Waterless sterilization and cleaning of sheep wool fiber using supercritical carbon dioxide

There is increasing concern regarding the existing sheep wool processing technology in the textile industry owing to the enormous volume of toxic effluents generated. The application of supercritical carbon dioxide (scCO2) in sheep wool processing is cleaner and increases wool fiber production while avoiding toxic effluent generation. scCO2 is a novel clean technology that can be utilized in sheep processing for sterilization, cleaning, and drying sheep wool at the same time. In the present study, scCO2 was used to treat sheep wool with varying pressure, temperature, and treatment time. These parameters influence the scCO2 treatment of sheep wool fiber through the inactivation of microorganisms and improvement of the whiteness index. The identification of bacteria in sheep wool was carried out based on biochemical analysis by molecular means, using 16s rRNA sequencing. It was found that scCO2 completely inactivated the microorganisms present in sheep wool and potentially enhanced the percentage whiteness index at the highest pressure of 30 MPa, temperature of 80°C, and treatment time of 80 min. Several analytical methods were employed to assess the physicochemical, thermal, and morphological properties of untreated and scCO2 treated sheep wool fibers. The results show that scCO2 effectively removes the impurities and completely inactivates the microorganisms present in sheep wool. The findings of the present study reveal that scCO2 can be utilized as an alternative treatment technology for sheep wool processing in the textile industry.

Potential utilization of quartz sand and kaolin from tin mine tailings for whitewares

Purpose. To do experimental research into the potential utilization of residual quartz-based sands and kaolin from the tin mine tailings in Bangka Belitung Province, Indonesia. Methods. Process of raw materials beneficiation by washing, vibration on the screen, magnetic separation. Manufacturing whiteware from beneficiated quartz sand, beneficiated kaolin, ball clay and feldspar. The whiteware properties were analyzed in terms of shrinkage, water absorption, flexural strength, and whiteness index. Findings. The amount of iron oxide in the quartz sand and the kaolin was reduced by beneficiation process from 1.12% and 1.06 to 0.51% and 0.5%, respectively. The whiteware specimens showed the required physical and mechanical properties. Thus, these raw materials can principally be utilized for the manufacture of whiteware ceramic items with whiteness index up to 68.3. Originality. Quartz sand and kaolin extracted from tin mine tailings were used after beneficiation of raw materials for whiteware manufacture. Practical implications. This research can provide practical solution to the problem related to mine tailings rich in quartz and kaolin which can be utilized for manufacturing whiteware. Keywords: tin mine tailings, quartz sand, kaolin, magnetic separation, whiteware ceramics

Color Stability and Staining Susceptibility of Direct Resin-Based Composites after Light-Activated In-Office Bleaching

This study evaluated color stability and staining susceptibility of five direct resin-based composites (RBCs) subjected to light-activated in-office bleaching with 40% hydrogen peroxide (HP). The test materials included 5 RBCs, which consisted of one nano-filled, one sub-micron, one bulk-filled, and two nano-hybrid RBC types. Ten disc-shaped specimens of each RBC were fabricated and divided into bleaching (BLE) and non-bleaching (CON) groups (n = 5 for each group). Specimens were then immersed in red wine solution over 4 h. A spectrophotometer was used to obtain Commission Internationale de l’Eclairage (CIE) L*a*b* parameters for each of the following periods tested: before bleaching (TBA), after bleaching (TBL), and after staining (TST). Color stability and staining susceptibility were evaluated using two metrics, CIEDE2000 color differences (ΔE00) and whiteness variations using the whiteness index (ΔWID). Data were analyzed using repeated measures two-way analysis of variance (ANOVA) (α = 0.05). Statistically significant and clinically unaccepted ΔE00 and ΔWID were observed for all tested specimens between TBA and TBL. The nano-hybrid type RBCs showed the highest discoloration among materials after bleaching treatment. The BLE group exhibited significantly higher ΔE00 and ΔWID than the CON group for all the tested RBCs between TBA and TST. The sub-micron type RBC showed the highest discoloration among materials after immersion in the red wine. Conclusion. The light-activated in-office bleaching with 40% HP’s influences on color and whiteness index were material-dependent. The use of bleaching treatment also increased the susceptibility to red wine for all RBCs.

Karakteristik Fisikokimia Pati Ubi Banggai (Dioscorea alata)

Ubi Banggai merupakan ubi khas dari Kepulauan Banggai, dengan jumlah varietas yang banyak. Ubi Banggai merupakan sumber karbohidrat yang salah satu komponen penyusunnya adalah pati. Karakteristik fisikokimia pati dari ubi Banggai belum diketahui, sehingga penelitian ini bertujuan untuk mengevaluasi karakteristik pati dari tiga varietas ubi Banggai (Baku Pusus, Baku Tuu Oloyo, dan Baku Boan). Pati ubi Banggai diekstraksi dan dianalisis sifat fisikokimianya yang meliputi kadar pati, amilosa, amilopektin, morfologi granula, warna, profil pasting, kemampuan mengembang, kelarutan, kekuatan gel, dan sineresis. Rendemen setiap varietas relatif rendah, yaitu Baku Pusus (8,66%), Baku Tuu oloyo (5,09%) dan Baku Boan (4,56%). Ketiga varietas mengandung kadar pati 88,00-88,89%, yang disusun oleh 60,29-62,88% amilosa dan amilopektin 25,12-28,65%. Granula pati ubi Banggai berbentuk ellipsoid, polihedral, dan triangular dengan ukuran panjang 17,94-23,59 µm dan lebar 13,97-16,72 µm. Hasil analisis warna pati kering ubi Banggai menunjukkan ubi Baku Pusus dan Baku Tu Oloyo memiliki nilai whiteness index (WI) yang tinggi dan browning index (BI) yang rendah, sedangkan pati ubi Baku Boan memiliki nilai WI yang paling rendah dan nilai BI paling tinggi. Hasil analisis RVA menunjukkan pati ubi Banggai memiliki suhu pasting yang tinggi (80,10-80,35 °C). Pada fase pemanasan, pasta ubi Banggai memiliki viskositas puncak yang tinggi dan mengalami viskositas breakdown. Pada fase pendinginan, pasta ubi Banggai memiliki viskositas setback dan viskositas akhir yang tinggi. Pati Baku Pusus memiliki kelarutan yang tinggi, kemampuan mengembang yang terbatas, kekuatan gel yang tinggi, namun mengalami sineresis.

Least Square Support Vector Regression-Based Model for Whiteness Index of Cotton Fabric Prediction

The textile bleaching process uses a hydrogen peroxide (H2O2) solution in alkali pH associated with high temperature is the commonly used bleaching procedure in cotton fabric manufacture. The purpose of the bleaching process is to remove the natural colour from cotton to obtain a permanent white colour before dyeing or shape matching. Normally, the visual ratings of whiteness on the cotton are measured by the whiteness index (WI). Notice that lesser research study is focusing on chemical predictive modelling of the WI of cotton fabric than its experimental study. Predictive analytics using predictive modelling can forecast the outcomes that can lead to better-informed cotton quality assurance and control decisions. Up to date, limited study applying least square support vector regression (LSSVR) based model in the textile domain. Hence, the present study was aimed to develop the LSSVR-based model, namely multi-output LSSVR (MLSSVR) using bleaching process variables to predict the WI of cotton. The predictive accuracy of the MLSSVR model is measured by root mean square error (RMSE), mean absolute error (MAE), and the coefficient of determination (R2), and its results are compared with other regression models including partial least square regression, predictive fuzzy model, locally weighted partial least square regression and locally weighted kernel partial least square regression. The results indicate that the MLSSVR model performed better than other models in predicting the WI as it has 60–1209% lower values of RMSE and MAE as well as it provided the highest R2 values which are up to 0.9985.

Photo-bleached agar extracts from Gracilariopsis heteroclada

Agar is a strongly gelling polysaccharide extracted from gracilarioids, which is processed through conventional alkaline pre-treatment and chemical bleaching. However, the use of chemical bleaching agents has associated health risks to humans and the environment. The aim of the present study was to determine the effects of photo-bleaching in combination with NaOH pre-treatments at 5, 10 and 15% concentrations on the physico-chemical properties of agar extracted from Gracilariopsis heteroclada. The results highlighted that the gel strength of photo-bleached agar extracts PBA-15 (1822.00 g cm−2), PBA-10 (1465.60 g cm−2), and PBA-5 (1067.70 g cm−2) were significantly higher than in either a commercially sourced agar reference sample (756.20 g cm−2) or a chemically bleached agar (390.94 g cm−2). The physico-chemical properties of PBA extracts fell within the acceptable limits of food-grade agar. Photo-bleached agar extracts (PBA-5, PBA-10, PBA-15) also exhibited a higher lightness (L*) and whiteness index (WI) which makes these agars ideal for microbiological use. This study demonstrated that photo-bleaching by solar irradiation improved the physico-chemical properties of agar from G. heteroclada without the use of a chemical bleaching agent.

Structural FTIR analysis of cellulose functional groups isolated from Leucaena leucocephala pods using different bleaching agents.

In this study, extracted cellulose fibres were successfully isolated from Leucaena leucocephala pods through an efficient alkaline treatment and bleaching method using different bleaching agents such as 5 wt.% of sodium chlorite (NaClO2), 5 wt.% of oxalic acid (C2H2O4), 5 wt.% of potassium permanganate (KMnO4) and 5 wt.% of sodium hypochlorite (NaClO), respectively. The functional group of the cellulose fibres were analysed by using attenuated total reflection infrared (ATR-IR) spectroscopy. The ATR-IR spectra reported that the Leucaena leucocephala fibres after being given chemical treatment with 5%w/w of NaClO lead the similar functional group with the commercial cellulose due to removal hemicellulose and lignin. The content cellulose of final product was 89.4% was measured by the chemical composition test. Meanwhile, the whiteness index of Leucaena leucocephala fibres treated with 5 wt.% NaClO was 78.5%, which was the highest. The results of ATR-IR, chemical composition test and whiteness index were indicated that the sample of Leucaena leucocephala pods presents the structure of cellulose.