Issues: Kỹ thuật và Công nghệ cho Phát triển bền vững Vol 34.1 (03/2024)
1. Bioconversion of shrimp by-product into carotenoids using pigmented yeast Sporidiobolus pararoseus Q

Tuan Anh Pham*, Hoang Lan Nghiem, Kim Anh To

Chitin, a natural polysaccharide, is the second most abundant biopolymer in the world after cellulose. It consists of N-acetylglucosamine (NAG) monomers and finds widespread applications in the food, cosmetics, and pharmaceutical industries. In this study, we selected pigmented yeast strains to synthesize carotenoids from NAG and optimized the conditions for carotenoids production. The results demonstrated that the selected strain Sporidiobolus pararoseus Q could accumulate β-carotene and carotenoids, reaching 518.84 µg/g dry biomass and 595.48 µg/g dry biomass, respectively, after 96 hours of fermentation with 30 g/L NAG at pH 5. The two-step fermentation with 80 g/L of glucose then 50 g/L of NAG increased 41% and 35% the carotenoids and β-carotene, achieved 786.69 µg/g and 632.19 µg/g, respectively. The ability to use NAG as the source for carotenoids production not only adds value for shrimp by-product but also contributes to environmental pollution control.

Article Code:23059

# N-acetylglucosamine, carotenoid, β-carotene, Sporidiobolus pararoseus

Page: 1-8

Field: Biotechnology and Food Technology
2. Identifying the Key Parameters in Mathematical Model to Simulate the Main Nutrients Transformation Process in Vietnamese Catfish (pangasianodon hypophthalmus) Ponds

Le Xuan Thinh*, Dang Xuan Hien, Tran Van Nhan

Pangasius farming is a process that involves putting a large amount of material into the pond but then only harvesting a small amount of farmed fish, the rest is waste put into the aquatic environment. Pangasius farming can lead to water pollution, the main reason for the deterioration of the water environment in the rivers and canals of the Pangasius farming area. Establishing a mathematical model to simulate the nutrient transformation processes in the pond is necessary. This study aims to set up a mathematical model to simulate the change in the composition of major nutrients in Pangasius ponds to determine the key parameters that affect the model and maximize the culture regime and help improve fish quality and minimize environmental impact. The results have shown that model output data after calibration are relatively close to reality and the key parameters of the model were defined with value as: VPsettling = 0.5; 0.4, FBMPOC(i) = 0.7, KrefrespDOC = 0.01, kfo = 0.493, kfn = 0.025, Ψ(i) = 0.65, nitrifmax = 0.85, kfp = 0.001277, Kreaeration = 2.4.

Article Code:23043

# Pangasius, modeling, nutrient, sensitive analysis, calibration

Page: 9-18

Field: Environmental Science and Technology
3. Investigation of thermal decomposition and thermal oxidative degradation of a composite of cellulose nanofibers and deproteinized natural rubber grafted methyl methacrylate

Nguyen Thi Quynh, Nguyen Thi Ngoc, Le Quang Dien, Nguyen Thu Ha, Tran Thi Thuy, Nguyen Ngoc Mai*

Natural rubber (NR) is a polymer that has many applications in daily life. However, the traditional rubber industry relies heavily on petroleum-based materials, causing environmental pollution problems. Therefore, to reduce environmental challenges, products created from NR are combined with ecologically safe chemicals and natural fillers such as cellulose nanofibers (CNF). This study presents the effect of CNF on the thermal properties of novel composites made from CNF and deproteinized natural rubber grafted methyl methacrylate (DPNR-g-MMA) under air and nitrogen atmosphere. Graft copolymerization of MMA onto DPNR to produce DPNR-g-PMMA was performed in the latex phase. The CNF/DPNR-g-PMMA composite was created by dispersing CNF in DPNR-g-PMMA at concentrations of 0.5%, 1%, and 1.5% using ultrasonic waves. DPNR-g-PMMA was employed as the composite's matrix and CNF served as its reinforcing phase. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (1H NMR) were used to confirm the success of the graft copolymerization. The thermal properties of materials were studied by Thermalgravimetric analysis (TGA) and Differential scanning calorimetry (DSC). In which, the thermal stability of composites was examined via TGA under air and nitrogen atmosphere. The obtained data illustrate that, in comparison to DPNR and DPNR-g-PMMA, thermal stability increases for all CNF/DPNR-g-PMMA composites, especially at CNF concentrations of 1%. After reinforcing CNF to DPNR-g-PMMA, the decomposition temperatures of CNF/DPNR-g-PMMA 1% increased by nearly 2 °C in nitrogen atmosphere and by 5.27 °C in air atmosphere. These results prove that the CNF is a key role in the thermal stability of DPNR-g-PMMA.

Article Code:23067

# cellulose nanofibers, deproteinized natural rubber, methyl methacrylate, thermal degradation, thermal oxidative degradation

Page: 19-26

Field: Chemical Engineering
4. Study on Influencing Factors on Properties of Injectional Compounds Based on Polyethylene and Silica from Waste Materials

Nguyen Pham Duy Linh, Nguyen Huy Tung*, Bui Chuong

In this study, silica from waste materials – rice husk (silica TT) and by-product of quartz stone grinding (silica TA) – modified with bis (3-ethoxy propylsilane) tetrasulphide (TESPT) were characterized. Their particle sizes are mostly under 30μm, quite suitable for plastic filling. Some factors influencing the properties of injectional compounds based on HDPE/LDPE blend and silica from waste materials were carried out. It is revealed processing conditions including a maximum temperature of 190-200oC and screw speed of 50-100 rpm are suitable for stable compound properties. Processing aid additives ratios such as stearic acid/zinc stearate and PE wax/paraffinic oil affect mostly compound melt flow index, but HDPE/LDPE ratio strongly affects both melt flow index and mechanical properties of compounds: change HDPE/LDPE ratio from 90/10 to 60/40 decrease tensile from 15.2MPa to 12.5MPa, bending strength from 15.5MPa to10.6MPa while melt flow index decrease almost twice but elongation at break increase from 34.4% to 72.2%. Also, using PE-g-MA as a compatibilizer may remarkably enhance the mechanical properties of compounds: the PE-g-MA content of 0.8-1.0 (%wt) increases tensile, bending strength, and impact resistance of compound by about 10-30% in comparison with the compound without PE-g-MA.

Article Code:23070

# Injectional compounds, polyethylene, waste silica, compounds, processing conditions

Page: 27-34

Field: Chemical Engineering
5. Initial research on the oxidation capacity of 1%CuO – 6CeO2 – 4ZrO2 catalyst by TPR-H2 for CO clean up reaction in H2-rich stream (CO-PROX)

Ta Dinh Quang, Vuong Thanh Huyen, Le Minh Thang*

The 1%CuO – 6CeO2 – 4ZrO2 catalyst were synthesized by sol-gel method with two different procedures: (i) bringing CuO on CeO2-ZrO2 support, (ii) sol-gel at the same time CuO-CeO2-ZrO2. Their catalyst will be examined in the preferential oxidation of carbon monoxide to remove a small quantity of CO in an H2-rich stream (the new direction research in Viet Nam), fueling the proton exchange membrane fuel cell (PEMFC) energy system. The findings of the TPR-H2 experiment indicate that the catalyst produced through the (i) method exhibits an α reduction peak at 174°C, which shows the effective dispersion of copper species. In combination with EPR results, the author anticipates a significant dispersion arising from isolated copper, recognized as a pivotal site in the CO-PROX reaction per numerous reputable studies. The method (ii) synthesized the catalyst does not provide a clear indication of the oxidation behavior of Cu-species. Therefore, it can be inferred that this catalyst is inappropriate for the low-temperature CO-PROX reaction.

Article Code:23077

# CuO-CeO2-ZrO2, TPR-H2, CO-PROX reaction, PEMFC

Page: 35-42

Field: Chemical Engineering
6. Creation of the Bamboo Route, a Contribution to Net Zero by 2050 in Viet Nam

Diep thi My Hanh*, Jacques Gurgand, Pham Bach Viet, Nguyen Khac Dieu, Marc Pignal, Regine Vignes Lebbe

The Phu An bamboo village, created in 1999, maintains over 200 taxa of living bamboo, collected in Viet Nam, Laos and Cambodia, and was awarded the UNDP Equatorial Prize in 2010 [1] [17]. This ex-situ conservation not only provides data for basic research and preserves biodiversity resources, but also contributes to actions on CO2 to reduce the greenhouse effect in climate change and create sustainable livelihoods for the community..
From the Phu An Bamboo village, the "Bamboo Route" has been built since 2016 from the north to the south of Viet Nam, with the aim of multiplying bamboo in situ conservation sites, associated with research programs and public awareness actions on the importance and environmental benefits of bamboos.
Along the bamboo route, an ex situ conservation site has been developed at Dong Thap with plants of 67 different vernacular species, another at Phan Rang, in the arid region, with 62 species, and a third at Dak Nong, where the climate is more favourable, with 12 different vernacular species from the in situ conservation site at Chieng Ban Son La where 19 vernacular species have been recorded.
Thanks to its fast-growing characteristics and large biomass production, bamboo plays an important role in carbon sequestration. Research to mesure CO2 absorption was done in three different habitats on three different bamboo species. The CO2 absorption capacity of Bambusa blumeana Schultes in Gao Giong - Dong Thap province indicates an important role of this thorny bamboo under climate change conditions. On the "Bamboo Route" , we studied also the surface area of bare soil from north to south, except in the Mekong delta. This enables us to estimate how planting 50% of these areas could contribute to Viet Nam’s Net 0 2050 target.

Article Code:23053

# carbone absorption, conservation, environmental benefits, Bamboo Route.

Page: 43-51

Field: Environmental Science and Technology
7. Assessment Environmental and Social Impacts for the Rice Straw Utilization Technical Models to Promote Circular Economy for Rice Production in Chau Thanh District - An Giang Province

Nguyễn Thị Kim Chi, Nguyễn Văn Nhân, Nguyễn Thị Vân Hà*

The study objective is to provide an initial scientific basis for calculating CO2 equivalent (CO2e) emission reduction from the three technical models such as rice-straw composting, rice-straw fermented for cattle feed, and straw mushroom production, which are rice-straw utilization alternatives instead of open-burning them in Chau Thanh district. The study calculation is based on the surveyed practical database, the theoretical emission factors (EF), and the implementation of EasyPol-Ex software version 5 (Ex-Act) to estimate the amount of CO2e emissions when switching. The results show that in 2022, Chau Thanh could avoid 330,236 tons of CO2 emissions by burning 171,637 tons of rice straw. The estimated amount of CO2 emitted from harvesting and rolling rice straw by machine was 4.375 g CO2e per kilogram of rice straw. The EF for transportation of rice straw to model implementation places was 740 gCO2e/kg. The additional EFs for mushroom, composting, and animal feed production models were 222g, 172g and 60g CO2e/kg, respectively. Results indicate that although the EF of rice straw collection and transportation was still high, the total CO2e from three models (including transportation) was still lower than the EF from straw burning. In addition, farmers who own the paddy field earned an extra 500,000 VND/ha per crop, and farmers earned an extra about 1.7 to 2.3 million VND per crop, depending on the model applied. The successful implementation of technical models promoted the concept of circular economy applied to rice production industries.

Article Code:23049

# CO2e emissions; open-burning; rice-straw composting, rice-straw fermented, An Giang, circular economy.

Page: 52-58

Field: Environmental Science and Technology
8. A model-based mechatronic system design and integration process

Giang-Nam Le*, Tra-Giang Nguyen Thi

In contemporary mechatronic product development, embracing an interdisciplinary approach has become imperative to manage potential integration risks. This research paper introduces a viable solution that combines Automation Studio and the VDI 2206 methodology to design mechatronic systems. The study's findings highlight the efficacy of this interdisciplinary approach in effectively addressing early challenges associated with multi-domain integration. It enables simultaneous evaluation and resolution of limitations inherent in traditional design methods. Successfully applied to develop an automated garment folding machine with a PLC controller, the proposed process proves to be a valuable tool in optimizing mechatronic system development. The system, designed using this process, relies on a real-time computational model as its foundation, laying the groundwork for constructing a digital twin in the future. This ensures a comprehensive representation of the system, facilitating enhanced understanding and performance assessment during the development and operational phases. The adoption of such an approach signifies a significant step forward in advancing mechatronic engineering and ensuring the successful realization of complex and efficient systems.

Article Code:23052

# VDI 2206, interdisciplinary engineering, Mechatronics, PLC, Automation Studio

Page: 59-69

Field: Mechanical Engineering