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2 2023

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Catalytic Ozonation of Ponceau 4R Using Multifunctional Magnetic Biochar Prepared from Rubber Seed Shell

Nguyen Hung Minh, Truong Tram Thi Bao, Nguyen Hong-Hue Thi, Tran Phong Thanh, Tran-Thuy Tuyet-Mai, Nguyen Long Quang, Nguyen Dung Van

Journal of Ecological Engineering

2023

Vol. 24, nr 12

143--151

Herein, abundant and underutilized rubber seed shell (RSS) was valorized for one-pot production of multifunctional magnetic biochar (MBC) through one-pot FeCl3 activation. Fe3O4 and Fe0 crystals were formed in MBC, providing a saturation magnetization of 6.83 emu/g. In addition, the material had a specific surface area of 378 m2/g and a total pore volume of 0.22 cm3/g. MBC was subsequently explored for catalytic ozonation of Ponceau 4R (P4R). As a result, MBC enhanced P4R ozonation in a broad pH range of 3.0–9.0. At pH 5.8, the pseudo-first-order rate constant of P4R decolorization with MBC improved by 50% compared to that without MBC. Summarily, RSS-derived MBC is a potential catalyst for enhanced ozonation of Ponceau 4R thanks to its low cost, eco-friendliness, relative effectiveness, and magnetic separability.

Studying the thermo-gas-dynamic process in a muzzle brake compensator

Nguyen Dung Van, Bui Viet Quy, Nguyen Dung Thai, Uong Quyen Si, Truong Hieu Tu

Archive of Mechanical Engineering

2023

LXX, nr 2

311--328

To reduce the recoil and improve the stability of small arms, a muzzle brake compensator is attached to the muzzle of the barrel. This device uses the kinetic energy of the powder gas escaping from the bore after the bullet is fired. In this paper, the authors present the determination of the thermo-gas-dynamic model of the operation of a muzzle brake compensator and an example of calculating this type of muzzle device for the AK assault rifle using 7.62x39 mm ammunition. The results of the calculation allowed for obtaining the parameters of the powder gas flow in the process of flowing out of the muzzle device, as well as the change in the momentum of the powder gas's impact on the muzzle device. The model proposed in the article provides the basis for a quantitative evaluation of the effectiveness of using the muzzle device in stabilizing infantry weapons when firing.