Revalorization of sunflower stalk pith as feedstock for the coproduction of pectin and glucose using a two-step dilute acid pretreatment process

Background Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step dilute sulfuric acid treatment process was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose. Results In this study, pectin was firstly extracted under mild acid condition to avoid pectin degradation, which was conducted at 90 °C with a pH of 2.0 for 2 h, and ~0.14 g/g of pectin could be recovered. Then the remaining solids after pectin extraction were subjected to the reinforced treatment process with 0.75% H2SO4 at 150 °C for 30 min to further improve enzymatic hydrolysis efficiency. Moreover, by combining a fed-batch enzymatic hydrolysis strategy, a solid loading content of 16% was successfully achieved and the glucose titer reached 103.1 g/L with a yield of 83.6%. Conclusion Finally, ~140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work puts forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.

Comparison of Cellulose Dissolution Behavior by Alkaline and Sulfuric Acid Solvents and Their Films’ Physical Properties

Three alkaline mixtures (NaOH/thiourea, NaOH/urea/thiourea, NaOH/urea/ZnO) and sulfuric acid were used at low temperatures as cellulose solvents, and their cellulose solubility and films’ physical properties for bleached chemical wood pulps and cotton linter were compared. Their degree of polymerization (DP) was controlled to 600–800 before dissolution. Among the alkaline solvents, NaOH/urea/ZnO gave the film the highest tensile strength and stretch. When compared to sulfuric acid, NaOH/urea/ZnO gave lower strength properties but higher crystallinity indices in the films. While alkaline solvents could not dissolve the high DP cellulose (DP ~ 2000), sulfuric acid could dissolve the high DP cellulose at below zero Celsius temperature, and the strength properties of the films were not much different from that of the low DP one. It appeared that the low-temperature sulfuric acid treatment did away with the cellulose’s DP controlling stage; it decreased cellulose DP very quickly for the high-DP cellulose at the initial stage, and as soon as the cellulose DP reached a DP low enough for dissolution, it began to dissolve the cellulose to result in stable cellulose solution.

Studying digestion conditions of Vietnamese monazite with acid sulfuric for the recovery of rare earth elements, thorium and uranium

The monazite ore is a commercial source of Th, U and rare earth in Vietnam. There are two methods, which were often applied to decompose monazite ore are alkaline and sulfuric methods. But in Vietnam, sulfuric method is more suitable due to the simple technology. In sulfuric acid treatment its breakdown using sulfate process for recovering of REEs, thorium and uranium. In this study, the parameters such as ore/acid ratios, the digestion temperature and the time of degestion were investigated to determine optimal digestion conditions for high recovery of main ingredients (REEs, Th, U) in monazite ore. The results shown that the optimal parameters for the digestion are ore/acid ratio 1.2:1, digestion temperature - 300oC and time of digestion - 1 hour, the recoveries for REEs, Th and U are namely 90%, 85% and 65%, respectively.

Surface Bioactivation of Polyether Ether Ketone (PEEK) by Sulfuric Acid and Piranha Solution: Influence of the Modification Route in Capacity for Inducing Cell Growth

The aim of this study was to promote bioactivity of the PEEK surface using sulfuric acid and piranha solution. PEEK was functionalized by a sulfuric acid treatment for 90 s and by piranha solution for 60 and 90 s. Chemical modification of the PEEK surface was evaluated by infrared spectroscopy, contact angle analysis, cytotoxicity, cell adhesion and proliferation. The spectroscopy characteristic band associated with sulfonation was observed in all treated samples. PEEK with piranha solution 60 s showed an increase in the intensity of the bands, which was even more significant for the longer treatment (90 s). The introduction of the sulfonic acid functional group reduced the contact angle. In cytotoxicity assays, for all treatments, the number of viable cells was higher when compared to those of untreated PEEK. PEEK treated with sulfuric acid and piranha solution for 60 s were the treatments that showed the highest percentage of cell viability with no statistically significant differences between them. The modified surfaces had a greater capacity for inducing cell growth, indicative of effective cell adhesion and proliferation. The proposed chemical modifications are promising for the functionalization of PEEK-based implants, as they were effective in promoting bioactivation of the PEEK surface and in stimulating cell growth and proliferation.

Effective Adsorption of Nutrients from Simulated Domestic Sewage by Modified Maifanite

Modified maifanite (MMF) was prepared by synthesized method with sulfuric acid treatment and high temperature calcination, and evaluated as an effective adsorption material to remove the nutrient salt in waste watery. Compared with the raw maifanite (RMF), the MMF exhibited the higher adsorption capacity and higher removal efficiency. The results showed that the adsorption rates of total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH3-N), nitrate nitrogen (NOx-N) and Chemical Oxygen Demand (COD) by MMF (RMF) were86.7% (76.7%), 44.9% (34.5%), 29.1% (20.8%) and 79.8% (13.0%) respectively at 20 ℃ for 24 h. MMF kept the basic structure and composition of maifanite with stronger surface roughness and more adsorption active sites. This study suggests that MMF can be further applied to treat domestic sewage and eutrophic water.

MICROWAVE IRRADIATION OPTIMIZATION FOR EFFICIENT LIGNIN REMOVAL FROM COCOA SHELL WASTE USING ALKALI

This paper reports a study to determine the optimum conditions of microwave in assisting alkali treatment for removing lignin from cocoa shell waste (CSW). The CSW was mixed with 5% of NaOH solution at the ratio of 1: 10 of weight to volume of the alkaline before being irradiated in a microwave oven. Various microwave powers (200-400 W), temperature settings (60-80 °C) and irradiation times (10-20 min) were tested on 15 samples set by the Box-Behnken design. The lignin removal was analysed using a 72 % sulfuric acid treatment method. A quadratic equation was employed to the response surface and statistical analysis conducted to confirm the adequacy of the model. The plots show that the optimum microwave conditions are 400 W, 76 °C and 19 min, which were capable to remove 86.57% of lignin. Thermogravimetric analysis and micrographs revealed different decomposition temperature of lignin and morphology of extensively-pored surface of treated CSW, respectively. ABSTRAK: Kajian ini adalah berkaitan penentuan keadaan optimal ketuhar gelombang mikro bagi membantu menyingkirkan lignin daripada sisa kulit biji koko (CSW) menggunakan rawatan alkali. CSW dicampurkan dengan larutan NaOH 5 % pada nisbah 1:10 berat kepada isipadu larutan alkali sebelum campuran dipanaskan ke dalam ketuhar gelombang mikro. Pelbagai keadaan ujian dibuat pada ketuhar gelombang mikro seperti tenaga (200-400 W), suhu ketuhar (60-80 °C) dan masa pemanasan (10-20 min) ke atas 15 sampel mengikut reka bentuk statistik Box-Behnken. Kadar penyingkiran lignin ditentukan dengan menggunakan kaedah rawatan larutan asid sulfurik berkepekatan 72 %. Persamaan kuadratik telah digunakan ke atas permukaan respon dan analisis statistik telah dilakukan bagi memastikan kesesuaian model. Plot-plot menunjukkan keadaan optima ketuhar gelombang mikro adalah pada 400 W, 76 °C dan 19 min iaitu berupaya menyingkirkan sebanyak 86.57% lignin. Analisis thermogravimetri dan mikrograf masing-masing menunjukkan perbezaan suhu penguraian lignin dan morfologi permukaan CSW yang dirawat didapati berliang dengan banyaknya.

Revalorization of Sunflower Stalk Pitch As Feedstock for the Coproduction of Pectin and Glucose Using a Two-Step Dilute Acid Pretreatment Process

Background: Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step sequential dilute sulfuric acid treatment combined with subsequent enzymatic hydrolysis was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose. Results: In this study, pectin was firstly extracted with a mild condition to avoid pectin degradation, which conducted at 95℃ with a pH of 2.0 for 2 h, and approximately 0.12 g/g of pectin could be recovered. Then the remaining solids followed by extracted pectin were subjected to the reinforced treatment process with 0.75% H2SO4 at 150 oC for 30 min to further improving enzymatic hydrolysis efficiency. Moreover, a fed-batch enzymatic hydrolysis was successfully performed with a solid 16% content, the glucose titer reached 103.1 g/L with a yield of 83.6 %.Conclusion: Finally, approximately 140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work put forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.

Spartium junceum (Spanish broom).

Genetics: The chromosome number reported for S. junceum varies from 2n = 48, 2n = 52, 2n = 54 to 2n = 56 (Afzal-Rafii et al., 1986). Reproductive Biology: S. junceum is a fast-growing, perennial shrub that can live for up to 30 years. Its flowers are hermaphroditic, zygomorphic, yellow in colour and borne in terminal clusters or racemes. It is predominantly a xenogamous (outcrossed) species and its flowers are pollinated by insects, particularly bees (López et al., 1999; Zouhar, 2005). S. junceum begins to produce seeds when plants are two to three years old. This species is a prolific seeder with the potential to produce between 7000 and 10,000 seeds per plant in just one season (Zouhar, 2005; Silva et al., 2008). Under natural conditions, germination rates are approximately 70%. Scarification treatments, such as hot water immersion, dry heat, sulfuric acid treatment and water soak, effectively break seed dormancy and increase germination rates to between 78% and 92% (Travlos et al., 2007). This species produces large seed banks and seeds can remain viable in the soil for up to 30 years (DiTomaso and Kyser, 2013; Geerts et al., 2013; USDA-NRCS, 2017). Physiology and Phenology: S. junceum has a range of xerophytic adaptations. The stem is adapted to reduce the effects of overheating through the profiled positioning of the vegetative parts of the plant. The species has small leaves, which it loses before summer to reduce transpiration and to increase its tolerance to drought stress. The grass-shaped stem helps to reduce the total exposed area of the plant, whereas the root is well developed and ramified. The leaves of S. junceum have thick cuticles with a waxy layer and the plant produces oils that reduce evapotranspiration, which also reduces the temperature of the plant's microenvironment (Bezić et al., 2003).In California, shoots of S. junceum begin to grow in late winter and early spring. They elongate quickly and produce leaves with long internodes by March, with the most rapid growth occurring in May. Leaf longevity is four months or less, although stem photosynthesis occurs all year. Flowers are produced in May and pods mature in late June and early July (Nilsen et al., 1993; Zouhar, 2005). In South Africa, it has been recorded flowering from August to November, while in Lebanon it flowers from May to August (Invasive Species South Africa, 2017). In Europe, S. junceum has been recorded in flower from June to September, and in fruit from August to October (PFAF, 2017). AssociationsS. junceum has a symbiotic relationship with soil bacteria that form nodules on its roots and fix atmospheric nitrogen (PFAF, 2017). Environmental RequirementsS. junceum can grow on poor, dry and stony limestone soils. It is well adapted to rocky or sandy soils, clays, loams and sandy loams with a pH in the range of 5.5 to 7.5; it is also adapted to soils with high salt concentrations. This species has morphological adaptations to xerophytic conditions that allow it to endure severe drought. It thrives in full sun and can tolerate urban pollution, salt-laden winds near the coast and temperatures as low as -10°C (Bezić et al., 2003; Zouhar, 2005; Silva et al., 2008; DiTomaso and Kyser, 2013; Geerts et al., 2013).