Research Articles

A broad-spectrum substrate-imprinted adsorption and crosslinking double immobilized pectinase (SDP) was prepared using a universal modified pectin obtained through enzymatic hydrolysis as the imprinting substrate. Its structure was characterized by infrared spectroscopy, circular dichroism, and scanning electron microscopy. The results showed that 1) cross-linking increased the Schiff base in SDP, 2) immobilization barely changed the secondary structure such as α-helix and β-sheet of SDP, and 3) adhesives were evenly distributed on the surface after immobilization. Studies on the enzymatic properties of SDP showed that the substrate imprinting significantly improved heat resistance and neutralization resistance of SDP. For example, the relative activity of SDP at 35 to 75 °C and at pH 4.4 to 6.5 was 5% and 15% more than that of the adsorption and crosslinking double immobilized pectinase (DP), respectively. In addition, after 8 cycles of use, the relative enzyme activity of SDP still reached 39.5%. Moreover, use of SDP decreased the cation demand in whitewater by 10% compared with DP. Overall, the use of a broad-spectrum substrate for imprinting to obtain SDP provides a new idea and method for using pectinase in in complex systems such as juice clarification and wastewater treatment.

Kenaf was replaced by various amounts of empty fruit bunch (EFB) in natural rubber latex foam (NRLF). Five different compositions of kenaf/EFB (7/0, 5/2, 3.5/3.5, 2/5, 0/7 phr) were prepared by using the Dunlop method. The comparison of tensile properties, morphology, foam density, compressive strength, hardness, swelling, compression set, and accelerated aging of natural rubber latex foam (NRLF) were studied. The tensile strength, modulus at 100% (M100), foam density, compressive strength, hardness, and compression set decreased with increasing EFB loading. However, the elongation at break and swelling percentage of NRLF increased as the content of EFB decreased. Morphological studies showed that a higher amount of EFB weakened the interaction between EFB and NRLF matrix and increased the formation of cell windows. The EFB-filled NRLF also showed better tensile retention compared to kenaf filled NRLF.

Experiments were conducted in pots to study the effects of 2.5% rice straw and 1% rice straw ash on rice growth and bacterial community abundance in areas mined for heavy rare earth elements. The results showed that the incorporation of rice straw improved the pH value of soil, reduced the α-diversity of the soil bacterial community, improved the abundance of Proteobacteria and Firmicutes; reduced the abundance of Acidobacteria, Nitrospirae, etc.; reduced the abundance of Candidatus Solibacter, Syntrophobacter, Haliangium, Candidatus Koribacter; and increased the abundance of Ideonella, Anaeromyxobacter, Roseomonas, Clostridium sensu stricto 10, and Geobacter. The decrease in the abundance of beneficial bacteria, Acidobacteria and Nitrospirae, inhibited the growth of the rice; reduced the dry weight of the rice roots, the shoots, and the grains, and increased the concentration of rare earth elements in the rice. Returning 1% rice straw ash to the field had little effect on the diversity and richness of the bacterial community in areas mined for heavy rare earth elements. Also the returned rice straw had little effect on the rice growth, the dry weight of the roots, the shoots, the grains, and the concentration of rare earth elements in these parts of the rice.

The relationship between the types of pulp, the tissue making technologies, and shelf price of bath tissue was evaluated for the North American market. Twenty-four market tissue samples (representing approximately 80% of the current market offering) were sourced and analyzed along with their nationwide price information. Pulp composition, drying technologies, market share, sustainability advertising, and tissue properties were evaluated. Tissue properties, including softness, ball burst strength, water absorbency, density, tensile strength, and tensile modulus were measured. Among all the drying technologies, creped through-air dry (CTAD) and creped through-air dry belt (CTADB) seemed to improve tissue softness most. The UCTAD maximized tissue bulk by drying the tissue web solely using a through-air (TAD) cylinder. Tissue samples with freeness between 575 to 650 mL seemed to have their properties improved more significantly through advanced drying technologies. It was found that the retail prices of these bath tissues were directly related to softness, bulkiness, water absorbency, and basis weight. A mathematical model was conducted to predict the retail price of bath tissue (based on product performance and attributes). This paper also identified the effect of “sustainability” on the retail price.

The use of freely suspended cells of microalgae culture to treat wastewater is of current global interest because of their effective photosynthetic uptake of pollutants, carbon dioxide sequestration, and biomass production for desirable high value-products. Biomass immobilization is a promising option to overcome the harvesting problem that is encountered when using free-cells upon completion of the wastewater treatment process. In this study, Nannochloropsis sp. cells were immobilized in sodium alginate beads to eliminate the harvesting limitation. The microalgal beads were further cultivated in treated palm oil mill effluent (TPOME) for removal of chemical oxygen demand (COD). The effect of POME concentration on COD removal and microalgal cells growth was investigated, respectively. It was found that the maximum biomass concentration of 1.23 g/L and COD removal of 55% from 10% POME were achieved after 9 days. An increment of POME concentration did not cause any improvement to the treatment efficiency due to the inhibitory effect of high initial COD of POME on the biomass concentration and was further responsible for low COD removal. The immobilized cells showed a systematic growth, demonstrating that the beads are biocompatible as immobilization carrier. In conclusion, the immobilized microalgal cells could be a viable alternative technology system for POME treatment as well as biomass production.

Physical proprieties of particleboard, medium-density fiberboard, and wood-plastic composite board were studied by measuring the thickness and weight changes during repeated humidity cycling (RHC). The thickness stability, moisture absorbing capacity, and internal band strength of the control and treated specimens were measured for the three tested materials. The wood-plastic composite board showed the greatest stability, with only small changes in thickness and weight. Temperature is a key component of RHC treatment, with greater thickness changes after six cycles at 50 °C than after nine cycles at 20 °C. Compared with the control materials, the thickness stability of RHC-treated materials was decreased by 23.7 to 31.8%; RHC decreased the internal bond strength of specimens 22 to 23% for particleboard and medium-density fiberboard and 2.15% for wood-plastic composite board. Overall, thickness stability and internal bonding strength of the tested materials were highly correlated.

The aim of this work was to investigate the possibility of processing forest residues by chemical delignification preceded by mild steam explosion. The focus was on using soda pulping, due to its simplicity. Kraft cooking was used for comparison to improve the understanding of the separation of the complex yet promising resource. The raw material consisted of chipped branches, bark, and twigs of mixed hardwood and softwood. Analysis of the raw material proved to be challenging due to the presence of a substantial fraction of extractives. Analysis of the pulps showed that the forest residue delignification was faster than that of wood. The effects of steam explosion were evaluated with the help of composition analysis, gel permeation chromatography (GPC) for the molecular weight of lignin, and NMR for the changes in its structure. The impact of steam explosion was found to be limited, possibly due to the relatively small size of the material.

Lumber mills generate a huge volume of residues, with tree bark and saw shavings being main contributors. A small amount of this material is burned for energy generation, though most of it is left on the sawmill grounds or dumped in sanitary landfills, thus presenting a huge environmental issue. This study deals with the application of eucalyptus bark and saw shavings for the manufacturing of oriented strand board (OSB). Four types of panel compositions where studied: 25%, 50%, 75%, and 90% of bark content; 10% percent of shavings for all of them, and a variable content of pine strands. The adhesive was phenol formaldehyde at 6% related to the dry mass of the components. Because an important characteristic of OSB panels is their response to swelling, a 1% of paraffin emulsion was added to seal the particles. The results showed that only the 90%-bark panel could meet OSB standard prescriptions as a type 1 “dry environment application”.

Spindleless lathes have shown great potential for the efficient conversion of small native forest logs in Australia. However, a major impediment to the further commercial adoption of this processing approach for native forest small-diameter logs is the absence of reliable and available data on the quantities of logs possibly available and suitable for this purpose. This study undertaken in hardwood and white cypress pine (Callitris glaucophylla) native forests and at sawmills in Queensland, Australia, demonstrated that there are potentially substantial quantities (up to 10.5 m3 per hectare of Crown native hardwood, 14 m3 per hectare of private forest hardwood and 75,000 m3 per year of Crown white cypress pine) logs suitable for spindleless lathe rotary veneer processing. However, access to and utilization of these logs will depend on many factors including accommodating Government policies and log supply agreements; potential alterations in the code of practice for native forest harvesting, silviculture, tree marking and sales practices; diversion of logs from other uses; and development of appropriate log specifications.

In recent years, medium density fiberboard has been extensively used for furniture production. Often it is painted or coated using a PVC film in modern production, after the surfaces are formed via CNC machining. The surface roughness of medium density fiberboard used in this way is very important for the quality of the surface. In previous studies, the effects of the cutting parameters of a CNC router on the surface roughness of medium density fiberboard were investigated using laboratory test samples. The present study focused on the effects of certain cutting parameters of a CNC router on the surface roughness of real size test samples. In addition, the energy consumption and total processing time of the CNC router were investigated, in relation to the cutting parameters. Three different spindle speeds (8000 rpm, 12,000 rpm, and 16,000 rpm) and feed rates (3 m/min, 5 m/min, and 7 m/min) were used. According to the data obtained, it was determined that as the spindle speed increased, the surface roughness decreased, and the total energy consumption increased. However, as the feed rate increased, the surface roughness increased, and the total energy consumption decreased.