Aims: The aim of the study was to use Response Surface Methodology (RSM) to find optimal experimental design for wastewater treatments from office paper recycling. In this way, interactive effects of treatment factors were evaluated, including microwave power (MW) and durations with centrifuge time while turbidity of wastewater was chosen as the dependent output variable or an optimal response. Methodology: The RSM approach was utilized for optimization of the process parameters and identifying the optimal conditions for the removal of turbidity in paper recycling wastewater. In this regard, a three-factor RSM were selected, using MW irradiation power (Watts), durations (seconds) and centrifuge time (min). Statistical analysis of variance (ANOVA) was carried out to identify the adequacy of the developed model. In this case, specially prepared office papers (one-side laser printed) were subjected to standard paper recycling procedure for obtaining wastewater at laboratory conditions. The experimentally derived RSM model was validated using range of statistical parameters. Conclusions: The study revealed that under the RSM optimized conditions, a marked reduction in the turbidity of wastewater was observed for both groups studied. The R2, R2(adj) and R2(pred) values were indicates, the developed model was significant which revealed a well agreement between the experimental data and proposed model. In this approach, the R2=99.710% and lack-of-fit value were found to be 0.111 (p>0.05), which shows the model and the data consisted to each other. The lowest turbidity value was found with 150.000 Watts and 60.000 seconds in MW conditions with 15.000 minutes of centrifugation time, experimentally. With employing these variables, the turbidity value of 6.65 NTU was determined. However, the highest turbidity value of 18.013 NTU was found with MW power of 200.00 Watts with 40.000 seconds of durations and 1.591 minute of centrifugation time. It is important to note that with using optimized parameters, the turbidity value of 1.43 NTU was calculated while 1.47 NTU was found with experimentally.
Wood as a natural biological polymer, has significant advantages compared to other building materials. However, it has to be impregnated or surface coated since it does not have a resistant structure in outdoor conditions. In this study, Scots pine samples were treated with nano cerium oxide (CeO2) at 0.1%, 0.2, 0.5, 0.7, 1, 2, 3, 4 and 5 concentrations, and then were exposed to accelerated weathering. Color changes and surface chemistry were determined after 2, 4, 6, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144 and 168 hours of weathering period. Tanalith-E was used as a reference chemical at the same concentration levels. Efficiency of cerium oxide treated samples was compared with the samples treated with Tanalith-E. Thus, potential of cerium oxide instead of reference chemical in improving the surface properties of wood exposed to outdoor conditions was evaluated. As a result of the study, the surface properties of the samples treated with cerium oxide and Tanalith-E were better protected in comparison to the control samples. Initial weathering periods had greater impact on the properties. It was found that cerium oxide showed similar results to the copper-based wood preservative.
The effects of two mineral adducts (dolomite and olivine) as proportion in Calabrian pine wood chip based-experimental panels which bonded with synthetic adhesive (UF) were evaluated. It appears both minerals (P: calabrian pine wood chip-, X: Dolomite- Y: Olivine in composite proportions) improve the water repellent efficiency (WRE) properties at certain extent. In all experimental procedure, WRE increased with dolomite and olivine proportions higher than >10% in board formulations. The highest WRE of -34.2% and -35.4% were found with PX5 and PY5 samples that made with 1:1 (w/w) dolomite/wood and olivine/wood formulations, respectively. Like water sorption, similar trend was also found for thickness swelling (TS) properties. The lower TS values were found to be in range of -11.2 to -56.4% for dolomite-, and -55.5 to -69.5% for olivine based panels, respectively. Only samples of PX1, which produced 1:9 dolomite/wood chips (w,w, %) proportions, show higher IB value than control (PX0: 0.87 MPa vs PX1: 0.99 MPa) while rest of dolomite- pine wood panels show lower IB values. In contrast to dolomite, olivine appear to be improving effects on IB properties at certain conditions. The highest IB value of 1.21 MPa was found with sample PY4, which produced 4:6 olivine/wood chips (w,w, %) proportions, indicate approximately 39.1% higher IB value than control. It is notable that olivine seems to more effective than dolomite at similar board properation formulations in terms of lowering TS, WA and creating higher internal bond strength properties than dolomite based panels at similar experimental conditions. However, only sample of PY1, made with 1:9 (w, w,%) olivine/wood and proportions, show higher bending strength (13.27 MPa) and elasticity (2468.2 MPa than control (PY0:12.75 MPa vs 2245.2 MPa).
Doğal bir mühendislik yapı malzemesi olan ahşap, dış ortam koşullarında dış cephe, yürüyüş yolları, kamelya, ev yapımı gibi pek çok kullanım yerlerinde değerlendirilebilirken, iç mekan kullanımı için de sıklıkla tercih edilen dekoratif bir malzeme olmaktadır. Ahşabın iç mekan malzemesi olarak kullanımında, özellikle mobilyada yüzey görünümü ve renk stabilizasyonu çok önemlidir. Ahşap ürünlerde dış ortam koşullarına benzer şekilde iç ortamda da ligninin foto-oksidasyonu sonucu zamanla sararmalar ve koyulaşmalar görülmektedir. Ahşabın güneş ışınlarına karşı dayanımının belirlenmesi amacıyla laboratuvar koşullarında UV, nem ve sıcaklığın değişken döngülerinde belirli bir sürede yapay yaşlandırma testine tabi tutulması yaygın bir uygulama olarak karşımıza çıkmaktadır. Ahşabın servis ömrünün doğru tespit edilmesi için laboratuvar koşullarındaki testlerin yanı sıra doğal ortam koşullarına maruz bırakılma gerekli görülmektedir. İç ortam koşullarında pencere yakınındaki kullanım yeri olan ahşap malzemeler camdan geçen güneş ışıkları nedeniyle renk değişimi ve yüzey bozunmasına maruz kalabilmekte ve bu bozunma UVA-351 nm’lik lambaların kullanılması ile yapay olarak simüle edilebilmektedir. Bu derleme çalışmasında, ahşap malzemenin iç ortam koşullarında kullanımı sırasında maruz kalabileceği bozundurucu faktörlerin ahşabın özelliklerine etkisi araştırılmıştır. Çalışmada farklı yapay ve doğal iç ortam yaşlandırma test yöntemleri irdelenmiş ayrıca yapay ve doğal yaşlandırma arasında modelleme çalışmalarına da değinilmiştir.
In this study, we conducted a novel method by using a household type Microwave Owen (MW) under selected operational parameters (power and time) to treat wastewater from paper recycling under laboratory conditions. We seek to evaluate changes of the MW experimental parameters, comparatively. All measured pH values were found to be in very narrow range, between pH 7.10 (BII) and pH 7.53 (DIV), in slightly alkaline range (>7.0). However, the highest Electrical Conductivity (EC) difference was found to be 46 µS/cm. The 60 seconds MW irradiated samples at four power levels (90-, 180-, 270-, 360 Watts) showed higher ORP values than control (C1: 195 mV) while the highest ORP value of 213 mV was found with sample treated 360 W and 60 seconds (DIV). It is notable that sample DIV showed the highest pH, EC, ORP and TDS value. The control sample had turbidity value of 42.5 NTU. In all MW power levels and durations, turbidity removal was apparent which MW impact on turbidity. The lowest turbidity value of 22.2 NTU was found with sample DIV which was the highest rate of turbidity removal efficiency (DIV: 86.2%). The present study revealed that MW irradiation could be used to effectively reduce the selected physicochemical parameters that may assist in the description of wastewater quality.
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