Md. Jelas Haron

Removal of Cu and Pb by tartaric acid modified rice husk from aqueous solutions

A study on the modification of rice husk by various carboxylic acids showed that tartaric acid modified rice husk (TARH) had the highest binding capacities for Cu and Pb. The carboxyl groups on the surface of the modified rice husk were primarily responsible for the sorption of metal ions. A series of batch experiments using TARH as the sorbent for the removal of Cu and Pb showed that the sorption process was pH dependent, rapid and exothermic. The sorption process conformed to the Langmuir isotherm with maximum sorption capacities of 29 and 108 mg/g at 27 +/- 2 degrees C for Cu and Pb, respectively. The uptake increased with agitation rate. Decrease in sorbent particle size led to an increase in the sorption of metal ions and this could be explained by an increase in surface area and hence binding sites. Metal uptake was reduced in the presence of competitive cations and chelators. The affinity of TARH for Pb is greater than Cu.

Synthesis, surface modification and characterisation of biocompatible magnetic iron oxide nanoparticles for biomedical applications.

Superparamagnetic iron oxide nanoparticles (MNPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. These applications required that the MNPs such as iron oxide Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) having high magnetization values and particle size smaller than 100 nm. This paper reports the experimental detail for preparation of monodisperse oleic acid (OA)-coated Fe3O4 MNPs by chemical co-precipitation method to determine the optimum pH, initial temperature and stirring speed in order to obtain the MNPs with small particle size and size distribution that is needed for biomedical applications. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). The results show that the particle size as well as the magnetization of the MNPs was very much dependent on pH, initial temperature of Fe2+ and Fe3+ solutions and steering speed. The monodisperse Fe3O4 MNPs coated with oleic acid with size of 7.8 ± 1.9 nm were successfully prepared at optimum pH 11, initial temperature of 45 °C and at stirring rate of 800 rpm. FTIR and XRD data reveal that the oleic acid molecules were adsorbed on the magnetic nanoparticles by chemisorption. Analyses of TEM show the oleic acid provided the Fe3O4 particles with better dispersibility. The synthesized Fe3O4 nanoparticles exhibited superparamagnetic behavior and the saturation magnetization of the Fe3O4 nanoparticles increased with the particle size.

Removal of Cu and Pb from electroplating wastewater using tartaric acid modified rice husk

The potential of using tartaric acid modified rice husk (TARH) as a sorbent for the removal of Cu and Pb from semiconductor electroplating wastewater was investigated. Application of Langmuir isotherm indicated that there was no difference in the sorption capacity of TARH for Cu and Pb in synthetic solution and wastewater. A series of column studies were carried out. Increase in column bed depth yielded longer service time while increase in influent concentration and flow rate resulted in faster breakthrough. The sorption capacities of the TARH column for Cu and Pb agreed closely with the levels obtained from batch equilibrium studies. Theoretical breakthrough curves at different bed heights and flow rates generated using a two-parameter model agreed closely with experimental values in the treatment of semiconductor wastewater. In the regeneration study, Cu and Pb could be recovered almost quantitatively by eluting the column with 0.1 M HCl and the column could be used repeatedly for at least five cycles.

Removal of arsenite and arsenate ions from aqueous solution by basic yttrium carbonate

A new method has been developed to remove arsenite and arsenate ions from aquatic systems by using basic yttrium carbonate (BYC). Various parameters such as pH, anion concentration and reaction time were studied to establish optimum conditions. The removal by adsorption of arsenite and arsenate ions was found to be > 99% depending on initial concentration in the pH range of 9.8–10.5 and 7.5–9.0, respectively. The arsenate was also removed by precipitation at pH lower than 6.5 due to dissolution of BYC. The kinetic study shows that the adsorption follows the first order reaction. The adsorption isotherms of these anions were also studied at different temperatures. The equilibrium data fit well in the Langmuir model of adsorption. The Langmuir constants were calculated at different temperatures and the adsorption capacity for both anions increases with temperature. Anions such as Cl−, Br−, I−, NO−3 and SO2−4 have no interference in the removal process. The mechanism of the removal by adsorption was interpreted in terms of the surface charge and ligand orientation of BYC. The method was applied on synthetic wastewaters. Arsenite was oxidized to arsenate by 3% hydrogen peroxide. The yttrium was regenerated as basic yttrium carbonate.

Removal of fluoride ions from aqueous solutions by multivalent metal compounds

The removal of fluoride ions by Al(III) ion, Ca(II) ion and solid compounds of multivalent metal elements such as Al(III), Y(III), La(III), Ce(III), Nd(III), Sm(III), Gd(III), Si(IV), Ti(IV), Zr(IV) and Ce(IV) in the form of oxides, hydrous oxides and basic carbonates is studied. With an excess amount (20 mM) of Ca or Al ion, fluoride was removed from 5.0 to < 0.02 mM by precipitation (pH 4‐) and coprecipitation (pH 5.5–7.5), respectively. With a small dose, the solid trivalent metal compounds were effective in decreasing the fluoride concentration to < 0.02 mM below a certain pH. The dissolution of the material became appreciable at a pH where the lowest fluoride concentration was attained. Among the tetravalent metal compounds, only hydrous cerium(IV) oxide was effective in removing fluoride ions without a significant dissolution even at pH 2. It is suggested that fluoride ions are removed mainly by an ion exchange process with surface hydroxide groups in a neutral pH range, but by both ion exchange and...

Sorption of arsenate and arsenate anions by iron(III)-poly(hydroxamic acid) complex

Iron(III)-poly(hydroxamic acid) resin complex has been studied for its sorption abilities with respect to arsenate and arsenite anions from an aqueous solution. The complex was found effective in removing the arsenate anion in the pH range of 2.0 to 5.5. The maximum sorption capacity was found to be 1.15 mmol/g. The sorption selectivity showed that arsenate sorption was not affected by chloride, nitrate and sulphate. The resin was tested and found effective for removal of arsenic ions from industrial wastewater samples.

Synthesis and characterization of poly(hydroxamic acid) chelating resin from poly(methyl acrylate)-grafted sago starch

A new chelating ion-exchange resin containing the hydroxamic acid functional group was synthesized from poly(methyl acrylate) (PMA)-grafted sago starch. The PMA grafted copolymer was obtained by a free-radical initiating process in which ceric ammonium nitrate was used as an initiator. Conversion of the ester groups of the PMA-grafted copolymer into hydroxamic acid was carried out by treatment of an ester with hydroxylamine in an alkaline solution. The characterization of the poly(hydroxamic acid) chelating resin was performed by FTIR spectroscopy, TG, and DSC analyses. The hydroxamic acid functional group was identified by infrared spectroscopy. The chelating behavior of the prepared resin toward some metal ions was investigated using a batch technique. The binding capacities of copper, iron, chromium, and nickel were excellent and the copper capacity was maximum (3.46 mmol g−1) at pH 6. The rate of exchange of the copper ion was very fast that is, t1/2 Fe3+ > Cr3+ > Ni2+ > Co2+ > Zn2+ > Cd2+ > As3+ > Pb2+.

Sorption of fluoride ions from aqueous solutions by a yttrium‐loaded poly(hydroxamic acid) resin

Yttrium‐loaded poly(hydroxamic acid) ion‐exchange resin (YPHA) has been studied to sorb fluoride ion from aqueous solutions. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.002 mM in the pH range of 2.8 to 4.2. The rate constant for the sorption was found to be 5.6 x 10‐2 min‐1. The sorption of the fluoride was the Langmuir type and its capacity was 0.68 mmol‐F/g resin. The sorption selectivity shows that the fluoride removal may be interfered by the presence of phosphate and sulphate but was not affected by chloride, bromide, iodide and nitrate ions. The removal of fluoride from actual industrial wastewaters was more than 96%. A column test shows that fluoride ion was retained on the column until the breakthrough point. The fluoride ion sorbed can be eluted from the resin with 100 mM sodium hydroxide, and the column can be reused after being conditioned with 1 mM hydrochloric acid.

REMOVAL OF FLUORIDE ION FROM AQUEOUS SOLUTION BY A CERIUM-POLY(HYDROXAMIC ACID) RESIN COMPLEX

A cerium-loaded poly(hydroxamic acid) chelating ion exchanger was used for fluoride ion removal from aqueous solution. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.001 mM in acidic pH between 3 and 6. The sorption followed a Langmuir model with a maximum capacity of 0.5 mmol/g. The removal is accomplished by an anion exchange mechanism. The rate constant for the sorption was found to be 9.6 × 10−2 min−1. A column test shows that the fluoride ion was retained on the column until breakthrough point and the fluoride sorbed in the column can be eluted with 0.1 M NaOH. The column can be reused after being condition with hydrochloric acid at pH 4. The resin was tested and found to be effective for removal of fluoride from actual industrial wastewater.

Synthesis and properties of poly(hydroxamic acid) from crosslinked poly(methacrylate)

Poly(hydroxamic acid) chelating ion-exchange resin was prepared from crosslinked poly(methacrylate) beads. The starting polymer was prepared by a suspension polymerization of methacrylate and divinyl benzene. Conversion of the ester groups into the hydroxamic acid was carried out by treatment with hydroxylamine in an alkaline solution. Hydroxamic acid capacity of the product was 2.71 mmol/g. The resin exhibited high affinity towards Fe(III) and Pb ions and its capacities for Fe(III), Pb, Cu, Ni and Co ions were pH dependent. The ability of the resin to carry out the separation of Fe(III)CuCo/Ni and PbNi ions is also reported.