A novel hydrogel was synthesized through the graft copolymerization of acrylic acid (AA) and acrylamide (AM) onto sodium alginate with ammonium persulfate as the initiator, methylene bisacrylamide as the crosslinking agent, and calcium chloride as the precipitating agent. Rapeseed meal biochar made at 300 °C was also used. A series of graft copolymers with various molar ratio of AA to AM was prepared. The structures of the hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The free absorbency and rate of release were investigated. The grafting efficiency increased as the concentration of AM increased. There was a considerable percentage of nitrogen in the graft copolymers, and the release rate of nitrogen from fertilizer in soil and water decreased with increasing concentration of AM. The water retention of soil without hydrogel remained at 63 and 53.4% on the 10th and 20th days, but with the hydrogels, it was above 70% even on the last day. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45966.

A novel organo-nanoclay, i.e., diclofenac modified montmorillonite was used as a green and selective support for the adsorption of Pd(II) ions from aqueous solution. The diclofenac-montmorillonite composite was prepared and characterized by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Batch experiments were carried out with an equilibrium time of 30 min and the kinetics models of the interaction were studied. The selectivity of the sorbent towards Pd(II) was extremely good at a pH of 6.0-7.0, while the adsorption of other cations was low. The adsorption data were measured at room temperature and the yielded Langmuir monolayer capacity was 20.0 mg g À1 . The adsorption reaction was exothermic and the thermodynamic parameters, DH, DS and DG, at room temperature were À34.37 kJ mol À1 , À116.56 J K À1 mol À1 , and +0.96 kJ mol À1 , respectively. The specific surface area increased from 35.8 m 2 g À1 to 80.6 m 2 g À1 for the modified clay, suggesting that intercalation creates a porous framework thereby increasing the surface area and increasing the selectivity of this sorbent for the adsorption of Pd(II) ions. In order to evaluate the applicability of this support for the uptake of palladium from complex matrices, different real samples such as: road dust, rice, urine and water samples were analyzed.

Application of treated sawdust with NaOH as a green and economical sorbent for simultaneous preconcentration of trace amounts of Cd(II), Co(II), and Pb(II) ions from liver, lettuce, fish, and water as test samples with complicated matrices was investigated. Various parameters, such as effect of pH and contact time, breakthrough volume, type, and concentration of eluent and interference of ions were studied. The sorption was quantitative in the pH of 5.0 to 7.0 and desorption occurred instantaneously with 5.0 mL of mixed solutions of ethanol and 2.0 mol/L HNO3 -HCl and the amount of ions was measured by using flame atomic absorption spectrometry. Linearity was maintained at 3 to 500 μg/L for cobalt, 5.0 to 800 μg/L for lead, and 2.0 to 300 μg/L for cadmium in the original solution. The relative standard deviation was less than 1.80% (n = 6, with concentration of 0.3 mg/L for cadmium and 0.5 mg/L for lead and cobalt). Detection limits and maximum capacity of the sorbent for Co (II), Cd (II), and Pb (II) in the original solution were 0.86, 0.50, and 1.7 μg/L and 28.5, 30.6, and 47.3 mg/g, respectively. The results for spiked real samples, effect of interfering ions, and adsorption capacity indicated that the applicability of this method for lead preconcentration is better than cadmium and cobalt preconcentration from complicated matrices. Practical Application: Sawdust can be applied as a green and economical sorbent for simultaneous preconcentration and solid-phase extraction of metal ions from food and environmental samples with complicated matrices.

A simple and relatively selective solid phase extraction system has been described and used for determination of trace amounts of Ni(II) ions in water, soil and split peas by sodium dodecyl sulfate (SDS)-coated microparticles of walnut sawdust modified with dimethylglyoxim. Scanning electron microscopy (SEM) and Fourier transformed infrared (FT-IR) techniques were used for characterization of the sorbent. Adsorption experiments were carried out using batch mode under various operating conditions. The effect of pH, contact time, ionic strength, volume and concentration of the eluent on the Ni(II) preconcentration were studied. The equilibrium time was found to be 30 min and the adsorbed ions were stripped from the solid phase by 10 mL of 3 mol L À1 nitric acid. The eluting solution was analyzed for the Ni(II) content by flame atomic absorption spectrometry (FAAS). The adsorption data were measured at room temperature and the yielded Langmuir monolayer capacity was 22.0 mg g À1 . The detection limit (LOD) and the relative standard deviation were 0.55 mg L À1 and 3.1% (n ¼ 5, concentration ¼ 0.1 mg L À1 ), respectively. The accuracy of the method was examined with the determination of nickel ions in a certified reference material (CRM TMDW-500, drinking water).