Polypyrrole/zeolite composite - A nanoadsorbent for reactive dyes removal from synthetic solution

Synthetic dyes are among the common pollutants in the ecosystem. In the present study, polypyrrole/zeolite (PPy/Ze) nanocomposite was prepared and subsequently assessed for the removal of Reactive blue (RB) and Reactive red (RR) from synthetic solution. The polymeric PPy/Ze composite was synthesized by chemical oxidation of pyrrole in the presence of zeolite. Electron microscopic images (transmission and scanning) indicate that PPy/Ze nanocomposite was spherical in shape with an average size of 40-80 nm. The characteristic pyrrole and zeolite Fourier transform infrared spectrum peaks (1542 cm^-1, 1463 cm^-1, 1156 cm^-1, 1054 cm^-1, 879 cm^-1 and 756 cm^-1) in the nanocomposite confirmed zeolite integration with polypyrrole. Experimental variables such as PPy/Ze nanocomposite dose, initial RB and RR concentration, reaction temperature and pH were optimized. The PPy/Ze nanocomposite adsorbed 86.2% of RB and 88.3% of RR from synthetic solution at optimal conditions (pH 9, initial RR or RB concentration, 75 mg/l; PPy/Ze dose, 1.8 g/l; and temperature, 50 °C). Freundlich isotherm model and pseudo-second-order kinetics showed better fit for both RB and RR removal from synthetic solution. X-ray diffractogram confirmed the amorphous nature of PPy/Ze nanocomposite and that it was not altered even after dye adsorption. Adsorption-desorption studies showed that the composite has satisfactory adsorption potential for four cycles. The results show that the PPy/Ze nanocomposite could be used for the removal of dyes from wastewaters.

Significance of conducting polyaniline based composites for the removal of dyes and heavy metals from aqueous solution and wastewaters - A review

Dyes and heavy metals pollution have become a major environmental concern worldwide. Various methods, such as advanced oxidation, biodegradation, precipitation, flocculation, ultra filtration, ion-exchange, electro-chemical degradation and coagulation, have been proposed for the removal of dyes and heavy metals from contaminated wastewater. Of these methods, adsorption and detoxification are considered as the most promising and economically viable. Polyaniline-based composites, a material prepared by combining polyaniline with one or more similar or disimilar materials, have been reported as good adsorbents to remove and detoxify different groups of pollutants due to their unique physical and chemical properties. In the last decade, several studies have reported the effective adsorption (∼95%) of dyes and heavy metals onto polyaniline based composites. Furthermore, some polyaniline -composites reduced the adsorbed heavy metals into less toxic state. This review compiles the application of different polyaniline composites for adsorption and/or detoxifcation of dyes and heavy metals and documents composite preparation methods, morphology and properties of the composites, and mechanism of dyes and heavy metals adsorption. Based on the avilabile literature, this review suggests that more studies are warranted to understand the influence of various conditions and experimental variables on dyes and heavy metals removal from wastewater and/or aqueous solution.

Glycosylated fibronectin point-of-care test for diagnosis of pre-eclampsia in a low-resource setting: a prospective Southeast Asian population study

OBJECTIVE

To determine the performance of a glycosylated fibronectin (GlyFn) point-of-care (POC) test for pre-eclampsia (PE) in a large Southeast Asian cohort (India) in comparison to previously described biomarkers.

DESIGN

A total of 798 pregnant women at ≥20 weeks of gestation were enrolled in a prospective case-control study. Study participants included 469 normotensive women with urinary mg protein/mmol creatinine ratio <0.3, 135 with PE (hypertension with urinary mg protein/mmol creatinine ratio ≥0.3) and 194 with gestational hypertension (hypertension with urinary mg protein/mmol creatinine ratio <0.3).

METHODS

GlyFn levels were determined using a POC device and PIGF, sFlt-1 and PAPPA2 levels were determined by immunoassay. Performance was assessed using logistic regression modelling and receiver-operating characteristic (ROC) curves. Classification performance and positive and negative predictive values are reported at specific thresholds.

RESULTS

Increased levels of GlyFn, soluble fms-like tyrosine kinase-1 (sFlt-1) and pregnancy-associated placental protein A2 (PAPPA2), and decreased levels of placental growth factor (PlGF) were significantly associated (P < 0.01) with clinically defined PE. Area under the ROC (AUROC) values with 95% confidence intervals were: GlyFn, 0.99 (0.98-0.99); PlGF, 0.96 (0.94-0.98); sFlt-1, 0.86 (0.83-0.89); and PAPPA2, 0.96 (0.94-0.97). Of subjects with GH, 48% were positive for more than two PE biomarkers, and 70% of these delivered preterm.

CONCLUSIONS

The Lumella™ GlyFn POC test has been validated in a low/middle-income country setting for PE diagnosis and may be a useful adjunctive tool for early identification, appropriate triage, and improved outcomes.

TWEETABLE ABSTRACT

The Lumella™ point-of-care test had excellent performance in diagnosing PE in a large Southeast Asian cohort.

Agitated Depression; The Challenges in Management and the Role of Maintenance Electroconvulsive Therapy

This case report highlights the challenges encountered and the role of maintenance electroconvulsive therapy (ECT) in the management of a depressed patient who presented with symptoms of agitation. Despite on an adequate dosage and duration of medications, the patient showed poor improvement and persistent agitation. Upon commencing maintenance ECT in addition to the pharmacotherapy, the patient’s condition markedly improved. As conclusion, maintenance ECT may be another option in managing agitated depression.

Key Authentication Scheme-based on Discrete Logarithms and Chinese Remainder Theorem

<p>Public key cryptosystems are secure only when the authenticity of the public key is assured. Shao proposed<br />a new scheme to overcome the problems of the existing schemes, which suffers from two major drawbacks. The<br />first drawback is the availability of users’ passwords in plaintext format in key server which are prone to attacks<br />by ill-minded users. The second one is depending on the key server blindly for certificate generation, without<br />further verification by the user. To overcome these severe drawbacks, we proposed an improved key authentication<br />scheme based on Chinese remainder theorem and discrete logarithms. Our scheme allows the user to generate his/<br />her certificate without the help of any trusted third party. This scheme is intended for online services, military and<br />defense applications to exchange keys securely.<br /> </p>

Competitive adsorption of Reactive Orange 16 and Reactive Brilliant Blue R on polyaniline/bacterial extracellular polysaccharides composite--a novel eco-friendly polymer

The performance of polyaniline/extracellular polymeric substances (Pn/EPS) composite as an adsorbent to remove the anionic reactive dyes, Reactive Brilliant Blue R (RBBR) and Reactive Orange 16 (RO), was investigated in single and binary systems. The pH(pzc) of Pn/EPS composite was calculated as 3.7 through potentiometric mass titration method. Electrostatic interaction between the dye anion and the nitrogen present in the polymer was identified as a major mechanism in adsorption process. Single component isotherms followed the Langmuir model with the maximum adsorption capacity of 0.5775 mmol g(-1) for RBBR and 0.4748 mmol g(-1) for RO. In binary system, both the reactive dye anions compete with each other and resulted in lower uptake. Binary adsorption data were interpreted well by the Sheindorf-Rehbun-Sheintuch equation as compared to extended Langmuir model with constant interaction factor. Kinetic analysis of single solute followed pseudo-first order model. Thermodynamic studies computed that RBBR and RO adsorption was endothermic, spontaneous, and feasible process.

Starch/polyaniline nanocomposite for enhanced removal of reactive dyes from synthetic effluent

Starch/polyaniline nanocomposite was synthesized by chemical oxidative polymerization of aniline and was subsequently analyzed for dye removal from aqueous solution. Batch experiment results showed that nanocomposite removed 99% of Reactive Black 5, 98% of Reactive Violet 4, and decolorized 87% of dye bath effluent. The Toth isotherm model better described single component equilibrium adsorption, whereas the modified Freundlich model showed satisfactory fit for dye bath. In kinetic modeling, single system followed pseudo-second-order and dye bath followed the modified pseudo-first-order model. Fourier transform infrared spectroscopy pattern of the nanocomposite showed the participation of aromatic, amino, hydroxyl, and carboxyl groups. The results indicate that starch/polyaniline nanocomposite can be used as an effective adsorbent for removal of dyes from textile effluents.