Sazmal E. Arshad

Synthesis and Characterization of Ethyl Cellulose–Based Liquid Crystals Containing Azobenzene Chromophores

Two compounds based on the ethyl cellulose having azobenzene side chain mesogenic units were prepared and the structures of the cellulosic liquid crystals were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectra. Liquid-crystalline properties were characterized by differential scanning calorimetry and polarizing optical microscopy in which compound 4a shows a columnar phase and compound 4b shows a semectic A phase. The absorption spectra of the azobenzene units display a high-intensity π–π* transition at about 364 and 366 nm for compounds 4a and 4b, respectively, and a lower intensity n–π* transition at around 468 nm for both compounds. Hence, photochromism can be achieved by the introduction of the azo linkage to ethyl cellulose containing liquid crystals.

Synthesis of ion imprinted polymers for selective recognition and separation of rare earth metals

Lanthanide-ion imprinted polymers (L-IIPs) were synthesized by stoichiometric amounts of rare earth ions and the cavities in the polymers were created for the corresponding lanthanide ions. The maximum sorption capacities were estimated to be 125.3, 126.5, 127.6, 128.2 and 129.1 mg/g for Pr, Nd, Sm, Eu and Gd, respectively at pH 6. In the selectivity study, the L-IIPs exhibited good selectivity to the specific rare earth ions in the presence of coexisting cations. The imprinting results were found to be excellent with some rare earth ions over other competitor rare earth ions with the same charges and close ionic radius.

Synthesis of poly(hydroxamic acid) ligand from polymer grafted khaya cellulose for transition metals extraction

A cellulose-graft-poly(methyl acrylate) was synthesized by free radical initiating process and the ester functional groups were converted into the hydroxamic acid ligand. The intermediate and final products are characterized by FT-IR, FE-SEM, HR-TEM and XPS technique. The pH of the solution acts as a key factor in achieving optical color signals of metalcomplexation. The reflectance spectra of the [Cu-ligand]n+ complex was found to be a highest absorbance at 99.8 % at pH 6 and it was increased upon increasing of Cu2+ ion concentrations and a broad peak at 700 nm was observed which indicated the charge transfer (π-π transition) metals-Cu complex. The adsorption capacity of copper was found to be superior (336 mg g−1) rather than other transition metals such as Fe3+, Co3+, Cr3+, Ni2+, Mn2+ and Zn2+ were 310, 295, 288, 250, 248 and 225 mg g-1, respectively at pH 6. The experimental data of all metal ions fitted significantly with the pseudo-second-order rate equation. The transition metal ions sorption onto ligand were well fitted with the Langmuir isotherm model (R2>0.99), which suggested that the cellulose-based adsorbent known as poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability of the poly(hydroxamic acid) ligand was checked by the sorption/desorption process up to ten cycles without any significant loss in its original sensing and removal performances.

Synthesis of tapioca cellulose-based poly(hydroxamic acid) ligand for heavy metals removal from water

ABSTRACT A graft copolymerization was performed using free radical initiating process to prepare the poly(methyl acrylate) grafted copolymer from the tapioca cellulose. The desired material is poly(hydroxamic acid) ligand, which is synthesized from poly(methyl acrylate) grafted cellulose using hydroximation reaction. The tapioca cellulose, grafted cellulose and poly(hydroxamic acid) ligand were characterized by Infrared Spectroscopy and Field Emission Scanning Electron Microscope. The adsorption capacity with copper was found to be good, 210 mg g−1 with a faster adsorption rate (t1/2 = 10.5 min). The adsorption capacities for other heavy metal ions were also found to be strong such as Fe3+, Cr3+, Co3+ and Ni2+ were 191, 182, 202 and 173 mg g−1, respectively at pH 6. To predict the adsorption behavior, the heavy metal ions sorption onto ligand were well-fitted with the Langmuir isotherm model (R2 > 0.99), which suggest that the cellulose-based adsorbent i.e., poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability was checked by the sorption/desorption process for six cycles and the sorption and extraction efficiency in each cycle was determined. This new adsorbent can be reused in many cycles without any significant loss in its original removal performances.

Synthesis of Tapioca Cellulose-based Poly(amidoxime) Ligand for Removal of Heavy Metal Ions

ABSTRACT Poly(acrylonitrile)/cellulose block copolymer (PAN-b-cell) was prepared by using a free radical initiating process and then the nitrile functional groups of the PAN blocks of the copolymers were transformed into amidoxime ligands. The resulting poly(amidoxime) ligands could complex with heavy metal ions; for example, the reflectance spectra of the [Cu -ligand]n+ was found to be at the highest absorbance, about 94%, at pH 6. The pH was the key parameter for metal ions sensing by the ligand. The adsorption capacity for copper was very good, 272 mg g−1, with a fast adsorption rate (t1/2 = 10 min). The adsorption capacities for other heavy metal ions such as Fe3+, Cr3+, Co3+ and Ni2+ were also good, being 242, 219, 201 and 195 mg g−1, respectively, at pH 6. The heavy metal ions removal efficiency from water was 98% at low concentration. The data proved that the heavy metal ions adsorption onto the polymer ligands were well fitted with the Langmuir isotherm model (R2>0.99), which suggests that the cellulose-based adsorbent surface namely the poly(amidoxime) ligand, was homogenous and a monolayer. The reusability was examined by a sorption/desorption process for six cycles and the extraction efficiency was determined. This new adsorbent could be reused for 6 cycles without any significant loss in its original removal function.

Hydrothermal synthesis of free-template zeolite T from kaolin

Free-template zeolite T crystals were synthesized via hydrothermal synthesis by utilizing the activated kaolin as silica and alumina source, with the molar composition of 1 SiO2: 0.04 Al2O3: 0.26 Na2O: 0.09 K2O: 14 H2O. Observation of the formation of free-template zeolite crystals were done at temperature 90°C, 100 °C and 110 °C respectively. It was therefore determined that during the 120 h of the synthesis at 90 °C, zeolite T nucleated and formed a first competitive phase with zeolite L. As temperature increases to 100 °C, zeolite T presented itself as a major phase in the system at time 168 h. Subsequently, development of Zeolite T with second competitive phase of zeolite W was observed at temperature 110 °C. In this study, XRD and SEM instruments were used to monitor the behavior of zeolite T crystals with respect of temperature and time. By using natural resource of kaolin clay as a starting material, this paper hence aims to provide new findings in synthesis of zeolite T using low energy consumption and low production cost.

Heavy Metal Removal from Electroplating Wastewater Using Acacia Cellulose Based Polymeric Chelating Ligand

A polymeric chelating ligand containing hydroxamic acid and amidoxime functional groups were prepared from acrylate polymer grafted acacia cellulose and this ligand was introduced to remove heavy metals from industrial wastewaters. The heavy metals binding property with this ligand is excellent up to 3.78 mmol/ g sorbent and the rate of exchange of some metals was very fast i.e. t 1/2 ≈ 6 min (average). Two types of wastewater from electroplating plants used in this study those containing chromium, zinc, nickel, copper and iron etc. Before removing heavy metals from wastewater, pH was adjusted to 4 and various metal concentrations were used for finding the extraction capability of the ligand. It was found that the metals recovery was highly efficient, up to 99.99% of several heavy metals were removed from electroplating wastewater using the ligands. Therefore, the proposed polymeric chelating ligands could be used to the remove such heavy metals from industrial wastewater and as well as effective ligands for environment protection.