Shaikh Asrof Ali

15 wt % HCl used in oil and gas acidizing operations causes severe corrosion to operational pipelines and tubing. In this work, a pyrrolidine- and quaternary ammonium salt-based cyclocopolymer (PCP) has been synthesized as an efficient corrosion inhibitor for mild steel under oil- and gas-acidizing conditions. PCP was characterized by 1H and 13C NMR, FT-IR, and TGA. PCP, with thermal stability up to ≈300 °C, retarded corrosion of mild steel in 15 wt % HCl by ≈90% at 100 ppm at 298 K, as confirmed via weight loss (WL), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and linear polarization resistance (LPR) techniques. The adsorption of PCP onto mild steel followed the Langmuir adsorption isotherm. ΔGads° values (≈42 kJ mol–1) calculated using surface coverage (θ) data indicated a mixed physico-chemisorption mode of adsorption with chemisorption predominance, further supported via detailed discussion on kinetic and activation parameters (Ea, ΔH‡, and ΔS‡). PDP study demonstrated that PCP acted as a mixed-type inhibitor with anodic predominance. SEM-EDX and XPS studies provided strong evidence for PCP adsorption onto the mild steel surface. Antibacterial studies showed that PCP, at concentrations up to 100 ppm, did not interfere with E. coli growth up to 12 h. Computational toxicity prediction, including several organ toxicity and toxicity end points, proved PCP to be much less toxic (LD50 775 mg kg–1) than efficient small-molecule inhibitors. A reasonable explanation for the mechanism of inhibition has been proposed based on the experimental and DFT findings.

This research focuses on synthesizing a novel antiscalant and exploring the inhibition of CaSO₄ and CaCO₃ scaling in reverse osmosis desalination technology. The antiscalant bearing residues of aspartic and maleic acid (MA) has been synthesized via alternate cyclopolymerization of N,N-diallylaspartic acid [(H₂CCH–CH₂)₂NH⁺CH­(CO₂ ^–)­CH₂CO₂H] and MA. The performance of the antiscalant and several commercial ones was evaluated against supersaturated CaSO₄ and CaCO₃ solutions. At a 2.5 ppm concentration, the antiscalant imparted percent scale inhibition (PSI) of ≈100% for CaSO₄ until 820 min [i.e., induction time (IT) after which scaling starts]. The superior performance of the antiscalant was ascertained at 0.5 and 1 ppm concentrations at 40 °C, where it showed ITs of 40 and 60 min, respectively, which are sufficient to mitigate scaling during the 15 min residence time of the reject brine in the osmosis chamber. The antiscalant was also examined for the mitigation of CaCO₃ scaling.

A new diallyl amine salt monomer (I) bearing Li⁺ chelating 12-Crown-4 ether motifs [(H₂C = CHCH₂)₂NH⁺CH₂-(12-C-4) Cl⁻] was synthesized. Monomer (I) under free radical cyclopolymerization and alternate copolymerization with SO₂ afforded homo (II) and copolymer (III) in good yields. Terpolymerization of I, SO₂, and a cross-linker tetraallylhexane-1,6-diammonium chloride (IV) gave cross-linked resin V, which has been utilized as a scavenger for lithium ions from aqueous samples via the liquid‒solid technique. Optimizing a method involves adjusting multiple variables, such as pH, Li⁺ concentration, and resin dose, to achieve the best possible results. The adsorption capacity was determined using inductively coupled plasma-optical emission spectroscopy (ICP‒OES). The lithium removal study was conducted at concentrations ranging from 20 to 100 ppm. Resin V adsorbs lithium ions rapidly with excellent efficiency following second-order kinetics and fitting the Temkin and Langmuir adsorption isotherms. The resin demonstrated remarkable selectivity in adsorbing Li⁺ from its binary mixtures Li⁺/Na⁺ and Li⁺/K⁺.

This study entails the syntheses of a homopolymer, poly(diallylammonium chloride) (3), and copolymers (8a–c) containing hydrophilic/hydrophobic pendants and their role in mitigating mild steel in aggressive 20% formic acid, a type of corrosion that is not frequently discussed in the literature. The synthesized homopolymer and copolymers were characterized by FTIR, NMR, viscometry, and TGA. Inhibitor 8b was found to be the most potent, with 81.8% inhibition efficiency (IE) registered via the potentiodynamic polarization method for 100 ppm of inhibitor concentration at 30 °C. Inhibitor 8b, mixed with 2 mmol KI, showed more than 90% IE for a meager 1 ppm inhibitor concentration. For a synergism of 50 ppm inhibitor and 2 mmol KI, the IE reached a high value of 99.1%. The synergism was so good that it helped the inhibitor retain ∼100% of its original IE even after a 24 h weight loss study at 60 °C. The adsorption isotherm study showed that 8b followed the Langmuir adsorption isotherm and adsorbed via chemisorption. A very high value (2.48 × 10⁵ L mol⁻¹) of the equilibrium adsorption constant (K_ads) indicated strong adsorption. XPS and SEM surface studies provided evidence of the inhibitor found on the metal surface. Some toxicological parameters, such as LC50, bioaccumulation factor, and developmental toxicity, have been measured computationally. A brief mechanistic insight into how the inhibitors functioned has been offered along with the DFT study.

Polyvinylidene fluoride (PVDF) membrane-based systems for treating oily wastewater are prone to fouling. Herein, we introduced a novel mussel-inspired cationic amphiphilic terpolymer consisting of monomers N,N-diallyldimethylammonium chloride (DADMAC), N,N-diallyltetradecan-1-ammonium chloride (DTDAC), and mussel-inspired N,N-diallyldopamine hydrochloride (DADAHC) to improve the performance and characteristics of the PVDF membranes for oil-in-water emulsion separations. The cationic terpolymer, poly(DADMAC-co-DTDAC-co-DADAHC), shortened as PDDD, was synthesized in excellent yields via free radical polymerization and has good compatibility with the PVDF owing to the presence of hydrophobic long alkyl chains in DTDAC. The presence of dopamine motifs helps stabilize the PDDD-PVDF membrane by chelating with Fe³⁺ ions. The water contact angle on the PDDD-incorporated PVDF membranes was reduced from 87.6 to 54.6°, demonstrating improved hydrophilicity than pristine PVDF (M-0). The incorporation of PDDD into the PVDF improved the separation efficiencies of the membrane, which reached up to 99% while treating the oil-in-water emulsions. Incorporating PDDD into PVDF has significantly enhanced the anti-fouling characteristics of the membranes, which are indicated by their remarkable flux recovery ratio (FRR) (up to 92%). The hydrophobic and hydrophilic groups worked synergetically to enhance the performance of the fabricated membrane.

The present study describes the synthesis and characterization of a poly(methyldiallylammonium chloride)-based surfactant containing bis-cationic motifs (9) through a series of reactions. The synthesized polymer 9 was characterized using FTIR and NMR spectroscopy and tested as a corrosion inhibitor for C1018 carbon steel (C1018 CS) in 1 M HCl using gravimetric weight loss, electrochemical, computational, and surface measurements. Polymer 9 serves as an excellent corrosion inhibitor and manifests 78.05%, 86.59%, and 92.68% inhibition efficiency values at 2, 5, and 50 ppm concentrations, respectively. Chemical analyses suggest that the inhibition efficiency of polymer 9 increases with an increase in the concentration and decreases with an increase in the temperature. The results indicate that polymer 9 becomes effective through adsorbing at the interface of C1018 CS following the Langmuir adsorption isotherm model. The outcomes of a polarization study reveal that polymer 9 behaves as a mixed-type inhibitor. Polymer 9 becomes effective by blocking the active sites responsible for the corrosion. The increase in the charge transfer resistance in the presence of polymer 9 also supported the above conclusion. The corrosion mitigation ability of polymer 9 through the adsorption mode was also demonstrated using scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) based surface investigations. Lastly, the mechanism of the adsorption of polymer 9 on the metallic surface was proposed based on the outcomes of DFT studies. A good agreement in the results of various experiments was observed.

This article reviews the synthesis of polyzwitterions (PZs) (poly‐carboxybetaines, ‐phosphonobetaines, and ‐sulfobetaines) having multiple pH‐responsive centers. The synthesis follows the Butler cyclopolymerization protocol involving a multitude of diallylammonium salts and their copolymerization with SO₂ and maleic acid. The PZs have been transformed into cationic‐, anionic‐polyelectrolytes, and polyampholytes under the influence of pH. Particular attention is given to the application of these polymers as antiscalants, mild steel corrosion inhibitors, components in constructing Aqueous Two‐Phase Systems (ATPSs), and membrane modifiers. The ATPSs could be used to separate various biomolecules, including proteins. Many amphiphilic polymers incorporating a few mol % hydrophobic monomers have shown enhanced viscosities and could be suitable for applications in oil fields. The progress of applying Butler cyclopolymerization in reversible addition‐fragmentation chain transfer (RAFT) chemistry has been discussed. Future works are expected to focus on RAFT cyclopolymerization to construct block copolymers.