesia is rich with essential oils such as anise and clove leave oils. In respect to explore the potential utilization of these resources, it has been conducted the transformation of p-hydroxybenzaldehyde and vanillin (4-hydroxy-3-methoxy benzaldehyde) respectively derived from anise oil and clove leaves oil to a series of C-arylcalix[4]resorcinarenes and C-arylcalix[4]pyrogallolarene macrocycles. Treatment of these aldehydes with resorcinol in the presence of HCl in absolute ethanol at reflux for 8 h afforded C-4-hydroxyphenylcalix[4]resorcinarene (3a) and C-4-hydroxy-3-methoxy phenyl-calix[4]resorcinarene (3b) in good yields. When the aldehydes were treated with pyrogallol under the similar condition, the products were C-4-hydroxyphenyl calix[4]pyrogallolarene (3c) and C-4-hydroxy-3-methoxyphenylcalix[4]pyrogallolarene (3d) which were also obtained in excellent yields. Treatment of these calix[4]resorcinarenes and calix[4]pyrogallolarenes with cinnamoyl chloride and benzoyl chloride in pyridine afforded the corresponding cinnamate esters and benzoate esters in high yields. The resulted C-arylcalix-[4]resorcinarenes and C-arylcalix[4]pyrogallol arenes were subjected to antioxidant activity test using DPPH method and showed strong activity with IC50 values of 15–80 μg/mL. In terms of the synthesized calix cinnamates, the compounds showed UV-B absorption with SPF values of 15–30 at a concentration of 25 ppm which demonstrate their potential to be applied as a UV-B protector. Furthermore, these compounds were also tested for their photostability on the UV-B region and the results showed that the compounds were still unstable under irradiation for 30 min.

Magnetite-functionalized horse dung humic acid (HDHA) has been successfully prepared by the coprecipitation method, and the as-prepared adsorbent (MHDHA) has been applied as an easy-handling adsorbent for toxic Pb(II) in artificial wastewater. The MHDHA was characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), and vibrating sample magnetometer (VSM). The FT-IR study showed that the MHDHA had the characteristics peaks of HA and Fe-O stretching. The XRD analysis revealed that the MHDHA had the 2θ characteristic for magnetite. The TEM image and EDX analysis exhibited that the MHDHA with an average size of ∼14 nm was partially aggregated and contained (w/w) 9.89% carbon, 2.89% nitrogen, and 32.74% oxygen based on functional groups of HDHA. The stability improvement of MHDHA was showed by decreasing HDHA dissolved from 95% to less than 30% at pH 12 after magnetite functionalization. The post-adsorption handling improvement was evidenced by easy and quick retraction by an external magnet with a 62.95 emu/g magnetic strength value. The adsorption capacities were influenced by the pH and ionic strength, whilst the adsorption rates were well simulated by the Ho pseudo-second-order model. The removal uptake of Pb(II) ions increased when the initial concentration was increased and fitted well with the Langmuir isotherm model when the monolayer adsorption capacity was 2.78×10−4 mol/g (equal to 57.64 mg/g). The value of Dubinin-Radushkevich adsorption energy (ED−R) found in this study was 14.78 kJ/mol, which implied that ion exchange is the main mechanism involved in the adsorption process. The regeneration studies of MHDHA show that there was no significant change in composition, morphology, crystallinity, and functional group after five consecutive cycles of the adsorption-desorption process.

Synthesis of alginate-chitosan polyelectrolyte membrane and the determination of the physical-mechanical properties were carried out. Alginate-chitosan polyelectrolyte complex membrane can be made by mixing hydrosol alginate and chitosan hydrosol with a ratio of 1: 1 at pH 5.28. Membranes of alginate-chitosan polyelectrolyte complexes produced have physical-mechanical properties including load, elongation and elasticity, water absorption and resistance better than the constituent polymers. The results of FTIR spectroscopy analysis showed that there was an electrostatic interaction between alginate and chitosan through protonated amine groups of chitosan and carboxylic groups from alginate. Surface analyses by SEM showed that morphology of alginate-chitosan polyelectrolyte complex membrane was different with single membrane morphology

A synthesis and kinetic study of the urea controlled-release composite material based on isolated Na-lignosulfonate, Na-alginate and tapioca was carried out. This experiment’s aims were to isolate Na-lignosulfonate from wood sawdust and to applicate this isolated Na-lignosulfonate, along with tapioca and Na-alginate as urea control release composite material. A kinetic study of urea released from the composite materials was also conducted. Na-lignosulfonate was isolated by Kraft lignin method to give a brown solid yield of 16.92% and was characterized by FT-IR spectrophotometer and SEM-EDX. The composite materials were synthesized by blending urea as the active compound with composite material as the carrier compound. Three types of material were prepared: complete material (A), low-concentration Na-lignosulfonate material (B) and material without tapioca (C). The composite material had a spherical form with 0.79 mm radius and 2.16 mm swollen radius. Urea content inside material was 40.425 mg urea/g material. The urea diffusivity coefficient for material A, B, and C were 7.27 x 10–6; 15.50 x 10–6 and 0.94 x 10–6 m2 h–1, respectively. Modelling analysis showed the experiment obeyed around only 15% of the Korsmeyer–Peppas model, but there was good correlation (80%) with the unsteady-state diffusion model.

A study of eugenol release and its kinetics model from chitosan-alginate polyelectrolyte complex (PEC) films has been conducted. Some factors that affected the eugenol release were also studied, including the composition of chitosan-alginate PEC and the concentration of eugenol. The chitosan-alginate-eugenol PEC films were synthesized at pH ± 4.0, then the PEC films were characterized using a Fourier-transform infrared spectroscopy (FTIR) spectrophotometer. An investigation of the films’ properties was also conducted, including morphology analysis using a scanning electron microscope (SEM), differential thermal analysis (DTA) / thermogravimetric analysis (TGA), mechanical strength, transparency testing, water absorption, and water vapor permeability. The release of eugenol was investigated through in vitro assay in ethanol 96% (v/v) for four days, and the concentration of eugenol was measured using an ultraviolet-visible (UV-Vis) spectrophotometer. The characterization of the films using FTIR showed that the formation of PEC occurred through ionic interaction between the amine groups (–NH3+)of the chitosan and the carboxylate groups (–COO–) of the alginate. The result showed that the composition of chitosan-alginate PEC and the concentration of eugenol can affect the release of eugenol from PEC films. A higher concentration of alginate and eugenol could increase the concentration of eugenol that was released from the films. The mechanism for the release of eugenol from chitosan-alginate PEC films followed the Korsmeyer-Peppas model with an n value of < 0.5, which means the release mechanism for eugenol was controlled by a Fickian diffusion process. The antioxidant activity assay of the films using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method resulted in a high radical scavenging activity (RSA) value of 55.99% in four days.

An electronic tongue (e-tongue) based on an array of lipid/polymer membranes has been successfully developed for measuring the taste evolution of natural milk. The e-tongue consisted of 16 different lipid/polymer membranes combined with or without a pH sensor. The natural milk of bovine and goat were purchased from the local farming store in Malang-Indonesia. The taste measurement was carried out, from fresh (0 h) to stale (12 h), every two hours under room ambient without any treatment. The responses of the e-tongue were evaluated using a Principal Component Analysis (PCA) and a Linear Discriminant Analysis (LDA). From PCA results, the taste of both milk samples tends to change by time although some groups show a partial overlapping. LDA results show the high precision of the e-tongue in clustering taste evolution. The correctly classified groups after the cross-validation procedure were achieved 95.7 and 87.1% for bovine and goat milk, respectively. The improvement of the classification using LDA was obtained by adding data from a pH sensor of each measurement as 100 and 98.6% for bovine and goat milk, respectively. This work indicates that the lab-made e-tongue may be useful to predict the quality of natural milk for the food industry.

A study on the adsorption characteristic of Iron onto Poly[eugenol-co-(divinyl benzene)] (EDVB) from aqueous solution has been conducted. EDVB was produced and characterized by using FTIR spectroscopy. The adsorption was studied by a batch method by considering the factors affecting the adsorption such as initial metal ion concentration, adsorption selectivity, and mechanism of adsorption using a sequential desorption method. The adsorption of Iron onto EDVB followed a pseudo-2 order kinetics model with the rate constant of 0,144 L2 mmol-1 min-1. The adsorption isotherm was studied with Tempkin, Langmuir and Freundlich models. The adsorption capacity (Qmax) obtained by Langmuir isotherms was 250mg.L-1 while the equilibrium value was 0.8 Lmg-1. A competitive adsorption study showed that EDVB is adsorbed selectively towards Iron rather than Chromium, Coppers and Cadmium ions. The interaction type of Iron onto EDVB was determined by a sequential desorption. Keywords: Polyeugenol; divinyl benzene (DVB); adsorption; Iron; Fe References • Abasi, C. Y.; Abia, A.A.; Igwe, J.C. Adsorption of Iron (III), Lead (II) and Cadmium (II) Ions by Unmodified Raphia Palm (Raphia hookeri) Fruit Endocarp. Environ. Res. 2011, 5 (3), 104-113, ISSN: 1994-5396, Medwell Journals. DOI: 10.3923/erj.2011.104.113 • Baes, F. C.; Mesmer, R. E. The Hydrolisis of Cations; John Wiley: New York, 1976 • Bakatula, E.N.; Cukrowska, E.M.; Weiersbye, L.; Mihali-Cozmuta, L.;Tutu, H. Removal of toxic elements from aqueous solution using bentonite modified with L-histidine. Water Sci. Technol.2014, 70 (12),2022-2030, DOI: 10.2166/wst.2014.450 • Bhattacharyya, K.G.; Gupta, S.S. Adsorption of Fe(III) from Water by Natural and Acid Activated Clays: Studies on equilibrium isotherm, kinetics and thermodynamics of interactions. Adsorption. 2006, 12 (3), 185-204,DOI : 10.1007/s10450-006-0145-0 • Carmona, M..; Lucas, A.D.; Valverde, J.L.; Velasco, B.; Rodriguez, J.F. Combined adsorption and ion exchange equilibrium of phenol on Amberlite IRA-420.Chem. Eng. J.2006, 117, 155-160, Doi : 10.1016/j.cej.2005.12.013 • Debnath, S.; Ghosh, U.C. Kinetics, isotherm and thermodynamics for Cr(III) and Cr(VI) adsorption from aqueous solutions by crystalline hydrous titanium oxide. J. Chem. Thermodin. 2008, 40: 67-77, DOI: 10.1016/j.jct.2007.05.014 • Djunaidi, M.C.; Jumina; Siswanta, D.; Ulbricht, M. Selective Transport of Fe(III) Using Polyeugenol as Functional Polymer with Ionic Imprinted Polymer Membrane Method. Asian J. Chem. 2015, 27 (12): 4553-4562, DOI : 10.14233/ajchem.2015.19228 • Febriasari, A.; Siswanta, D.; Kiswandono, A.A.; Aprilita, N.H. Evaluation of Phenol Transport Using Polymer Inclusion Membrane (PIM) with Polyeugenol as a Carrier. Jurnal Rekayasa Kimia dan Lingkungan. 2016, Vol. 11, No. 2, 99-106, DOI: 10.23955/rkl.v11i2.5112 • Foldesova, M.; Dillinger, P.; Luckac, P. Sorption and Desorption of Fe(III) on Natural and chemically modified zeolite. J. Radioanal. Nucl. Chem. 1999, Vol. 242, No. 1 (1999), 227-230, DOI: 10.1007/BF02345926 • Gupta, V.K.;Sharma, S. Removal of cadmium and zinc from aqueous solutions using mud.Environ. Sci. Technol. 2002, 36: 3612-3617, DOI: 10.1021/es020010v • Handayani, D.S. Sintesis kopoli(eugenol-DVB) sulfonat dari Eugenol Komponen Utama Minyak Cengkeh Szygium aromaticum (Synthesis of copoly(eugenol-DVB) sulfonic from main components of eugenol clove oil Szygium aromaticum). Biopharmacy Journal of Pharmacological and Biological Sciences. 2004, 2 (2): 53-57 ISSN: 1693-2242. url : https://eprints.uns.ac.id/id/eprint/856 • Harimu, L.; Matsjeh, S.; Siswanta, D.; Santosa, S.J. Synthesis of Polyeugenyl Oxyacetic Acid as Carrier to Separate Heavy Metal Ion Fe(III), Cr(III), Cu(II), Ni(II), Co(II), and Pb(II) that Using Solvent Extraction Mehod. Indo. J. Chem. 2009, 9 (2): 261-266. • Ho, Y.S.; McKay, G. Pseudo-second Order Model for Sorption Processes. Process. Biochem. 1999, 34, 451-465, DOI: 10.1016/S0032-9592(98)00112-5 • Ho, Y.S.; McKay, G.; Wase, D.A.J.;Forster, C.F. Study of Sorption Divalent Metal Ions on to Peat. Adsorpt. Sci. Technol. 2000, 18: 639-650. DOI : 10.1260/0263617001493693 • Indah, S.; Helard, D.;Sasmita, A. Utilization of maize husk (Zea mays L.) as low-cost adsorbent in removal of iron from aqueous solution. Water Sci. Technol. 2016, 73 (12), 2929-2935, DOI: 10.2166/wst.2016.154 • Kiswandono, A.A.; Siswanta, D.; Aprilita, N.H.; Santosa, S.J. Transport of Phenol through inclusion polymer membrane (PIM) using copoly(Eugenol-DVB) as membrane carries. Indo .J. Chem. 2012, 12 (2): 105-112. Doi : 10.22146/ijc.667 • Kousalya, N.; Gandhi, M.R.; Sundaram, C.S.; Meenakshi, S. Synthesis of nano-hydroxyapatite chitin/chitosan hybrid bio-composites for the removal of Fe(III).Carbohyd. Polym. 2010, 82: 594-599, DOI:10.1016/j.carbpol.2010.05.013 • Kumar, K.V.; Porkodi, K.;Rocha, F. Langmuir-Hinshelwood kinetics – A theoretical study, Catalysis Communications. 2008, 9: 82-84, DOI:10.1016/j.catcom.2007.05.019 • Masel, R.I. Principles Adsorption and Reaction on Solid Surface; John Wiley & Sons: Canada, 1996 • Moore, J. W.; Pearson, R.G. Kinetics and Mechanism Third Edition; John Wiley & Sons: Canada, 1981. • Ngah, W.S.W.; Ghani, S.A.; Kamari, A. Adsorption Behaviour of Fe(II) and Fe(III) Ions in Aqueous Solution on Chitosan and Cross-linked Chitosan Beads. Bioresource. Technol. 2005, 96: 443-450. DOI:10.1016/j.biortech.2004.05.022 • Rahim, E.A.; Sanda, F.; Masuda, T. Synthesis and Properties of Novel Eugenol-Based Polymers. Polymer Bulletin. 2004, Vol. 5, 93-100, DOI: 10.1007/s00289-004-0272-2 • Samarghandi, M.R.; Hadi. M.; Moayedi, M.; Askari, F.B. 2009. Two Parameter Isotherms of Methyl Orange Sorption by Pinecone Derived Activated Carbon. Iran. J. Environ. Health Sci. Eng., 6 (4): 285-294. • Setyowati, L. 1998. Pengaruh Penambahan Divinil Benzena (DVB) pada Kopolimerisasi Kationik Poli[eugenol-co-(divinil benzena)] dan Sifat Pertukaran Kation Kopoligaramnya (The Effect of divinylbenzene (DVB) Addition to Eugenol-DVB Cationic Copolymerization and Its Use As Cation-Exchanger), Thesis, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta, Indonesia. • Shi, T.; Jia, S.; Chen, Y.; Wen, Y.; Du, C.; Guo, H.; Wang, Z. Adsorption of Pb(II), Cr(III), Cu(II), Cd(II) and Ni(II) onto a vanadium mine tailing from aqueous solution. J. Hazard. Mater. 2009, 169: 838-846, DOI: 10.1016/j.jhazmat.2009.04.020 • Sun, S.;Wang, A. Adsorption Kinetics of Cu(II) Ions Using N,O-Carboxymethyl-Chitosan. J. Hazard. Mater. 2006, B131: 103-111, DOI: 10.1016/j.jhazmat.2005.09.012 • Sun, S.; Wang, L.;Wang, A. Adsorption Properties of Crosslinked Carboxymethyl-chitosan Resin With Pb(II) as Template Ions. J. Hazard. Mater. 2006, B136: 930-937, DOI: 10.1016/j.jhazmat.2006.01.033 • Uzun, I.; Guzel, F. Adsorption of Some Heavy Metal Ions from Aqueous Solution by Activated Carbon and Comparison of Percent Adsorption Result of Activated Carbon with those of Some Other Adsorbents. Turk. J. Chem. 2000, 24: 291-297. • Zou, X.; Pan, J.; Ou, H.; Wang, X.;Guan, W.; Li, C.; Yan, Y.; Duan, Y. Adsorptive removal of Cr(III) and Fe(III) from aqueous solution by chitosan/attapulgite composites: Equilibrium, thermodynamics and kinetics. Chem. Eng. J. 2011, 167: 112-121, DOI: 10.1016/j.cej.2010.12.009

The coating Fe3O4 using humic acid (HA) to form HA-coated Fe3O4 (Fe3O4/HA) was conducted and applied for phenol sorption. Fe3O4/HA was prepared using co-precipitation method in an alkaline condition using ammonium hydroxide and the addition of HA with mass ratios of Fe3O4 and HA=20:1, 10:1, 10:2, 10:3. The HA from peat soil in Sambutan village, East Kalimantan, Indonesia and was extracted in NaOH 0.1 M solution. The FT-IR characterization indicated that the coating of HA on the surface of Fe3O4 was successfully synthesized by forming a bond between the carboxylate group of HA and iron of Fe3O4. The coating of HA on the surface of Fe3O4 did not change the crystal structure of Fe3O4, but had lower peak intensities than Fe3O4 if added with HA with mass ratios 20:1, 10:1, 10:2, 10:3. The saturation magnetization of Fe3O4 decreased with the increased content of HA. SEM image indicated the magnetic particle size was almost homogenous by 10-18 nm. Iron and HA in Fe3O4/HA materials synthesized using different mass ratios were stable in pH range of 3.0-11.0 and 1.0–11.0, respectively. The phenol sorption on Fe3O4 was optimum at pH 5.0 and on Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3 were optimum at pH 5.0-6.0. The kinetics model for phenol adsorption on Fe3O4 and Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3 could be described using pseudo second-order equation and was in accordance with the Langmuir isotherm model with maximum adsorption capacity of 0.45 mmol/g for Fe3O4 and 0.55, 0.56, 0.58, 0.56 mmol/g respectively for Fe3O4/HA with mass ratios of 20:1, 10:1, 10:2, 10:3. The adsorption capacity increased with the increased content of HA, but the adsorption energy decreased except Fe3O4/HA with a mass ratio of 10:3. Generally, the performance of Fe3O4/HA materials was much higher than of bare Fe3O4.

A simple, cheap and environmentally friendly analytical method of Cd(II) in the aqueous system has been developed by immobilization of 1-(2-pyridilazo)-2-naphtol (PAN) in poly vinyl chloride (PVC) matrix and nitrophenyl octyl ether (NPOE) as a plasticizer. Upon contact with Cd(II) in solution, the color of sensor membrane changes from dark yellow to dark red, which is due to the formation of Cd(II)–PAN complex. The best sensing results were obtained at pH 8.0 and λmax 558 nm. The dimension of the proposed sensor membrane was 0.8 cm x 2 cm with a thickness of 0.05 mm, the volume of sample was 2 mL with the Cd(II) concentration range of 0 – 1.2 ppm. The limit of detection of the method was found to be 0.432 + 0.104 ppm, which was reversible. The proposed methods have been applied in the determination of Cd(II) in water samples after addition of internal standard.

Humic acid (HA) extracted from peat soil according to the recommended procedure of the International Humic Substances Society (IHSS) has been tested to remove AuCl4- from aqueous solution. The removal was optimum at pH 2.0 and it was mainly dictated by attachment through hydrogen bonding to unionized carboxyl (–COOH) groups and reduction by the action of the hydroxyl (–OH) groups to gold (Au) metal. The removal of AuCl4- improved after HA was purified through repeated immersion and shaking in a mixed solution containing 0.1 M HCl and 0.3 M HF. When the purification led to the sharp decrease in ash content from 39.34 to 0.85% (w/w) and significant increase in both the –COOH and –OH contents from 3240 to 3487 mmol/kg and from 4260 to 4620 mmol/kg, respectively; the removal of AuCl4- improved from 0.105 to 0.133 mmol/g. This improvement of AuCl4- removal by the purified HA was accompanied by higher ability in reduction to Au metal. The attached AuCl4- on –COOH groups of both crude and purified HAs was qualitatively observed by the characterization result of FT-IR spectroscopy, while the presence of Au metal on the surface of those HAs was verified by the characterization result of XRD.

It has been examined the application of Mg/Al-NO3 hydrotalcite-magnetite synthesized mechanically (MHT) and ultrasonically (UMHT) by co-precipitation method as adsorbents for [AuCl4]– from aqueous solution. Two techniques of synthesis were conducted to determine the effect on the increase of adsorption ability of the [AuCl4]–. Magnetite and Mg/Al-NO3 hydrotalcite-magnetite synthesized by co-precipitation with modifications hydrothermal treatment at 120 °C for 5 h. The adsorbents were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and Vibrating sample magnetometer (VSM). Adsorption studies were done by getting the optimum pH, optimum contact time and the optimum concentration. A result of the adsorption study of [AuCl4]– on both adsorbents was optimum at pH 3 and fitted well to Langmuir isotherm and pseudo second-order kinetic models. The adsorption capacity of UMHT (ultrasonic technique) was 66.67 mg g-1 and it was higher than that of MHT (mechanic technique), i.e. 31.25 mg g-1. This shows that the ultrasonic radiation technique can increase the adsorption capacity of the [AuCl4]–. Based on the desorption using 0.5 mol L-1 NaOH solution, more [AuCl4]– was eluted from MHT, indicating that [AuCl4]– was weakly bound on MHT than UMHT.

A recovery study of phenol with Polymer Inclusion Membranes (PIMs) needs to be evaluated to determine values of transport kinetic parameter, level of stability, and selectivity of the membrane. This paper describes results of the evaluation of phenol transport using PIMs with polyeugenol as a carrier. PIMs were made by mixing polyeugenol, dibenzylether, and polyvinylchloride in a solvent (tetrahydrofuran) then printed in a container with diameter 4.5 cm and allowed to vaporize for 72 hours. Further evaluation studies are conducted at pH 4.5 with various parameters, among of them are various times that were taken to identify parameters of the transport kinetics of phenol, membrane stability, characterization, and testing of membrane selectivity by comparing transport of phenol with another compound, in this study chromium is used. This study results in calculation of values of transport kinetics of membrane permeability obtained at 8.8 x 10-5 m/s, flux value of 9.512 x 10-4 g/m2s, and diffusion coefficient of 3.826 x 10-11 m2/s. Repeating use over three times, 48 hours, indicates reduction in power of phenol transport by 70.81%. While selectivity test indicates that membrane is used more selectively against phenol than chromium metal. Based on study results, phenol transport effectiveness using PIM with polyeugenol as carrier is 91.4% in optimum condition.

Preparation of membrane using crosslinking reaction between chitosan and citric acid showed that functional group modification increased the number of active carrier groups which lead to better transport capacity of the membrane. In addition, the substitution of the carboxyl group increased creatinine permeation of chitosan membrane. The transport capacity of citric acid crosslinked chitosan membrane for creatinine was found to be 6.3 mg/L. The presence of cyanocobalamin slightly hindered the transport of creatinine although compounds did not able to pass through citric acid crosslinked chitosan/poly(vinyl alcohol) blend membrane, as compounds no found in the acceptor phase.

QSAR studies had done on derivatives of triazolopiperazine amide as inhibitors DPP IV enzyme that causes diabetes mellitus type 2. The studies had began by modeling the structures of the derivatives of triazolopiperazine amide and calcutating the descriptors of QSAR by semiempirical AM1 method which available on HyperchemÒprogram. QSAR analysis had done by multilinear regression method analysis which is available on SPSSÒprogram using electronic and molecular parameters. The best QSAR equation model for method of semiempirical AM1: -log IC50 = 152.252 + (18,.295*qC1) + (2.343*qC5) + (2263.448*qC9) + (1662.252*qC10) – (350.806*qC15) + (639.687*qO25)+ (6.515*EH) n = 18; r2 = 0.712; adjusted r2 = 0.510; Fhit/Ftab = 1.124; PRESS = 0.006 The main side of the compound can be determined through the equation. It can be used to study in preventing the disease of DM2 by inhibiting of enzyme DPP IV.

Fe-Ionic Imprinted Polymer (IIP) from polyeugenol as base polymer and polyethylene glycol diglycidyl ether (PEGDE) as cross-linking agent had been synthesized to adsorb Fe(III) from aqueous media. The non-imprinting material (NIP) and polyeugenol were used in the adsorption study as control. Synthesis work included polymerization, template uploading, crosslinking and template removal, optimized for different template ion upload pH and concentrations. The polymers were characterized by FTIR spectroscopy, XRD and SEM-EDX, followed by adsorption test to study the adsorption kinetics and isotherms for all adsorbents. Selective adsorption study of IIP was carried out using binary mixtures of Fe(III) and Cr(III), Pb(II), Cd(II). Experimental results showed that the optimum conditions for the synthesis was template upload pH of 3, Fe/polyeugenol ratio of 1 mg/g, while the optimum adsorption pH was 3. The adsorption mechanism of Fe(III) on all adsorbents was dominated by hydrogen bond formation. The adsorption kinetics followed the pseudo-second-order model while the equilibrium data was best explained by the Langmuir isotherm model. The adsorption capacity of Fe(III) on the IIP was 12.73 mg/g, higher than that of the other adsorbents. Results also show that IIP-Fe was more selective toward Fe than NIP by 2.69 (Cd), 1.66 (Cr) and 1.6 (Pb) fold, respectively.

A modified pectin has been synthesized by reacting/combining -OH group among pectin and chitosan with BADGE (Bisphenol A diglycidyl ether) crosslinker agent. The structure and morphology of the new material were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray Diffraction (XRD) analysis. Thermogravimetric studies showed an improvement in thermal characteristic. Adsorption experiments were performed in batch processes; sorption isotherms and kinetics were also studied. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Pb(II) ion onto adsorbent pectin-carboxymethyl chitosan-BADGE (pec-CMC-BADGE). The dynamic study showed that the sorption process followed the second-order kinetic equation. Result indicated also that Pb(II) ion uptake could be well described by the Langmuir and Freundlich adsorption model of pec-CMC-BADGE and CMC with DG° of 25.3 and 23.1 kJ mol-1,respectively, while that of pectin followed Freundlich isotherm with DG° of 16.6 kJ mol-1.

An ester of butanediol-alginate has been studied as a possible hemodialysis membrane. With 1,4-butanediol molar ratio of 0.1, 0.5, and 1.0, it showed that the membrane mechanical properties, stability, protein adsorption, platelet adhesion and performance for urea and creatinine clearance are better than that of unmodified alginate. The increase in 1,4-butanediol molar ratio causes hemodialysis ratio to improve, and causes protein adsorption and platelet adhesion at the membrane surface to decrease. In the case of protein adsorption and platelet adhesion, the membrane with the molar ratio of 1.0 has better hemocompatibility properties. In the hemodialysis test for 4 h, using 2.742 mg cm-2 h-1 of urea and 0.058 mg cm-2 h-1 of creatinine flux, this membrane showed that 48.5% of urea and 44.2% of creatinine were cleaned.

Penentun metode komputasi untuk analisis hubungan kuantitatif struktur dan aktivitas (HKSA) telah dilakukan pada senyawa turunan triazolopiperazin amida sebagai inhibitor enzim DPP IV yang merupakan penyebab diabetes melitus tipe 2 (DM2). Metode komputasi yang digunakan untuk analisis ini adalah metode semiempirik. Analisis dilakukan dengan pemodelan struktur senyawa turunan triazolopiperazin amida dan perhitungan deskriptor HKSA dilakukan menggunakan program Hyperchem. Parameter yang digunakan adalah pergeseran kimia 13C NMR, panjang ikatan antaratom, sudut ikatan antaratom, dan muatan atom bersih. Hasil perhitungan parameter tersebut dibandingkan dengan data empiris dan hasil perhitungan metode ab initio. Hasil penelitiannya menunjukkan bahwa metode semiempirik yang sesuai untuk analisis HKSA senyawa turunan triazolopiperazin amida adalah AM1 dan PM3.

Immobilization of humic acid on chitin has been conducted and applied to the adsorption of Cr(III). The humic acid was isolated using NaOH 0.1 M, while chitin was isolated by deproteination of crab shells by using NaOH 3.5 % (w/v) and followed by demineralization using HCl 1 M. Chitin obtained from ambient-temperature-dried crab shell is named as chitin I, and crab shell washed by HOCl solution and followed by drying at ambient temperature is named chitin II. The total acidity of the humic acid was 230.95 cmol/kg, and it was distributed into the acidity of COOH 168.75 cmol/kg, and phenolic-OH 62.20 cmol/kg. Adsorbent A with chitin I as the main material and adsorbent B with chitin II as the main material, resulted the adsorbed humic acid of 9.25 and 1.68% (w/w), respectively. Adsorption of Cr(III) was maximum at pH 5, with rate of constants orde of chitin II>adsorbent B>adsorbent A>chitin I, i.e. 0.3509; ; 0.2488; 0.1553; 0.0568 minute-1, respectively. The capacity of adsorption was in the orde of chitin I>adsorbent B>chitin II>adsorbent A, i.e. 944.77; 912.53; 895.37; 893.81 mg/g, respectively. The energy of adsorption of Cr(III) of chitin II>chitin I>adsorbent A>adsorbent B, i.e. 22.932; 20,945; 20.312; 19.615 kJ/mol, respectively.

The aims of this research is to synthesize Pb(II) imprinted polymers with carboxymethyl chitosan (CMC) as polymers and bisphenol A diglycidyl ether (BADGE) as cross-linker (Pb-IIP). Chitosan (CTS), non imprinted polymer (NIP) and Pb-IIP were characterized using infrared (IR) spectroscopy, X-ray diffraction (XRD), surface area analyzer (SAA), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. The result showed that the adsorption was optimum at pH 5 and contact time of 250 min. Adsorption of Pb(II) ion with all of adsorbents followed pseudo-second order kinetic equation. Adsorption of Pb(II) ion on CTS followed Freundlich isotherm while that on NIP and Pb-IIP followed the Langmuir adsorption isotherm. The adsorbent of Pb-IIP give higher capacity than the NIP and CTS. Adsorption capacity of Pb-IIP, NIP and CTS were 167.1, 128.9 and 76.1 mg/g, respectively. NIP gave higher adsorption selectivity for Pb(II)/Ni(II) and Pb(II)/Cu(II), whereas Pb-IIP showed higher adsorption selectivity for Pb(II)/Cd(II).The hydrogen bonding dominated interaction between Pb(II) ion on NIP and Pb-IIP.

The aims of this research is to synthesize a chitosan derivative insoluble in acidic aqueous medium and that has high adsorption capacity for Pb(II) ions by cross-linking and grafting. Cross-linking and grafting were done using ethylene glycol diglycidyl ether (EGDE) and chloroacetic acid, respectively. The modified chitosan was characterized using FTIR spectrophotometer, XRD and TG-DTA. Chitosan and Chit-EGDE-Acetate was applied as adsorbent of Pb(II) ions in a batch system. The concentration of Pb(II) in adsorption medium was quantified using AAS. The result showed that the adsorption was optimum at pH 5, contact time of 200 min for chitosan and 300 min for Chit-EGDE-Acetate. Adsorption of Pb(II) ions on both adsorbents followed pseudo second order kinetic equation. Adsorption of Pb(II) ions on chitosan followed Freundlich isotherm while that on Chit-EGDE-Acetate followed the Langmuir adsorption isotherm. The adsorption capacity of Chit-EGDE-Acetate for Pb(II) ions was 200.0 mg L-1 while that for chitosan was 166.7 mg L-1. Interaction type of Pb(II) ions on adsorbent was determined by sequential desorption.

This paper discusses the preparation, characterization, and the evaluation of adsorption properties of resin poly-tetra-p-allylcalix[4]arene tetra acetic acid from the p-t-butylphenol. The synthesized resins were applied as an adsorbent for Cr(III) and Pb(II) metal ions. The adsorption was conducted in a batch system by investigating the effects of acidity (pH), contact time and initial concentration of a heavy metal solution. The adsorption of Cr(III) and Pb(II) metal ions on the resin had the optimum pH rating in region of 4–6 and reached the equilibrium condition in 40 minutes. The adsorption of Cr(III) and Pb(II) metal ions on the resin follows the Langmuir isothermal pattern with the linearity constant (R2 ) of Cr(III) and Pb(II) adsorption, whose results were 0.9640 and 0.9716, respectively. The adsorption capacity of Cr(III) and Pb(II) metal ions is 323.0 µmole/g and 33.4 µmole/g, while the adsorption energy is 30.4 kJ/mole and 39.7 kJ/mole, respectively. Most parameters in batch systems confirm that resin is a good adsorbent for Cr(III) and Pb(II), though Cr(III) adsorption was more favorable than that of Pb(II). The outstanding adsorption abilities for Cr(III) and Pb(II) metal ions have exhibited good prospects for disposal application of polluted water and environmental protection.

The influence of cross-linking and membrane hydrophilicity on the transport rate had been studied using a membrane prepared from a mixture of chitosan/PVA cross-linked citric acid (PVA.cl.CA) for creatinine and urea transport. The optimum mole ratio of PVA:citric acid as well as the best composition of chitosan:PVA.cl.CA were determined using creatinine transport study. Using the optimum compositions, further study was done using different thickness of the membrane in transporting creatinine, urea and a mixture of 3 species (creatinine, urea and vitamin B12). Membrane characterization was done using FT-IR spectrophotometer, water absorption test, TG/DTG and SEM. The results showed that the optimum composition PVA:citric acid was obtained to be 90:1, having % WU of 113.74% and creatinine transport percentage of 18.16%. Meanwhile, the optimum composition of chitosan:PVA.cl.CA was found at 4:6 ratio having % WU and % transport of 136.67% and 24.26%, respectively. The optimum transport capacity was found for membrane thickness of 50 µm with WU% at 139.61% and the percent transport of creatinine and urea each was 38.93% and 60.36%. The presence vitamin B12 in the solution of is proved to disturb the transport of creatinine and urea through the membrane. Finally, hydrophilicity seemed to give substantial contribution in the transport process as well as the mechanical strength of the membrane.