Ali N. Siyal

Optimization and equilibrium studies of Pb(II) removal by Grewia Asiatica seed: a factorial design approach

Optimization and equilibrium studies of Pb(II) removal by Grewia Asiatica seed: a factorial design approach This study aims to explore the efficiency of an agro waste material for the remediation of Pb(II) contaminated water. A factorial design approach is adopted to optimize removal efficiency and to study the interaction between effective variables. A face-centered Draper-Lin composite design predicted 100% removal efficiency at optimum variables; pH 8, initial concentration of Pb(II) ion 12mg/L, sorbent dose 200mg and agitation time 110 min. Regration coefficient (R2 = 99.9%) of a plot of the predicted versus the observed values and p value (>0.05) confirms the applicability of the predicted model. Langmuir and Dubinin-Radushkevich (D-R) isotherm models were applicable to sorption data with the Langmuir sorption capacity of 21.61±0.78 mg/g. The energy of sorption was found to be 13.62±0.32 kJ/mol expected for ion-exchange or chemisorption nature of sorption process. Characterization of Grewia seed suggested a possible contribution of carboxyl and hydroxyl groups in the process of biosorption. The present study shows that Grewia seeds can be used effectively for the remediation of Pb(II) contaminated water.

Synthesis and characterisation of novel chelating resin for selective preconcentration and trace determination of Pb(II) ions in aqueous samples by innovative microsample injection system coupled flame atomic absorption spectrometry

Expanded polystyrene (EPS) foam waste (white pollutant) was utilised for the synthesis of novel chelating resin i.e. EPS-N = N-α-Benzoin oxime (EPS-N = N-Box). The synthesised resin was characterised by FT-IR spectroscopy, elemental analysis, and thermogravimetric analysis. A selective method for the preconcentration of Pb(II) ions on EPS-N = N-Box resin packed in mini-column was developed. The sorbed Pb(II) ions were eluted with 5.0 mL of 2.0 mol L−1 HCl and determined by microsample injection system coupled flame atomic absorption spectrometry (MIS-FAAS). The average recovery of Pb(II) ions was achieved 95.5% at optimum parameters such as pH 7, resin amount 400 mg, flow rates 1.0 mL min−1 (of eluent) and3.0 mL min−1 (of sample solution). The total saturation capacity of the resin, limit of detection (LOD) and limit of quantification (LOQ) of Pb(II) ions were found to be 30 mg g−1, 0.033 μg L−1 and 0.107 μg L−1, respectively with preconcentration factor of 300. The accuracy, selectivity and validation of the method was checked by analysis of sea water (BCR-403), wastewater (BCR-715) and Tibet soil (NCS DC-78302) as certified reference materials (CRMs). The proposed method was applied successfully for the trace determination of Pb(II) ions in aqueous samples.

Metal-free and azide-free synthesis of 1,2,3-triazoles derivatives

ABSTRACT 1,2,3-Triazoles, significant five-membered ring N-heterocycles, are main structural moieties in well-designed materials, pharmaceutical agents, bioactive products, and synthetic intermediates. In the research of life sciences and pharmaceuticals, by seeing the spacious applications of 1,2,3-triazoles, the progress of metal-free method is exceedingly desirable to evade the heterocyclic product metal contamination. Moreover, on a larger scale, the toxicity and explosiveness of azides makes azides discommode and hard to hold, to synthesize 1,2,3-triazoles. The need to steer the development of the synthesis of 1,2,3-triazoles toward more maintainable synthesis is a pressing issue. There are rare methods to construct 1,2,3-triazoles under azide-free and metal-free environments. These rare methods are compiled in this review. The afford of the collection and compilation of azide-free and metal-free synthesis methodologies of 1,2,3-triazole in single podium is supportive and crucial for synthetic chemist to extend the diversity of the synthesis of 1,2,3-trizoles through green protocol. GRAPHICAL ABSTRACT

Extraction and Determination of Phenolic Acids and Vitamin B of Sieved and Unsieved Wheat Grain by MEKC

An MEKC method has been used to separate m-coumaric acid, ferulic acid, syringic acid, vanillic acid, p-coumaric acid, 4-hydroxybenzoic acid, caffeic acid, gallic acid, and 3,4-Dihydroxy benzoic acid, along with Vitamins B1 and B6 from uncoated fused silica capillary of 60.2 cm total length, 50 cm effective length, and 75 µm id. Optimum separation was achieved with BGE comprised of sodium tetraborate buffer (50 mmolL−1), pH 9.0, Sodium dodecylesulfate (SDS) (10 mmolL−1), and normal propanol (4% v/v), the optimum ratio was 70:20:10 (Borate:SDS:Propanol) with applied voltage of 20 kV at a wavelength of 225 nm. Linear calibration range and limit of detection (LOD) observed for the analytes were in the range 0.1–100 mgL−1 and 0.032–0.068 mgL−1, respectively. Calculated recoveries of analytes by standard addition were in the range 96–102% with RSD of 0.98–1.43%. Phenolic acids: ferulic acid, p-coumaric acid, and syringic acid were identified along with m-coumaric acid which is being reported for the first time from wheat varieties. The amount of phenolic acids in unsieved wheat grain were found to be higher than sieved wheat grains. Acid hydrolysis was found to release vitamin B along with phenolic acids, whereas methnol/water extraction system released phenolic acids only.

Schiff base-functionalised styrofoam resin for preconcentration of metal ions in wastewater and wastewater-irrigated vegetables samples

Polystyrene (PS) was extracted from styrofoam waste and functionalised with schiff base, N,N-bis(salicylidene)cyclohexanediamine (SCHD) through an azo spacer. The resin was characterised and used for preconcentration of Pb(II), Ni(II) and Cd(II) ions prior to their trace determinations by microsample injection system–coupled flame atomic absorption spectrometry (MIS-FAAS). The recoveries of studied metal ions were achieved ≥96.0% with relative standard deviation (RSD) ≤4.5 at optimum parameters: pH 8; resin amount 300 mg; flow rates 3.0 mL min−1 of sample solution; and 2.0 mL min−1 of eluent (2.0 mol L−1 HNO3). The limits of detection (LODs) and limits of quantification (LOQs) were found to be 0.32, 0.23 and 0.21 and 1.10, 0.78 and 0.69 μg L−1, respectively, with preconcentration factors (PFs) of 500, 800 and 1000, respectively. The linear ranges of the method were 1–40, 1–25 and 1–20 μg L−1 for Pb(II), Ni(II) and Cd(II) ions, respectively. The accuracy and validation of the method were evaluated by analysis of certified reference materials (CRMs). The method was successfully applied for preconcentration of studied metal ions in wastewater and wastewater-irrigated vegetable samples.

Multi-variant Sorption Optimization for the Uptake Of Pb(II) Ions by Jamun Seed Waste

In the present study, jamun seed waste has been explored for the removal of Pb(II) ions from aqueous solution. The multi-variant sorption optimization was achieved by the factorial design approach. 99.91% of Pb(II) ions was removed from aqueous solution. The results predicted by the model were in good agreement with the experimental results (the values of R2 and R2adj. were found to be 99.89% and 99.95%, respectively). Langmuir and D-R isotherm studies were carried out to find adsorbent’s capacities (183.9 ± 0.31 mg/g and 184.5 ± 0.16 mg/g respectively), sorption free energy 13.17 ± 0.16 and RL values in the range of 0.05-0.77, suggested the favorable chemical and/or ion exchange nature of the sorption process. The FT-IR study was carried out for unloaded and Pb(II) ions loaded jamun seed, indicated, Pb(II) ions associated with nitrogen and oxygen of jamun seed containing moieties during the adsorption process. The proposed method was successfully validated and applied for the treatment of Pb(II) ions contaminating drinking water.

Chemical Recycling of Expanded Polystyrene Waste: Synthesis of Novel Functional Polystyrene-Hydrazone Surface for Phenol Removal

Expanded polystyrene (EPS) waste was chemically recycled to a novel functional polystyrene-hydrazone (PSH) surface by acetylation of polystyrene (PS) and then condensation with phenyl hydrazine. The synthesized surface was characterized by the FT-IR and elemental analysis. Synthesized novel functional PSH surface was successfully applied for the treatment of phenol-contaminated industrial wastewater by solid-phase extraction. Multivariant sorption optimization was achieved by factorial design approach. 99.93% of phenol was removed from aqueous solution. FT-IR study showed the involvement of nitrogen of hydrazone moiety of synthesized surface for the uptake of phenol through the hydrogen bonding.

Novel Calix(4)arene Network Resin for Cr(VI) ions Remediation: A Response Surface Approach

Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ~100% removal effi ciency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fi tting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal effi ciency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1±2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.

Recycling of styrofoam waste: synthesis, characterization and application of novel phenyl thiosemicarbazone surface

Abstract An attempt has been made to recycle Styrofoam waste to a novel functional polymer, Phenyl thiosemicarbazone surface (PTS). Polystyrene (PS) obtained from Styrofoam waste was acetylated and then condensed to PTS by reacting it with 4-Phenyl-3-thiosemicarbazide ligand and characterized by FT-IR spectroscopy and elemental analysis. Synthesized PTS was applied successfully for the treatment of lead contaminated water by batch extraction method. Sorption variables were optimized (pH 8, adsorbent dose 53mg, initial Pb(II) ion concentration 10mgl-1 and agitation time 90min) by factorial design approach. Lead uptake by PTS was found much sensitive to the pH of Pb(II) ion solution. The maximum removal (99.61%) of Pb(II) ions was achieved at optimum conditions. The Langmuir and D-R isotherm study suggested the monolayer, favorable (RL=0.0001-0.01) and chemisorption (E=20.41±0.12kJmol-1) nature of the adsorption process. The sorption capacity of PTS was found to be 45.25±0.69mgg-1. The FT-IR spectroscopy study showed the involvement of nitrogen and sulphur of thiosemicarbazone moiety of PTS for the uptake of Pb(II) ions by five membered chelate formation.