New Modified Electrodes of Graphite paste with Nano Silicon dioxide For Determination of Sildenafil citrate Drug

In this research, new graphite paste electrodes modified with silicon dioxide (SiO2) nano particle are constructed and used for the determination of Viagra drug (Sildenafil citrate, SILC). The electrodes are constructed by preparing ion-pair for (SILC) with phosphotungstic acid (PTA) or phosphomolybdic (PMA) acid using dibutyl phthalate (DBP) as a plasticizer. These electrodes show good sensitivity towards SILC with linear range of (1.0´10-7-1.0´10-2) M, correlation coefficient, (0.9990) and the life time (120) days for both electrodes, limit of detection (5.177´10-8 and 5.026´10-8) M, optimum temperature range (23-50 and 23-65)oC , slope (57.33 and 58.01) mV/decade and optimum pH range (2-6 and 2-5), for SILC-PTA and SILC-PMA electrodes respectively. These electrodes were successfully applied for determination of SILC in pure and pharmaceutical preparation form (tablets) with recovery of not less than 98% . http://dx.doi.org/10.25130/tjps.24.2019.109

Conversion of solid waste to activated carbon to improve landfill sustainability

Heterogeneous composite wastes from landfills were evaluated as precursors for the generation of activated carbon (AC). A single-step chemical activation process was applied involving irradiation with microwave energy and impregnation with KOH. The average percentage yield of AC from active landfill precursor was higher than that from closed landfill for all depths sampled. Increase in impregnation ratio and irradiation power decreased the average percentage yield for both landfill precursors (active: 38.1 to 33.1%; closed: 42.1 to 33.3%). The optimum pH range for adsorption of methylene blue was pH 6–7, while adsorption increased with increase in temperature over the range 30 to 50°C. Carbonyl and hydroxyl groups were the major functional groups on the surface of AC. The properties of the AC are potentially suitable for the removal of cationic dyes and pollutants. AC generated from the landfill composite was comparable to that from other biomass being managed through AC generation. This is the first report to demonstrate the possible reuse of landfill composite as AC. The reuse option of landfill composite could provide a means of sustainable management of landfilled municipal waste.

Biosorption characteristics of Spirulina and Chlorella cells to accumulate heavy metals

The heavy metal biosorption of dried Chlorella vulgaris and Spirulina platensis-Spirulina maxima cells was studied under various experimental conditions. The effect of biosorbent dosage, pH, adsorption time, temperature, initial metal concentration on biosorption was studied. Biosorption process can be divided into two parts: the first part follows zero-order, the second part pseudo second-order kinetics. Characterization of biosorption equilibrium was evaluated with Langmuir and Dubinin-Radushkevich models using non-linear regression. The optimum pH range was found to be 5.0 ? 6.0 for Pb(II) and 4.0 ? 6.0 for Cu(II) and Cd(II) adsorption. The maximum adsorption capacities for Pb(II), Cd(II) and Cu(II) were 144, 161 and 138 mg g-1 by Chlorella cells and 370, 201 and 165 by Spirulina cells, based on the experimental data. The same values for activated carbon were 86, 134 and 43 mg g-1, respectively.

Adsorptive Removal of Reactive Dyes from Aqueous Solution by Cationic Polyelectrolyte Modified Bentonite

This study reports on the modification of natural bentonite by a cationic polyelectrolyte, which is a lignin-based aldehyde-ketone resin, and the application of this modified clay as adsorbent in the removal of reactive dyes from aqueous solution. Modified bentonite was characterized by IR and zeta-potential test, its dye removal performance was evaluated. Results show that intermolecular interaction and electrostatic attraction between dyes and adsorbent are responsible for the adsorption behavior. The removal of reactive dyes increased with increasing temperature and the optimum pH range was 4.0-6.5. The negative values of ΔG reflected the spontaneous adsorption and the values of ΔH showed that it was a combination of chemical and physical adsorption. Equilibrium adsorption data fitted well to Langmuir isotherm and the adsorption capacity for reactive red and reactive blue was 125.0 and 159.2 mg/g, respectively.

Thermostable Alkaline Phytase from Alcaligenes sp. in Improving Bioavailability of Phosphorus in Animal Feed: In Vitro Analysis

A bacterial isolate, Alcaligenes sp. secreting phytase (EC 3.1.3.8), was isolated and characterized. The optimum conditions for the production of phytase included a fermentation period of 96 h, pH 8.0, and the addition of 1% (w/v) maltose and 1% (w/v) beef extract to the culture medium. This enzyme was purified to homogeneity and had an apparent molecular mass of 41 kDa. The optimum pH range and temperature for the activity of phytase were found to be 7.0-8.0 and 60°C, respectively. This enzyme was strongly inhibited by 0.005 M of Mn2+, Mg2+, and Zn2+. In vitro studies revealed that the phytase from Alcaligenes sp. released inorganic phosphate from plant phytates. Phytase released 1930 ± 28, 1740 ± 13, 1050 ± 31, 845 ± 7, 1935 ± 32, and 1655 ± 21 mg inorganic phosphate/kg plant phytates, namely, chick pea, corn, green pea, groundnut, pearl pea, and chick feed, respectively.

Investigation on coagulation efficiency of polyaluminium silicate chloride (PASiC) coagulant

Polyaluminium silicate chloride (PASiC) coagulant was synthesized by co-polymerization technique using aluminium salt and polysilicic acid at different OH/Al and Al/Si molar ratios. A synthetic turbid sample was used to investigate the coagulation efficiency of the prepared coagulant. After the coagulant dosing, flocculation time was set for 15 minutes followed by sedimentation for 20 minutes. High performance of coagulant was achieved at 2.5 molar ratio of OH/Al and 5 molar ratio of Al/Si at the optimal pH. The optimum pH range was found to be 7±0.5.The effective coagulant dose for the efficient removal of turbidity was set as 2.5 mg/L. As compared to conventional alum, PASiC has been found to be excellent inorganic polymeric coagulant for turbidity removal from water and residual aluminum was found to be minimal in comparison to conventional alum treatment. Hence, PASiC has proven the potentiality for the turbidity removal in water treatment over conventional alum. Scientific World, Vol. 10, No. 10, July 2012 p33-37 DOI: http://dx.doi.org/10.3126/sw.v10i10.6859

Synthesis of Dendrimer-Like Polyamidoamine on Silica Gel Surface and their Adsorption Properties for Cr 3+

Amino functional silica gel was synthesized by in-situ hydrolysis method in the present of silane coupling agent. Then dendrimer-like polyamidoamines based on the silica gel surface (PAMAM-SG) were prepared using Micheal addition of the amino and methyl acrylate, and ester-exchange of ethylene diamine and the ester group. The effects of solution pH, concentration and temperature on the adsorption capacity of PAMAM-SG for Cr3+were studied. The optimum pH range is 4.0-7.0. The adsorption rate decreased with increasing the time, but increased with increasing the temperature. The adsorption capacity increased with increase of the concentration until the adsorption reached equilibrium. The adsorption capacity increased with the generations of PAMAM-SG.

Reduction of COD from Micro-Polluted Water through Adsorption of Activated Carbon-Attapulgite Composite Adsorbent

The aim of this study was the assessment of reduction of chemical oxygen demand (COD) from micro-polluted water using activated carbon-attapulgite composite adsorbent prepared using activated carbon and natural attapulgite through compounding, granulation and calcination. The complete study was done in batch mode to investigate the effect of operating parameters. Adsorption of COD was found to be dependent on contact time, pH, temperature and initial COD concentration. Adsorption equilibrium attained within 80 minutes time. The optimum pH range for adsorption of organics was found to be 8. The sorption of organics decreased with rise of temperature because adsorption process was exothermic. The studied adsorption data fitted well to Langmuir adsorption model with the correlation coefficient 0.9947. The activated carbon-attapulgite composite adsorbent in this study shows very good promise for practical applicability on removal of COD from micro-polluted water.

Removal of Pb(II) from Aqueous Solution Using Composite Filter Material Made of Fly Ash

Adsorption of Pb(II) on composite filter material mainly made of fly ash was investigated for the removal of Pb(II) from aqueous solution. Batch experiments have been carried out for adsorption of Pb(II) on to this composite filter material. The effects of various parameters influencing the Pb(II) adsorption such as contact time, initial pH, different dosage of adsorbent and temperature have been studied. Results showed that adsorption equilibrium attained within 60 minutes time. Increase in adsorbent dosage led to increase in Pb(II) adsorption due to increased number of adsorption sites. Adsorption process was found to be highly pH dependent, and the optimum pH range for adsorption of Pb(II) was found to be >8.5. The sorption of Pb(II) increased with rise of temperature.

Coagulation/flocculation of dye-containing solutions using polyaluminium chloride and alum

This study aims to compare the performance of Polyaluminium Chloride (PAC) and alum as coagulants to remove a specific type of dye (Acid Blue 292 (AB292)) from dye-containing solution. For this purpose, the influence of pH, coagulant dosage, coagulant aids (kaolinite and bentonite), and initial dye concentration on dye removal efficiency were examined. According to the results, removal of AB292 was absolutely dependent on the pH variations. The maximum dye removal occurred when pH was 7 and 5 for PAC and alum, respectively. Both coagulants efficiently removed the dye (about 85%) with a relatively low dosage (40 mg/l) in their optimum pH range. By adding kaolinite as a coagulant aid, the removal efficiencies tended to increase, especially for lower dosages of PAC and alum. With the increase of initial dye concentration, PAC and alum represented different behaviors. In the case of PAC, Q (the amount of the removed dye per unit mass of coagulant) increased at first and reached to a maximum value, 2.1 mg dye/mg PAC, and then decreased rapidly. While for alum, Q steadily increased with the increase of dye concentration and reached to 2.8 mg dye/mg alum. No reduction of Q occurred for alum with the increase of dye concentration in the range of 25–250 mg/l.