Kinetic, equilibrium and thermodynamic modelling of the sorption of metals from aqueous solution by a silica polyamine composite

Batch sorption studies were conducted to assess the potential of a phosphonated silica polyamine composite (BPAP) to remove metals (Co, Cu, Fe, Mg, Mn, Ni, U and Zn) from mine waters. The metal adsorption showed a good Langmuir isotherm fit. Ni and Mn fitted both the Freundlich and Langmuir isotherms. The activation energies (Ea) of Co, Mg and Ni ranged between 5 and 40 kJ∙moℓ-1, signifying physisorption while U showed a chemisorption type of adsorption (with Ea > 50 kJ∙moℓ-1). Cu and Fe on the other hand gave negative Ea values, indicating their preference to bind to low-energy sites. The pseudo-second-order kinetic model provided the best correlation of the experimental data, except for Mg and Ni for which the pseudo-first-order model and the Elovich model gave a better fit, respectively. Adsorption was almost constant over a wide pH regime and increased with time. Adsorption increased with concentration of the metals with the exception of Co, Fe and Ni which displayed about a 40% drop at a concentration of 200 mg∙ℓ-1. Desorption experimental data gave poor results except for U which showed 99.9% desorption.Keywords: silica polyamine composite, sorption, kinetics, isotherms, desorptio

Serum protein profile in patients with pulmonary tuberculosis

A detailed study of the alterations in the serum protein fractions following commencement of effective anti-tuberculosis treatment was undertaken in 511 patients with pulmonary tuberculosis. The concentration of serum albumin was 20-30 per cent higher (P<0.001) and that of a1, a2 and g -globulins significantly lower at the end of treatment than on admission (P <0.01), the magnitude of decrease being 7-17 per cent for g -globulin, 19-30 per cent for a1- globulin and 35-38 per cent for a2- globulin. In all, 481 patients had a favourable response to treatment, 46 of whom had a bacteriological relapse within 18 months of stopping treatment. The likelihood of a relapse was found to be greater with higher a2 -globulin concentrations at the end of treatment, the proportions of patients who relapsed being 3, 9, 13 and 15 per cent with a2 -globulin concentrations of < 0.40, 0.40-0.59, 0.60-0.79 and > 0.80 g/dl (P=0.02)

Classification of Subjects as Slow or Rapid Inactivators of Isoniazid Based on the Ratio of Acetylisoniazid to Isoniazid in Urine Determined by a Simple Colorimetric Method

A method for classifying subjects as slow or rapid inactivators of isoniazid based on the ratio of acetylisoniazid to isoniazid in a 3-4 hour urine collection following an intramuscular dose of isoniazid 3 mg./kg. body-weight has been described. Isoniazid and acetylisoniazid have been estimated using methods requiring the use of only a photoelectric colorimeter. Of the 279 patients investigated, 169 (61 per cent) were classified as slow inactivators and 110 (39 per cent) as rapid inactivators. This classification is an excellent agreement (97 per cent) with that based on a standard spectrophotometric method

Nanoporous Silica Polyamine Composites for Metal Ion Capture From Rice Hull Ash

Rice Hull Ash (RHA) was converted to amorphous silica gel using a modified version of published literature procedures. The gels were characterized by a comparison of their CPMAS [29] Si NMR and Scanning Electron Microscopy (SEM) images with commercial silica gels. The resulting gels were silanized with a 7.5:1 mixture of methyltrichlorosilane and chloropropyltrichlorosilane and then reacted with poly(allylamine) (PAA) to produce the silica polyamine composite (SPC) BP-1. The BP-1 was then further modified with pyridine-2-carboxaldehyde to form the copper selective SPC, CuSELECT. This procedure follows that used to produce the commercialized version of these composite materials from commercially available amorphous silica gels. The composites were characterized by solid state NMR techniques, elemental analysis, SEM, porosimetry, and metal ion capacity and selectivity. The overall goal of the project was to determine the feasibility of using RHA to make SPC. The observed strengths and weaknesses of this approach are discussed

Pore confinement effects and stabilization of carbon nitride oligomers in macroporous silica for photocatalytic hydrogen production

An ordered macroporous host (mac-SiO2) has been used to prevent aggregation of layered photocatalysts based on carbon nitride. Using typical carbon nitride synthesis conditions, cyanamide was condensed at 550 °C in the presence and absence of mac-SiO2. Condensation in the absence of mac-SiO2 results in materials with structural characteristics consistent with the carbon nitride, melon, accompanied by ca. 2 wt% carbonization. For mac-SiO2 supported materials, condensation occurs with greater carbonization (ca. 6 wt%). On addition of 3 wt% Pt cocatalyst photocatalytic hydrogen production under visible light is found to be up to 10 times greater for the supported composites. Time-resolved photoluminescence spectroscopy shows that excited state relaxation is more rapid for the mac-SiO2 supported materials suggesting faster electron-hole recombination and that supported carbon nitride does not exhibit improved charge separation. CO2 temperature programmed desorption indicates that enhanced photoactivity of supported carbon nitride is attributable to an increased surface area compared to bulk carbon nitride and an increase in the concentration of weakly basic catalytic sites, consistent with carbon nitride oligomers

Tuberculosis chemotherapy: current drug delivery approaches

Tuberculosis is a leading killer of young adults worldwide and the global scourge of multi-drug resistant tuberculosis is reaching epidemic proportions. It is endemic in most developing countries and resurgent in developed and developing countries with high rates of human immunodeficiency virus infection. This article reviews the current situation in terms of drug delivery approaches for tuberculosis chemotherapy. A number of novel implant-, microparticulate-, and various other carrier-based drug delivery systems incorporating the principal anti-tuberculosis agents have been fabricated that either target the site of tuberculosis infection or reduce the dosing frequency with the aim of improving patient outcomes. These developments in drug delivery represent attractive options with significant merit, however, there is a requisite to manufacture an oral system, which directly addresses issues of unacceptable rifampicin bioavailability in fixed-dose combinations. This is fostered by the need to deliver medications to patients more efficiently and with fewer side effects, especially in developing countries. The fabrication of a polymeric once-daily oral multiparticulate fixed-dose combination of the principal anti-tuberculosis drugs, which attains segregated delivery of rifampicin and isoniazid for improved rifampicin bioavailability, could be a step in the right direction in addressing issues of treatment failure due to patient non-compliance

Active removal of waste dye pollutants using Ta[sub]3N[sub]5/W[sub]18O[sub]49 nanocomposite fibres

A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta3N5 nanoparticles and WOx≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W18O49. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta3N5 nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W18O49 component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors’ knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale

Levonorgestrel hormone releasing intrauterine system (Mirena) as a contraceptive in egg donors: case report

We report the safe use of levonorgestrel hormone releasing intra uterine system (Mirena®) as a contraceptive in egg donors during a treatment cycle. In the first case report, a 29-year-old egg donor using the Mirena coil for contraception and two egg recipients, aged 41 years and 32 years respectively underwent standard IVF treatment, oocyte retrieval in the egg donor and in vitro fertilization followed by embryo transfer in the recipient. The outcome of IVF cycle using donor eggs was satisfactory with successful pregnancy in the egg recipient. The second case involved a 34-year-old egg donor using the Mirena coil and a 44-year-old recipient. Our findings suggest that egg donors can safely use the (Mirena®) as a contraceptive device during treatment, without compromising follicular development and oocyte quality