REMOVAL OF Ni2+ FROM AQUEOUS SOLUTION BY ADSORPTION ONTO TEA WASTE–DERIVED ACTIVATED CARBON

Activated carbon from a locally available and widespread tea waste source was fabricated, characterized and used as an efficient adsorbent for the removal of Ni2+ from aqueous solutions. The response surface methodology (RSM) and central composite design (CCD) were used to investigate the effect of the essential variables including initial concentration, adsorbent dosage and pH solution on the absorption of Ni2+. The order polynomial regression equations–based model has been developed and found to be statistically significant by values of the coefficients of determination (R2) closer than 1.0 and the P–values 0.0001 from analysis of variance (ANOVA). Based on the predicted optimum conditions, actual experiment was employed to obtain the maximum percentage of Ni2+ removal efficiency (96.6 %). There is no doubt that the use of tea waste as abundant raw material for the preparation of activated carbon to remove Ni2+from aqueous solutions by five times with negligible change is a promising way

PREPARATION AND CHARACTERIZATION OF SIO2/POLY(METHYL METHACRYLATE) CORE/SHELL NANOCOMPOSITES VIA RAFT POLYMERIZATION

This article describes the fabrication of SiO2 nanoparticles grafted with poly(methyl methacrylate) (PMMA) via a fascinating reversible addition-fragmentation chain transfer (RAFT) polymerization by adopting “grafting from” approach. The silane coupling agent, S-benzyl S’-trimethoxysilylpropyltrithiocarbonate, was anchored onto SiO2 nanoparticles in a simple procedure using a ligand exchange reaction. RAFT agents-anchored SiO2 nanoparticles were then used for the surface-initiated RAFT polymerization of MMA to fabricate structurally well-defined, core-shell SiO2-g-PMMA nanocomposites. The structure and properties of the as-synthesized nanocomposites were investigated by Fourier Transformed Infrared Spectrophotometry (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM)

CONSTRUCTING POLYSTYRENE BRUSHES ON TIO2 NANOPARTICLES BY IN SITU REVERSIBLE ADDITION FRAGMENTATION CHAIN TRANSFER POLYMERIZATION

This paper presents the preparation of polystyrene functionalized TiO2 nanoparticles using the reversible addition fragmentation chain transfer (RAFT) polymerization. The surface of TiO2 NPs with an average particle size of about 5 nm was modified by S-benzyl S’-trimethoxysilylpropyltrithiocarbonate in order to obtain the RAFT agent functionalized TiO2 NPs (TiO2-RAFT). Subsequently, styrene was radically polymerized through the immobilized RAFT agent on the silica surface, in the presence of 2,2’-azobisisobutylnitrile (AIBN) as an initiator, to achieve the TiO2-g-PS nanocomposite. The characteristics of the as-synthesized nanocomposite were determined using FT-IR, EDX, XPS, TGA, XRD, TEM and SEM analyses

Kinetic modeling of essential oil hydro-distillation from peels of pomelo (Citrus grandis L.) fruit grown in Southern Vietnam

Thorough understanding of kinetics plays a key role in improving existing industrial processes. In this study, we attempted to model the kinetics of the hydro-distillation process that produces essential oil from peels of pomelo (Citrus grandis L.) fruit, which is a product with high economic value and a wide range of applications. We first determined the optimal water-to-material ratio for attaining maximal oil yield. Then, further experimental attempts were carried out at different distillation rates to generate experimental data to fit three kinetic models, namely first-order kinetics model, instantaneous washing, followed by diffusion model and simultaneous washing and diffusion model. Overall, the three models have well described the experimental kinetic data on hydro-distillation (R2> 90%). Of which, the simultaneous washing and diffusion model attaining the R2 of 99.97% was chosen as the most suitable to describe the kinetics of the extraction process. Estimated parameters also shown that the washing stage occurs more rapidly than the later, diffusion stage. GC-MS results showed that the obtained oil sample was characterized by the dominance of the D-Limonene compound (97.873%)

Adsorptive removal of Pb (II) using exfoliated graphite adsorbent:influence of experimental conditions and magnetic CoFe2O4 decoration

The worm-like exfoliated graphite (EG) based adsorbents prepared from low-cost natural graphite flakes via facile synthesis processes have been found to be efficient adsorbents when it comes to removing Pb (II) from aqueous solution. EG was fabricated by chemical intercalation and microwave assisted exfoliation. Furthermore, the magnetic exfoliated graphite (MEG) was developed by incorporating CoFe2O4 particles into the EG layers using the citric acid based sol-gel technique. Adsorption behaviour of Pb (II) on the as-prepared adsorbents was investigated by taking several experimental conditions into consideration such as contact time, initial concentration, adsorbent dosage, and pH value. The results with initial neutral pH indicated that the adsorption isotherms for Pb (II) on the EG and MEG were well consistent with the Langmuir isotherm model revealing the maximum adsorption capacity of 106 mg/g and 68 mg/g for EG and MEG, respectively. The adsorption kinetics of Pb (II) was found to adhere to the pseudo-second-order kinetic model. The chemical interaction between ? electrons on graphite sheets and Pb (II) ions was suggested to play an essential role in the adsorption mechanism. The introduction of magnetic CoFe2O4 to the EG was found to induce the shift of optimal pH value to a more basic condition. The characterization of the adsorbents was performed using relevant analysis techniques such as Scanning electron microscope (SEM), X–ray powder diffraction (XRD), vibrating-sample magnetometer (VSM), and Fourier-transform infrared (FTIR). The results of this work suggest a high possibility for application of the as-prepared modified graphite to remove hazardous substances in practical wastewater treatment systems. ABSTRAK:  Penyerap Pengelupas Grafit (EG) yang berupa seperti cacing dihasilkan dari grafit semulajadi yang murah melalui proses sintesis serpihan, ia juga merupakan penyerap yang bagus dalam mengasingkan Pb (II) daripada larutan akues. EG direka dengan tindak balas interkalasi kimia dan pengelupasan melalui gelombang mikro. Tambahan, pengelupas grafit magnet (MEG) telah dihasilkan dengan memasukkan zarah CoFe2O4 ke dalam lapisan EG menggunakan teknik sol-gel yang berasaskan asid sitrik. Tindak balas penyerapan Pb (II) pada penyerap yang disiapkan ini, dikaji dengan mengambil kira beberapa keadaan eksperimen seperti waktu disentuh, konsentrasi awal, dos penyerap dan nilai pH.  Hasil keputusan pH neutral awal menunjukkan bahawa isoterm penyerapan bagi Pb (II) pada EG dan MEG adalah konsisten dengan model isoterm Langmuir. Ini menunjukkan kapasiti penyerapan maksimum 106 mg/g dan 68 mg/g bagi EG dan MEG, masing-masing. Penyerapan kinetik Pb (II) didapati mematuhi model kinetik pesudo-order-kedua. Interaksi kimia antara elektron ? pada helaian grafit dan ion Pb (II) memainkan peranan penting dalam mekanisme penyerapan. Pengenalan magnet CoFe2O4 kepada EG didapati telah mengubah nilai pH optimum kepada keadaan asal. Pengelasan penyerapan dilakukan menggunakan teknik analisis yang relevan seperti Mikroskop Elektron Pengimbasan (SEM), Difraksi Serbuk sinar-X (XRD), Magnetometer Sampel-Getaran (VSM) dan Inframerah Perubahan-Fourier (FTIR). Hasil kerja ini mencadangkan kemungkinan besar bagi penggunaan grafit ubah suai yang disediakan bagi membuang bahan berbahaya dalam sistem rawatan air sisa praktikal

Adsorption of ciprofloxacin using composite Film from PVA, agarose and maltodextrin

Rintangan antibiotik ialah salah satu masalah yang paling membimbangkan hari ini. Oleh itu, membran komposit telah digunakan secara meluas untuk penyingkiran antibiotik daripada air. Filem PVA/Agarosa/Maltodekstrin telah disintesis dengan tuangan dengan pelbagai nisbah komponen. Ia dinilai untuk ciri melalui kelembapan, keterlarutan, pengembangan dan keputusan BET. Keputusan menunjukkan bahawa filem PVA/Agarosa/Maltodekstrin mempamerkan daya maju terbaik dalam persekitaran akuatik melalui keterlarutan rendah (68.88% ± 0.03), bengkak tinggi (431.77% ± 5.89) dan isi padu liang (0.034969 cm³/g). Kapasiti penjerapan PVA/Agarosa/Maltodekstrin telah diuji untuk beberapa antibiotik seperti Ciprofloksacin, Tetracycline, Oxy-Tetracycline dan Chloramphenicol. Keputusan menunjukkan bahawa Ciprofloksacin telah dikeluarkan oleh filem PVA/Agarosa/Maltodekstrin lebih baik daripada antibiotik lain. Penjerapan antibiotik tertinggi diperoleh pada 20 minit, suhu 30 °C, dos 2 g/L, pH 6 dan kepekatan antibiotik 40 mg/L. Penjerapan Ciprofloksacin telah diramalkan melalui model kinetik dan isoterma penjerapan. Keserasian kinetik Pseudo First Order dan isoterma Dubinin-Radushkevich telah menunjukkan bahawa penjerapan berlaku mengikut mekanisme penjerapan fizikal dengan interaksi elektrostatik pada permukaan bahan. Kapasiti penjerapan maksimum direkodkan pada 4.48 mg/g berdasarkan isoterma Dubinin-Radushkevich

THÀNH PHẦN HÓA HỌC VÀ HOẠT TÍNH KHÁNG VI SINH VẬT GÂY BỆNH CỦA TINH DẦU TỪ VỎ BƯỞI DA XANH (Citrus maxima (Burm.) Merr.)

Pomelo is a Vietnam’s plant species with high nutritional and economic value. Besides, pomelo essential oil contains numerous compounds with high biological activity. The essential oil is extracted by using steam distillation, and its chemical composition is determined by means of GC-MS. The major components are limonene (91.19%), b-myrcene (2.92%), a-phellandrene (1.98%), and a-pinene (1.19%). The antimicrobial activity of essential oils is tested against pathogenic Gram-positive bacteria (Bacillus cereus, Staphylococcus aureus), Gram-negative bacteria (Escherichia coli), and Aspergillus flavus at different concentrations with the agar well diffusion method. This essential oil is active against B. cereus, S. aureus, and E. coli with inhibition diameter zones at 8.3–11.3, 10.3–18.7, and 9.0–11.7 mm, respectively, and inhibits A. flavus mold with 18.9–65.0% efficiency.Bưởi là loài cây không chỉ có giá trị cao về mặt dinh dưỡng mà còn có giá trị cao về mặt kinh tế và được trồng phổ biến ở Việt Nam. Ngoài ra, tinh dầu bưởi chứa nhiều hợp chất có hoạt tính sinh học cao. Tinh dầu bưởi được chiết xuất bằng phương pháp chưng cất lôi cuốn hơi nước và thành phần hóa học được phân tích bằng phương pháp GC-MS. Thành phần chính của tinh dầu gồm limonene (91,19%), b-myrcene (2,92%), a-phellandrene (1,98%) và a-pinene (1,19%). Hoạt tính kháng vi sinh vật của tinh dầu được khảo sát với vi khuẩn Gram dương (Bacillus cereus, Staphylococcus aureus), Gram âm (Escherichia coli) và nấm mốc Aspergillus flavus ở nồng độ 5, 10, 25 và 50% bằng phương pháp khuếch tán giếng thạch. Tinh dầu có khả năng kháng B. cereus, S. aureus và E. coli với đường kính vòng kháng khuẩn lần lượt là 8,3–11,3, 10,3–18,7 và 9,0–11,7 mm và ức chế sự phát triển của A. flavus (18,9–65,0%)