Preparation of metal adsorbent from poly(methyl acrylate)-grafted-cassava starch via gamma irradiation

Evaluation of the self-assembled functional PPFS-P-AM composite for treating oilfield sewage

Oilfield sewage has a complex composition with large amounts of emulsified oils, polymers and surfactants. Efficient coagulants are required to purify such sewage to meet emissions standards. In this study, oxidized FeSO₄·7H₂O and NaHCO₃were condensed by basic titration and polyferric sulfate phosphate (PPFS) was prepared by the addition of NaH₂PO₄·2H₂O to improve its charge and stability. In addition, by adding modified palygorskite and cationic amylum, a functional polyferric sulfate phosphate, palygorskite and cationic amylum copolymer (PPFS-P-AM) composite coagulant was synthesized through self-assembly, and then used to treat oilfield sewage. The characteristic functional groups and crystal forms of the coagulant were characterized by FTIR and XRD. The zeta potential and radius of gyration (R_h) indicate that the introduction of palygorskite and cationic amylum enhance the charge neutralization and bridging adsorption abilities, respectively. The optimal dosage of cationic amylum is 5% in 80 mg·L^-1 PPFS-P-AM, which provides turbidity and oil removal rates of 98% and 94%, respectively. Observation by SEM shows that the micro-morphology of PPFS-P-AM flocs has adendritic distribution with a reticular macromolecular structure that provides good sweeping performance during the sedimentation process. Finally, an analysis of its properties and performance reveals the mechanism by which PPFS-P-AM coagulates oilfield sewage. PPFS-P-AM provides better coagulation than the other studied coagulants via the synergistic effects of reinforced charge neutralization, bridging adsorption and sweeping.

On the Use of Starch in Emulsion Polymerizations

The substitution of petroleum-based synthetic polymers in latex formulations with sustainable and/or bio-based sources has increasingly been a focus of both academic and industrial research. Emulsion polymerization already provides a more sustainable way to produce polymers for coatings and adhesives, because it is a water-based process. It can be made even more attractive as a green alternative with the addition of starch, a renewable material that has proven to be extremely useful as a filler, stabilizer, property modifier and macromer. This work provides a critical review of attempts to modify and incorporate various types of starch in emulsion polymerizations. This review focusses on the method of initiation, grafting mechanisms, starch feeding strategies and the characterization methods. It provides a needed guide for those looking to modify starch in an emulsion polymerization to achieve a target grafting performance or to incorporate starch in latex formulations for the replacement of synthetic polymers.

Biodegradable glucose and glucosamine grafted polyacrylamide/graphite composites for the removal of acid violet 17 from an aqueous solution

In this work, the structural characterization and adsorption behavior of glucose and glucosamine grafted polyacrylamide/graphite composites (denoted as Gu-g-PAM/graphite and GA-g-PAM/graphite) were investigated. The grafted polymers were characterized by using Fourier transform infrared (FT-IR) spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR and N2 sorption studies. The adsorption behavior of grafted polymers was compared by varying parameters such as pH, initial dye concentration, agitation time, adsorbent dose and temperature. The results showed that GA-g-PAM/graphite composite was an effective adsorbent for the uptake of acid violet 17 (Av-17) from an aqueous solution. The superior adsorption behavior was attributed to the presence of -NH2 and -OH groups in GA-g-PAM/graphite. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms were used to describe the adsorption isotherm. The adsorption isotherm of the adsorbents fitted well with the Langmuir model with the maximum adsorption capacity (qo) of 78.13 mg/g for GA-g-PAM/graphite. The efficiency of adsorption with time was described using pseudo first-order, pseudo second-order and intra particle diffusion kinetic models. The kinetic study revealed that the adsorption equilibrium was attained within 50 min. The thermodynamic analysis stated that the adsorption of dye is spontaneous, physical and endothermic in nature. Desorption results revealed that all the adsorbents exhibit excellent stability and remarkable regeneration ability.

Sweet potato starch residue as starting material to prepare polyacrylonitrile adsorbent via SI-SET-LRP

Sweet potato starch residue (SPSR) was used as starting material to prepare an eco-friendly adsorbent. SPSR was modified by bromoacetyl bromide to obtain a macroinitiator for surface-initiated single electron transfer-living radical polymerization (SI-SET-LRP) of acrylonitrile (AN) catalyzed by La(0)/hexamethylenetetramine (HMTA) in N,N-dimethylformamide (DMF) in the presence of ascorbic acid (VC). The amidoxime (AO) adsorbent was prepared by the reaction of the graft copolymer bromoactylated sweet potato starch (BSPS)/polyacrylonitrile (BSPS-g-PAN) with hydroxylamine. The maximum adsorption capacity for Hg(II) was 4.03 mmol·g(-1). This simple method provided a novel approach to recycle and reuse agricultural residues for controlling heavy metal pollution.