Removal of Transition-Metal Ions by Metal-Complexing Polythiosemicarbazone Membranes

Membrane technology is one of the many strategies to remove transition-metal ions from aqueous streams because of its relatively lower costs and ease of operation. Typically, adsorbent materials are added into polymeric membranes to impart chelating/complexing properties, but this often results in a limited number of adsorption sites within the membrane. In this work, polythiosemicarbazone (pTSC) is proposed as a material to prepare polymeric membranes due to its metal-complexing ligands in the backbone, providing more adsorption sites. The polymer was easily processed into membranes via the nonsolvent-induced phase separation technique and exhibited asymmetric structures with adequate mechanical strength. The porosity of the membranes was controlled by increasing the polymer concentration in the casting solution, leading to ultrafiltration- and nanofiltration-type membranes with permeabilities ranging from 30 to 0.7 L·m-2·h-1·bar-1. The resulting pTSC membranes were applied for the removal of silver and copper ions in batch and, in the case of silver ions, also in dynamic adsorption experiments. The maximum removal rate of 17 mg·g-1 for silver and 3.8 mg·g-1 for copper ions was obtained in the batch removal experiment. Streaming potential, pH measurements, and infrared spectroscopy (FTIR) were conducted to verify the anionic binding of TSC groups, while neutral binding modes were revealed by FTIR and batch removal experiments. Furthermore, the removal of silver ions was also successfully demonstrated in a flow setup operated at 4 bar of applied pressure. The streaming potential and energy-dispersive X-ray (EDX) spectroscopy conducted on the membranes after the flow tests confirmed the complexation by TSC-functional groups as the separation mechanism. Finally, partial desorption of the silver ions was successfully conducted in water to demonstrate the reusability of pTSC membranes.</p

Removal of Transition-Metal Ions by Metal-Complexing Polythiosemicarbazone Membranes

Membrane technology is one of the many strategies to remove transition-metal ions from aqueous streams because of its relatively lower costs and ease of operation. Typically, adsorbent materials are added into polymeric membranes to impart chelating/complexing properties, but this often results in a limited number of adsorption sites within the membrane. In this work, polythiosemicarbazone (pTSC) is proposed as a material to prepare polymeric membranes due to its metal-complexing ligands in the backbone, providing more adsorption sites. The polymer was easily processed into membranes via the nonsolvent-induced phase separation technique and exhibited asymmetric structures with adequate mechanical strength. The porosity of the membranes was controlled by increasing the polymer concentration in the casting solution, leading to ultrafiltration- and nanofiltration-type membranes with permeabilities ranging from 30 to 0.7 L·m$^{–2}$·h$^{–1}$·bar$^{–1}$. The resulting pTSC membranes were applied for the removal of silver and copper ions in batch and, in the case of silver ions, also in dynamic adsorption experiments. The maximum removal rate of 17 mg·g$^{–1}$ for silver and 3.8 mg·g$^{–1}$ for copper ions was obtained in the batch removal experiment. Streaming potential, pH measurements, and infrared spectroscopy (FTIR) were conducted to verify the anionic binding of TSC groups, while neutral binding modes were revealed by FTIR and batch removal experiments. Furthermore, the removal of silver ions was also successfully demonstrated in a flow setup operated at 4 bar of applied pressure. The streaming potential and energy-dispersive X-ray (EDX) spectroscopy conducted on the membranes after the flow tests confirmed the complexation by TSC-functional groups as the separation mechanism. Finally, partial desorption of the silver ions was successfully conducted in water to demonstrate the reusability of pTSC membranes

Evaluation of hepatoprotective effect of chloroform and methanol extracts of <i>Opuntia monacantha</i> in paracetamol-induced hepatotoxicity in rabbits

The chloroform and methanol extracts of Opuntia monacantha were studied for its hepatoprotective effect against paracetamol induced liver damage in rabbits. Results proved that both extracts at 200, 400 and 600 mg/kg body weight in one week protocol showed significant (p<0.001) hepatoprotective activity by reducing the magnitude of liver markers including alanine aminotransferase, aspartate aminotransferase, alkaline phasphatase and total bilirubin levels. The results were supported by histopathological studies of liver tissue. Chemical analysis of O. monacantha indicated the presence of alkaloids, tannins, saponins, flavonoids and  polysaccharides and its hepato-protective potential may be due to the presence of flavonoids. Its is concluded that 600 mg/kg is the potent dose of both extracts of O. monacantha as hepatoprotective plant

Polyelectrolyte Complex Hollow Fiber Membranes Prepared via Aqueous Phase Separation

Hollow fiber (HF) membrane geometry is the preferred choice for most commercial membrane operations. Such fibers are conventionally prepared via the non-solvent-induced phase separation technique, which heavily relies on hazardous and reprotoxic organic solvents such as N-methyl pyrrolidone. A more sustainable alternative, i.e., aqueous phase separation (APS), was introduced recently that utilizes water as a solvent and non-solvent for the production of polymeric membranes. Herein, for the first time, we demonstrate the preparation of sustainable and functional HF membranes via the APS technique in a dry-jet wet spinning process. The dope solution comprising poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) at high pH along with an aqueous bore liquid is pushed through a single orifice spinneret into a low pH acetate buffer coagulation bath. Here, PEI becomes charged resulting in the formation of a polyelectrolyte complex with PSS. The compositions of the bore liquid and coagulation bath were systematically varied to study their effect on the structure and performance of the HF membranes. The microfiltration-type membranes (permeability ∼500 to 800 L·m–2·h–1·bar–1) with complete retention of emulsion droplets were obtained when the precipitation rate was slow. Increasing the concentration of the acetate buffer in the bath led to the increase in precipitation rate resulting in ultrafiltration-type membranes (permeability ∼12 to 15 L·m–2·h–1·bar–1) having molecular weight cut-offs in the range of ∼7.8–11.6 kDa. The research presented in this work confirms the versatility of APS and moves it another step closer to large-scale use

Detection, quantification and genotype distribution of HCV patients in Lahore, Pakistan by real-time PCR

Background: Hepatitis C virus (HCV) is considered as \u201cViral Time Bomb\u201d suggested by the World Health Organization and if it is not treated timely, it will lead towards cirrhosis and hepatocellular carcinoma (HCC). Objective: The purpose of the present research is to study possible risk factors, frequent genotypes of HCV and its association with different age groups. Methods: Suspected blood samples from HCV patients were collected from different hospitals of Lahore, Pakistan. Out of 1000 HCV suspected samples, 920 samples were found HCV positive detected by Anti-HCV ELISA, CobasR. kit. The quantification of HCV load was determined by HCV quantification kit and LINEAR ARRAY KIT (Roche) was used for genotype determination by Real-Time PCR (ABI). Statistical analysis was done by using Microsoft Excel. Results: Out of 920 subjects, 77 subjects (8.4%) were false positive and they were not detected by nested PCR. Three PCR positive samples were untypeable. Genotype 3 was predominant in Lahore which was 83.5%, whereas type 1 and 2 were 5.1% and 0.7% respectively. There were also mixed genotypes detected, 1 and 3 were 0.4%, 2 and 3 were 1.41% and 3 and 4 were 0.2% only. Male were more infected of HCV in the age &lt;40 years and females &gt;40years. Conclusion: The major risk factor for HCV transmission is by use of unsterilized razors/blades. It is necessary to spread awareness among the general population of Pakistan about HCV transmission risk factors. Regular physical examination at least once a year is recommended, so that early detection of HCV could be done

Sustainable Polyelectrolyte Complex Membranes Produced via Aqueous Phase Separation

Polymeric membranes are typically prepared using a technique known as the non-solvent induced phase separation (NIPS). In this technique, a polymer is first dissolved in an organic solvent such as N-methyl pyrrolidone (NMP), and immersed in a non-solvent bath which typically comprise of water. Due to the insolubility of the polymer in water, it precipitates as a solid porous membrane. The polymer solution thermodynamics and the membrane precipitation kinetics can be controlled to obtain membranes with desired morphology and separation performance. For decades, NIPS has been the primary production method to produce commercial polymeric membranes. However, the largest downside of this technique is its reliance on organic solvents like NMP which are reprotoxic, harmful for the environment, and therefore, unsustainable. Owing to these facts, the European Union has restricted the use of NMP and there are increasing demands to utilize more sustainable alternatives for polymeric membrane production. In this thesis, we alleviate this problem by utilizing a safe and sustainable solvent, i.e. water. We demonstrate that water can be used as a solvent and a non-solvent for polyelectrolytes depending on its pH. When two oppositely charged polyelectrolytes are mixed, they form a polyelectrolyte complex (PEC), which is typically insoluble in water. A weak and a strong polyelectrolyte can be mixed to obtain a homogeneous solution at high pH, where the weak polyelectrolyte is uncharged. Immersing such a solution in low pH bath causes the weak polyelectrolyte to acquire charge and form a polyelectrolyte complex with the strong polyelectrolyte. The newly formed PEC is insoluble in water and precipitates as a solid porous membrane. In this thesis, several tuning parameters such as the molecular weight of the polyelectrolytes, the polymer solution concentration, the polyelectrolyte mixing ratio, and the precipitation bath conditions were investigated to obtain membranes with desired morphology and separation performance. Such parameters provide similar control over the membrane structure as in NIPS. Sustainable membranes for micro-, ultra-, and nanofiltration applications were successfully produced utilizing this new aqueous phase separation (APS) technique. Additionally, the versatility of this new technique was established by successfully producing sustainable hollow fiber membranes. The research work presented in this thesis opens up a new field of sustainable membranes and hopefully will be a stepping stone for further research on green fabrication technologies

Phytochemical Analysis and Antioxidant Potential of Ficus Benghalensis L.

Genus Ficus belongs to family Moraceae having 40 genera and over 1000 species worldwide. Different methods have been used for phytochemical screening of medicinal plants like total phenolics content (TPC) and total flavonoids content (TFC) assays to quantify phenolics and flavonoids. The phytochemical analysis exhibited highest total phenolics content in M extract of stem and total flavonoids content in ethyl acetate (EA) extract of leaves i.e. 61.2±1.3 µg GAE/mg extract and 25.1±0.9 µg QE/mg extract respectively. Total reduction power and total antioxidant capacity were maximum in the M extract of stem i.e. 243.89±1.6 µg AAE/mg extract and 127.08±2.7 µg AAE/mg extract respectively

Aqueous phase separation technology

Polymeric membranes are ubiquitous in numerous applications, including kidney dialysis, water treatment, gas separation, energy generation, and storage. It is ironic that the membranes typically used to provide sustainable solutions are themselves produced using reprotoxic organic solvents. The unsustainability of such solvents has led to the development of greener alternatives, out of which, aqueous phase separation (APS) is especially promising. Membranes with tunable properties are prepared in a completely aqueous approach without using organic solvents. Here, we summarize the state-of-the-art regarding APS membranes, demonstrating a great deal of versatility in terms of properties and performance.</p