Sawdust: A green and economical sorbent for thallium removal

Removal/preconcentration of thallium(I) ions from aqueous solution by sawdust; a waste material derived from the commercial processing of Cedrus Deodar wood for furniture production was investigated. A simple and low-cost modification results in increasing the sorption capacity of raw sawdust from 2.71 to 13.18 mg g⁻¹. Sorption was found to be rapid (98% within 8 min). The binding of metal ions was found to be pH dependent, optimal sorption accruing at around pH 6–9. Potentiometeric titrations of sawdust revealed two distinct pK_a values, the first having the value similar to carboxylic groups (3.3–4.8) and second comparable with that of amines (8.53–10.2) with the surface site densities of 1.99 × 10⁻⁴ and 7.94 × 10⁻⁵ mol g⁻¹, respectively. Retained Tl(I) ions were eluted with 5 ml 0.1 mol l⁻¹ HCl. Detection limit of 0.0125 μg ml⁻¹ was achieved with an enrichment factor of 160. Recovery was quantitative using sample volume of 800 ml. The Langmuir, Freundlich and D–R isotherm equations were used to describe partitioning behavior for the system at different temperatures. Kinetic and thermodynamic behavior of sawdust for Tl(I) ions removal was also studied.     

Selective Electroanalytical Method for the Determination of Roxarsone in Poultry Feed and Litter

An extremely sensitive and selective voltammetric method was developed for the determination of roxarsone (ROX) at a newly modified carbon paste microelectrode in Britton–Robinson buffer (BRB) at pH 2.0. The electrode is based on a disposable plastic pipette tip filled with carbon paste based on a mixture of graphite powder and Amberlite XAD-4 (5:1, w/w). The experimental parameters, such as pH, type of the buffer, mode of voltammetry, accumulation potential, accumulation time, and stirring rate were optimized. The reduction peak current dependences were linear for the concentration of ROX from 2.0 to 100 μM. The method showed reproducible results with RSD (n?=?11) of <2.0 %. The limit of detection (LOD) and limit of quantification (LOQ) were 0.53 and 1.76 μM, respectively. ROX showed that there was no apparent surface passivation indicating the suitability of the modified electrode for ROX detection. The developed method was successfully applied for the determination of ROX in poultry feed and poultry litter collected from various localities of Hyderabad.     

Survey of grid-connected photovoltaic inverters and related systems

Grid-connected photovoltaic (PV) inverter technology has advanced since it first attracted the attention of policy makers. The objective of this article is to present a survey of grid-connected PV inverters and their present technology in Malaysia. Surveyed here are 186 PV inverter products from 22 manufacturers, their power factors, system THDs, efficiencies, power inputs (from PV array), costs, sizes, and protections investigated, and their datasheets collected from various manufacturers in Europe, North America, and Asia. The data are compared within regions and subject headings. Discussed are the lowering of cost, the raising of efficiency levels, and reliability improvement.     

Nephrotic syndrome, renal failure, and renal malignancy: an unusual tumor-associated glomerulonephritis

The association between malignancy and glomerular disease has been appreciated for over three decades. Although the relationship between membranous glomerulonephritis or minimal-change nephrotic syndrome and carcinoma or lymphoma, respectively, are the most widely known, several other glomerular lesions have been described in patients with malignancy. In this article, a patient who presented with nephrotic syndrome, volume overload, and renal failure, who was subsequently found to have a renal mass, is described. Resection of the mass, which proved to be a renal cell carcinoma, led to resolution of proteinuria and improvement of renal function. Pathology on the noninvolved portion of the kidney revealed a membranoproliferative glomerular lesion, a lesion usually associated with lymphomas and not previously described with renal carcinoma. Although a role of tumor antigens and anti-tumor antibodies in producing glomerular immune deposits has been speculated upon, the evidence for this assertion was spotty. However, reports of remission of proteinuria after tumor treatment or removal support a role of tumor products in pathogenesis. Although the association between proteinuria and malignancy is rare, it should be kept in mind, particularly in older patients with membranous glomerulonephritis where the possibility of malignancy needs to be further evaluated.     

Ultra-fast catalytic reduction of dyes by ionic liquid recoverable and reusable mefenamic acid derived gold nanoparticles

We synthesized mefenamic acid (MA) derived gold nanoparticles (MA-AuNps) in aqueous solution (MA-Au sol). Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) of the sol at 1, 5, 15 and 60 min showed changes in size and shape of formed AuNps. Fourier Transform Infrared (FTIR) Spectroscopy revealed the interaction between AuNps and MA. Each Au sol exhibited exceptional catalytic activity for the reduction of Methylene Blue (MB), Rose Bengal (RB) and Eosin B (EB) dye individually as well as collectively. However, complete reduction of dye(s) was accomplished by Au sol of 5 min in just 15s. The catalytic performance of Ma-Au sol was far superior to that adsorbed on glass. AuNps were recovered with the help of water insoluble room temperature ionic liquid and reused with enhanced catalytic potential. This finding is a novel, rapid and highly economical alternative for environmental safety against pollution by dyes and extendable for control of other reducible contaminants as well.     

Synthesis of calix[6]arene based XAD‐4 material for the removal of reactive blue 19 from aqueous environments

This study describes the synthesis of calix[6]arene (C6) appended Amberlite XAD‐4 resin and its application for the removal of anthraquinone‐based reactive blue 19 (RB‐19) dye from aqueous environments. The C6‐resin 5 was characterized with various analytical techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis. Adsorption experiments were carried out to investigate the effects of the pH, adsorbent dosage, electrolyte, contact time, and temperature on the adsorption of RB‐19 dye onto the C6‐resin 5. From the results, we observed that the percentage adsorption of the RB‐19 dye was highly dependent on the concentration of electrolyte and the pH of the solution. The maximum adsorption was achieved at pH 9. The thermal study demonstrated that the adsorption process was endothermic and spontaneous in nature. The isothermic study showed that the adsorption behavior could be better demonstrated by the Langmuir and Dubinin and Radushkevich isotherm model. From field studies, it has been concluded that C6‐resin 5 is an effective adsorbent for the removal of RB‐19 dye. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 776‐785, 2013     

Synthesis and application of calix[4]arene based resin for the removal of azo dyes

The present study describes a novel synthetic method for the immobilization of calix[4]arene (II) onto the surface of modified Amberlite XAD-4 resin (4), which does not require the derivatization of calixarene moiety. The novel calix[4]arene based resin (C4 resin) 5 was used as sorbent for the removal of azo dyes. Batch-wise sorption study was carried out and observed that the C4 resin (5) is more effective as compared to compound II as well as pure Amberlite XAD-4 resin (1) to remove the selected dyes [i.e. Reactive Black-5 (RB-5), Reactive Red-45 (RR-45) and Congo Red (CR)]. The effect of sorbent dosage and pH on % sorption was studied. During the extraction process, various kinds of interactions such as electrostatic repulsion, deprotonation of the hydroxyl groups of C4 resin, dissociation of reactive dyes into anions/cations and structural variations were monitored and found that they are highly pH dependent.     

Strategic analysis of single-use plastic ban policy for environmental sustainability: the case of Pakistan

Clean Technologies and Environmental Policy - One of the challenging tasks for governments is to curtail the production and consumption of single-use plastic bags. Despite multiple advantages of...