On the behaviour, mechanistic modelling and interaction of biochar and crop fertilizers in aqueous solutions

Although the benefits of applying biochar for the purposes of soil conditioning and crop productivity enhancement have been demonstrated, relatively few studies have elaborated on its causal mechanisms, especially on the biochar-fertilizer interaction. Thus, in the present study, the ex-situ adsorptive potential of base activated biochar (BAB) towards plant nutrient immobilization and removal from aqueous solutions was investigated. Napier grass (Pennisetum purpureum) was utilized as the precursor to prepare slow vacuum pyrolysed char and its affinity towards adsorption of urea was examined at various process conditions. Low sorption temperatures, moderate agitation speeds and high initial concentration were seen to favour greater urea uptake by BAB. The sorption was exothermic, physical, spontaneous and had a pseudo-second order kinetic fit. Both surface and intra-particle diffusion governed the removal and immobilization of urea. Furthermore, process mass transfer was limited by film diffusion of urea to the external surface of the BAB. Equilibrium studies suggested that Dubinin-Radushkevich is the most appropriate model to describe the urea-BAB behaviour with maximum uptake, estimated to be 1115 mg·g−1. Through such ex-situ analysis, it could be possible to have prior knowledge, quantification and differentiation of the potential of chars manufactured from various feedstocks. This could then be used as an effective screening step in designing appropriate biochar-fertilizer systems for soil conditioning and help reduce the time and effort spent otherwise in long-term field studies

Ultrasound assisted citronella oil in water nanoemulsion and comparison with conventional methods

This study involved the acoustic cavitation aided process intensification of citronella oil-based nanoemulsion with varying process parameters. A citronella oil (10 wt. %) in water emulsion was prepared at optimized parameters such as sonication time of 20 min, surfactant concentration of 7.5 wt. % of the total emulsion with (Hydrophilic-lipophilic balance) HLB value of 12 and power amplitude of 35% (of the total power of 750 W). The prepared emulsions stability was assessed over visual observation and kinetic stability of the emulsion after formulation with 7, 30 and 90 days’ time interval term as long-term stability reported as a fraction of phase separation in percentage (f (%)). The ultrasonically prepared emulsion was found to more stable with the mean droplet diameter (MDD) of 22-23 nm, whereas, conventionally prepared emulsion get separated and creamed within the day as well as formulation required more process time and energy dissipation

Sustainable Functional Coloration of Linen Fabric Using Kigelia Africana Flower Colorant

Natural dyes are gaining momentum in the textile industry due to their non-toxic and eco-friendly nature. The enhanced demand of natural-dyed functional textile materials resulted in increased interest among the research community to explore new sources of natural dyes which could be utilized for functional coloration of textile materials. Kigelia Africana flower is known for various medicinal properties and thus can be utilized for functional coloration of textile materials. In the current study, the pre-mordanting process has been exploited to evaluate the dyeing condition of the linen fabrics by using different mordants such as; alum, ferrous sulfate, and copper sulfate. The effect of mordants on the color strength of the dyed fabrics was analyzed and correlated with wash fastness tests results. The dyed fabrics analysis has been carried out in terms of their color strength and color coordinates (L*a*b*). The functional properties like radical scavenging activity, antibacterial activity, and UV protection properties were thoroughly investigated to determine the functionality of dyed fabrics. The dyed samples displayed satisfactory fastness and color strength along with efficient antibacterial, antioxidants and UV protection properties

Cavitation milling of natural cellulose to nanofibrils

Cavitation holds the promise of a new and exciting approach to fabricate both top down and bottom up nanostructures. Cavitation bubbles are created when a liquid boils under less than atmospheric pressure. The collapse process occurs supersonically and generates a host of physical and chemical effects. We have made an attempt to fabricate natural cellulose material using hydrodynamic as well as acoustic cavitation. The cellulose material having initial size of 63 micron was used for the experiments. 1% (w/v) slurry of cellulose sample was circulated through the hydrodynamic cavitation device or devices (orifice) for 6 h. The average velocity of the fluid through the device was 10.81 m/s while average pressure applied was 7.8 kg/cm2. Cavitation number was found to be 2.61. The average particle size obtained after treatment was 1.36 micron. This hydrodynamically processed sample was sonicated for 1 h 50 min. The average size of ultrasonically processed particles was found to be 301 nm. Further, the cellulose particles were characterized with X-ray diffraction (XRD) and differential scanning calorimetry (DSC) to see the effect of cavitation on crystallinity (Xc) as well as on melting temperature (Tm). Cellulose structures consist of amorphous as well as crystalline regions. The initial raw sample was 86.56% crystalline but due to the effect of cavitation, the crystallinity reduced to 37.76%. Also the melting temperature (Tm) was found to be reduced from 101.78°C of the original to 60.13°C of the processed sample. SEM images for the cellulose (processed and unprocessed) shows the status and fiber-fiber alignment and its orientation with each other. Finally cavitation has proved to be very efficient tool for reduction in size from millimeter to nano scale for highly crystalline materials

Room temperature synthesis of crystalline CeO<SUB>2</SUB> nanopowder: advantage of sonochemical method over conventional method

In the present study, nano-sized ceria (CeO2) powders were prepared using conventional and sonochemically assisted precipitation method, without any stabilizers, using cerium nitrate as a starting material and sodium hydroxide as a precipitating agent. The synthesized ceria powders were characterized by XRD, TGA and SEM to determine crystallite size, % crystallinity, thermal weight loss and shape respectively. It was found that the crystallite size obtained in both the synthesis methods were below 30 nm. It was also found that sonochemical synthesis method is energy efficient method saving more than 92% of energy as compared to that utilized by the conventional synthesis method. There was also a significant reduction in the reaction duration

Ultrasound assisted green synthesis of zinc oxide nanorods at room temperature

Nanostructured ZnO (without stabilizers) has been synthesized using conventional (non-ultrasound i.e. NUS) as well as sonochemically assisted (US) synthesis method. Zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and sodium hydroxide (NaOH) have been used as raw materials (synthesis precursors). Zinc nitrate hexahydrate reacts with sodium hydroxide at room temperature (35 ± 2°C) to form ZnO powder. It is found that equilibrium conversion occurred in a shorter time in sonochemically (US) assisted method when compared to conventional (NUS) method. The ZnO powders synthesized by both the methods have shown to have nanometric-sized crystallites. It was found that the crystallite size of the sonochemically (US) synthesized ZnO and conventionally (NUS) synthesized ZnO are 23 ± 1 nm and 32 ± 1 nm respectively. The FTIR spectra analysis confirms the occurrence of the reaction to form Zinc Oxide by both NUS and US methods. Needle shaped structures agglomerated in the forms of bundles were also found in SEM micrographs. It was found that sonochemical synthesis method have saved more than 90% of energy utilized by conventional synthesis method along with the reduced in the reaction duration by 110 minutes

An Energy Efficient Sonochemical Selective Oxidation of Benzyl Alcohols to Benzaldehydes by Using Bio-TSIL Choline Peroxydisulfate

The present work deals with effective combination of ultrasonication (US) and biodegradable oxidizing task specific ionic liquid (bio-TSIL) choline peroxydisulfate monohydrate (ChPS·H₂O) for the selective oxidation of alcohols to aldehydes/ketones. The reactions were also conducted by using a thermal heating method (TH), and the comparative studies are provided to understand the effectiveness of the ultrasound process; it was observed that the use of ultrasound significantly reduces the reaction time from 30 to 5 min. Also, a substantial energy saving (>86%) was observed when the US method (0.125 kJ/g) was compared with the TH method (0.958 kJ/g). Bio-TSIL ChPS in water as an oxidant is found to be advantageous, as it is synthesized from biodegradable and nontoxic raw materials. Incorporation of an ultrasonic energy source along with the use of biodegradable raw materials for bio-TSIL makes the process not only green but also energy efficient

Acoustic Cavitation as a Novel Approach for Extraction of Oil from Waste Date Seeds

This work deals with the extraction of date seed oil using an acoustic cavitation. The process parameters such as sonication (extraction) time, power dissipation, operating temperature, and solvent to date seed ratio have been optimized on the basis of extracted oil yield. The obtained results have been compared with the frequently used extraction methods (such as maceration and Soxhlet extraction method). The highest extraction efficiency was found at a solvent (hexane) to seed ratio of 5, applied rated power of 30% of 750 W (actual dissipated power is 2.98 W), ultrasound treatment time of 45 min, and at a temperature of 20 °C. It was observed that as ultrasonic power dissipation increases the oil extraction yield also increases and declines with an increase in temperature. These results are attributed to only physical effects of cavitation occuring onto the surface of the date seeds which enhance the permeability of the solvent into the plant tissues due to the formation of cracks, crevices, and microfractures onto seed surfaces. A comparison of field emission scanning electron microscopy (FE-SEM) images of fresh date seed and ultrasonically treated date seed indicated the development of cracks, crevices, and microfractures onto seed surface of date seed which results in the cell walls disruption. However, the cavitation-assisted oil extraction has reduced the environmental impact and lessened the time and energy intensive process as it was performed at room temperature