Journal of Polymers and the Environment

A series of polyaniline-modified TiO2 photo-catalysts (TiO2@PANI) were prepared via an in-situ polymerization of aniline onto TiO2 nanoparticles. The Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA) confirmed that the polyaniline (PANI) successfully grafted on the TiO2 NPs. The X-ray diffraction (XRD) patterns showed that the crystalline structure of the TiO2 did not change during the preparation of PANI. Photodegradable nanocomposites were prepared by embedding the photocatalysts into the commercial poly(vinyl chloride) (PVC) samples. The nanocomposite films were compared against pure PVC and PVC-TiO2 films for their photodegradation performances. The photocatalytic activity of the TiO2@PANI catalysts improved with an increase in the inorganic/organic molar ratio. With the TiO2 aniline molar ratio of 10, the PVC-TiO2@PANI nanocomposite film lost about 67% of its weight after 720 h irradiation under UV. Meanwhile, the pure PVC and PVC-TiO2 control films lost about 12 and 45% of their initial weights, respectively. Results showed that the rate at which the PVC is photodegraded can be controlled by the amount of the TiO2 NPs as well as the initial TiO2 aniline molar ratio. The SEM micrograms indicated a rougher and more porous surface for the irradiated PVC-TiO2@PANI compared with controls.

Có một nhu cầu cấp thiết cho việc phát triển các công thức phân bón nitơ (N) bền vững và có hiệu quả sử dụng cao để đảm bảo an ninh lương thực và giảm thiểu biến đổi khí hậu. Gần đây, công nghệ nano đã cho thấy tiềm năng đóng góp vào sản xuất hóa chất nông nghiệp bền vững thông qua việc bọc các vật liệu nano hữu cơ và vô cơ. Trong nghiên cứu này, chúng tôi đã khám phá việc sử dụng các hạt nano encapsulated nickel với các lớp bọc phân hủy sinh học khác nhau như: tinh bột, polyvinyl alcohol (PVA), gum arabica, gelatin, mật mía và sáp paraffin (PW) để cải thiện các tính chất vật lý của phân bón N thông thường trong hệ thống cây trồng đất. Các kết quả cho thấy việc bọc hạt ure bằng các hạt nano encapsulated nickel đã làm tăng đáng kể tính khả dụng của N và do đó năng suất chất khô của cỏ Rhode. Các vật liệu bọc làm giảm độ hòa tan và tăng cường khả năng chịu lực của các hạt. Phương pháp điều trị UC-5 chứa tinh bột, PVA, mật mía, PW và Ni-NPs cho kết quả tốt nhất về tỷ lệ giải phóng (77,96% lượng ure được giải phóng sau 120 phút so với 100% lượng ure được giải phóng cho hạt không bọc), độ cứng nén (70 ± 0,27 N) và năng suất chất khô của cỏ Rhode (58,55 g/pot). Các kết quả cho thấy rằng phương pháp điều trị UC-5 cải thiện đáng kể nitơ khoáng trong đất so với các hạt không bọc và ure chỉ bọc bằng NiO-NPs. Do đó, công thức này sẽ được xem xét để cải thiện khả năng hấp thụ N của cây trồng dưới nông nghiệp bền vững và sạch.

The present study describes the treatment of sugar industry waste water and its use as a potential low cost substrate for production of bioplastic by Bacillus subtilis NG05. The B. subtilis NG05 grow at the rate of 0.14 g h−1 L−1 of production media used and accumulate the 50.1 % of poly β-hydroxybutyrate (PHB). The phase contrast microscopy revealed the presence of PHB granules in B. subtilis NG05 which was further confirmed by Fourier transform infrared spectroscopy and 1H-nuclear magnetic resonance. The polymer was further analysed by differential scanning calorimetry. PHB production yield was achieved up to 4.991 g L−1 with Sugar industry waste water as sole nutrient source. Thus the process provided dual benefits of conversion of a waste material into value added product, PHB and waste management.

In this work, the synthesis of biopolyols derived from castor oil and different glycerols was performed by chemical glycerolysis with sodium hydroxide as catalyst at 225 °C. The biopolyol obtained from high purity glycerol led to predominantly MAG formation, whereas the biopolyol produced using crude glycerol, byproduct from biodiesel industry, resulted in higher DAG, TAG and FFA content due to the higher amount of water. Both biopolyols were employed for the synthesis of polyurethane (PU) foams by bulk polymerization using methylene diphenyl diisocyanate (MDI) at different NCO:OH ratios. The foams were evaluated by apparent density, insoluble fraction, Fourier transform infrared spectroscopy, scanning electron microscope and thermogravimetric analysis. The results showed that crude glycerol provided PU foams as much as commercial glycerol, however the characteristics may be different, mainly due to the presence of water in the reaction medium.

The accumulation of organophosphorus pesticide residues in aqueous media due to their highly recalcitrant nature is causing increasing human health and ecosystem concerns. In this study, sponge composites were fabricated with five different ratios of chitosan (CS) and sodium alginate (SA) for the removal of malathion from aqueous media. The structural and morphological features of these nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller. The CS-SA with a ratio of 1:1.5% was selected as the best adsorbent. The process optimization was performed using the response surface methodology based on Box–Behnken design as a function of the pH (4–10), malathion concentration (5–15 mg L−1), contact time (10–20 min), and adsorbent dosage (0.1–0.2 g). The maximum removal was obtained at 97.56% under the optimum conditions of 7, 15 min, 10 mg L−1, and 0.15 g for the pH, contact time, malathion concentration, and adsorbent dosage, respectively. Langmuir and Freundlich adsorption isotherm models were surveyed and the data were fitted well with the Langmuir isotherm model (R2 = 0.9993). The maximum adsorption capacity (qmax) was found to be 52.08 mg g−1, indicating good potential of CS-SA in the adsorption of malathion. The adsorption kinetics was investigated with the pseudo-first-order and pseudo-second-order (PSO) models. The PSO with R2 = 0.9999 showed the best fit to the experimental data. The implementation of this study reveals that CS-SA is a potential adsorbent for application in the removal of pesticides from aqueous solutions.

Many controversial issues have recently been associated with plasticized poly(vinyl chloride) (pPVC) used in building applications, mainly for flooring. One of them has to do with the health impact of some plasticizers and thermal stabilizers based on heavy metal compounds. Recent advances in the synthesis of polyolefins based on metallocene catalysts can yield similar flexibility for formulations as is now available for those based on pPVC. Polyolefin copolymers are considered to be possible replacements for pPVC. The soil burial test has demonstrated that highly filled polyolefin elastomer formulations having a significant percentage of post-consumer polyolefins (up to 60% in laboratory conditions) have interesting properties from the biodegradation point of view. They are more resistant to microorganisms’ attack than plasticized flooring formulations based on PVC that are currently used, even in a very harsh environment as soil, where complex mixtures of microorganisms are present. The effect of microorganisms’ attack after soil burial was evaluated by visual examination, weight loss, water absorption and changes in mechanical properties.

In this study, we investigated the preparation of cationic/anionic chitin nanofiber (CNF) composite materials by electrostatic interaction. An aqueous dispersion of amidinium CNF was prepared by a top-down approach, and a maleylated CNF film was obtained by a bottom-up approach from a chitin ion gel in an ionic liquid with subsequent maleylation on the CNFs. The resulting film was dispersed in ammonia (aq), which was then mixed with the aqueous cationic CNF dispersion to give the composite film. The composition of the two CNFs was evaluated by scanning electron microscopy and X-ray diffraction measurements. Tensile testing results indicated that the mechanical properties of the composites were enhanced with increasing degrees of substitution of the cationic and anionic groups on CNFs, and also when the molar ratio of these groups approached 1:1. The dissociation of the two kinds of CNFs by alkaline treatment of the composite film was achieved, suggesting the presence of an electrostatic interaction among the interactions between them.

The tensile and combustion properties of polypropylene/polyolyaltha olefin composites filled with intumescent flame retardant (IFR) and nanometer calcium carbonate (nano-CaCO3) were measured. It was found that the values of the Young’s modulus of the composites increased almost linearly, while the values of the tensile yield strength and tensile fracture strength of the composites decreased with increasing the IFR weight fraction; the values of the elongation at break of the composites decreased quickly when the IFR weight fraction was lower than 10 wt%, and then varied slightly when the IFR weight fraction was higher than 10 wt%. Moreover, the morphology of the specimens after combustion was observed and the frame retardant mechanisms of the composites were discussed.

Vi hạt polyhydroxybutyrate-co-hydroxyvalerate (PHBV-MS) đã được chuẩn bị như một hệ thống phân phối cho thuốc diệt cỏ atrazine (ATZ). Việc định danh hệ thống bao gồm việc khảo sát các tính chất giải phóng in vitro và độc tính gen. Đường kính hạt ATZ − PHBV-MS cho thấy dải kích thước từ 1–13 μm. Phân tích nhiệt vi sai cho thấy rằng ATZ được liên kết với các vi hạt PHBV. Các hồ sơ giải phóng cho thấy hành vi giải phóng khác nhau giữa thuốc diệt cỏ nguyên chất trong dung dịch so với dung dịch chứa ATZ được nạp vào PHBV-MS. Phân tích mô hình Korsmeyer–Peppas cho thấy rằng việc giải phóng atrazine từ các vi hạt xảy ra thông qua sự kết hợp giữa khuếch tán qua ma trận và khuếch tán một phần qua các lỗ chứa đầy nước của các vi hạt PHBV. Kết quả thử nghiệm với Lactuca sativa cho thấy rằng độc tính gen của PHBV-MP chứa ATZ đã giảm so với ATZ một mình. Các kết quả chứng minh một hệ thống giải phóng thuốc diệt cỏ phân hủy sinh học khả thi sử dụng atrazine cho các mục đích hóa chất nông nghiệp.