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Highly efficient and environmentally friendly carboxylated cellulose silica hybrid adsorbents were prepared by combining the advantages of cellulose and silica. The surface property and chemical composition of produced cellulose silica hybrid adsorbents were extensively characterized via different techniques. The results indicated that silica particles were densely deposited on the surface of composite adsorbents. Because of their porous structure and large specific surface area, the carboxylated cellulose silica hybrid adsorbents demonstrated a high capacity of methylene blue (MB) adsorption, exceeding 990 mg·g-1. This adsorption capacity was more than 45% higher than that of carboxylated cellulose adsorbent. The cellulose silica hybrid adsorbents were able to maintain an MB adsorption efficiency of up to 70% even after undergoing five cycles. This study developed cellulose silica hybrid adsorbents for wastewater treatments. High adsorption capacity and stability make them sustainable and cost-effective alternatives to traditional adsorbents.

Toxic organic dyes present in wastewater should be removed before discharge. In this study, TEMPO-oxidized, regenerated cellulose beads were prepared using a simple falling ball technique for cationic methylene blue (MB) removal. The obtained cellulose beads were characterized using various analytical techniques. The results indicated that TEMPO-oxidized cellulose beads displayed porous structures with high content of carboxylic acid groups. Thus, the negatively charged cellulose beads can effectively adsorb cationic MB with an adsorption capacity of 495 mg/g at a starting concentration of 100 mg/L. This simple one-step adsorption process achieved near-complete MB removal at pH 7, indicating strong electrostatic interactions between cationic MB and negatively charged oxidized cellulose beads. The experimental data can be well described by the Langmuir isotherm model and the Pseudo-second-order model. The fabricated cellulose beads exhibit great potential for practical application in dye removal from wastewater.

Corn stalk rind (CSR) was treated with Trametes hirsuta lg-9 and then refined into pulp. The biotreatment resulted in loss of paper strength and brightness, but energy consumption during refining (ECR) was reduced. Meanwhile, multiple linear regression was carried out, for which ECR served as the dependent variable, and the yield and infrared relative absorbance intensities at 3414 cm-1 and 1653 cm-1 of the biotreated CSR served as independent variables. Results showed that the determining parameters of the biotreated CSR may be used to predict the ECR. In this work, delignified corn stalk pith (CSP) was added to aspen alkaline hydrogen peroxide mechanical pulp (APMP). The CSP enhanced the strength properties of the aspen APMP and inhibited yellowing. The biomechanical pulping of CSR has the potential to produce a low-cost green pulp, and the delignified CSP can serve as a pulp additive.

Recombinant strain Xz6-1 was constructed by the protoplast fusion technique with the goal of endowing it with the ability to efficiently degrade pentachlorophenol (PCP). This compound was considered as a representative of possible compounds that can be obtained during the bleaching of pulp for papermaking. The potential of Xz6-1 and Pseudomonas putida to treat PCP synthetic wastewater was explored. The majority of PCP was removed within the first 20 h; two degradation curves were obtained that followed first-order reaction kinetics. The kinetics data revealed that the rate constant for degradation of PCP for Xz6-1 was 0.063 h-1, a value that was over 50% greater than that of Pseudomonas putida (0.040 h-1). Aerobic granular sludge was highly fortified with Xz6-1 and Pseudomonas putida to provide PCP degradability improvements of 180.9% and 98.3%, respectively, relative to the original sludge. All results demonstrate that the protoplast fusion technique is an effective approach to construct a high-activity chlorophenol-degrading strain.

To demonstrate the feasibility of bioaugmentation in enhancement of the biodegradation of pulping effluent, aerobic sludge was intensified with superior mixed flora. The differences between intensified aerobic activated sludge and original sludge were compared. The results showed that the chemical oxygen demand (COD) of pulping effluent treated with the intensified sludge dropped to a much lower level compared with the original sludge, which indicated that the biodegradability of sludge was enhanced by bioaugmentation. The growth kinetics of the sludges were established. The growth rate Vmax of the intensified sludge was elevated from 7.8×10-3 to 7.1×10-3, while the saturation constant Ks decreased from 0.33 to 0.21 after bioaugmentation. In addition, the degradation kinetics showed that the equation coefficient of sludge increased from 4.6×10-3 to 6.4×10-3, confirming the intensification of biodegradation as a result of bioaugmentation.

Statistically based experimental designs were used to construct a mixed-culture community for maximizing the chemical oxygen demand (COD) degradation of pulping effluents by the use of six different strains, i.e., Agrobacterium sp., Bacillus sp., Enterobacter cloacae, Gordonia, Pseudomonas stutzeri, and Pseudomonas putida. Significant effects of single and mixed strains on COD degradation were quantified first by applying a fractional factorial design (FFD) of experiments, and four strains were selected as the main driving factors in the process of biodegradation of effluents. Then the Steepest Ascent method was employed to approach the experimental design space, followed by an application of response surface methodology to further optimize the proportion of cell concentration for different strains in pulping effluent. A quadratic model was found to fit COD removal efficiency. Response surface analysis revealed that the optimum levels of the tested variables for the degradation of COD, and optimized cells concentrations (OD600) of four strains in mixed-culture community were 0.35 Agrobacterium sp., 0.38 Bacillus sp., 0.43 Gordonia sp., and 0.38 P. putid., respectively. In a confirmatory experiment, three test runs were performed by using the optimized conditions, and a COD removal efficiency of (65.3 ± 0.5)% was observed, which was in agreement with the prediction.

Carbon dots have good dispersion capability, strong visible fluorescence, low toxicity, and photo-induced accepting and donating abilities. Carbon dots were obtained from biomass bacterial cellulose (BC) via one-step hydrothermal carbonization. Effects of hydrothermal time and temperature on the microstructure, fluorescence, and excitation wavelength dependent photoluminescence (PL) behavior were explored for the prepared carbon dots. The results showed that the carbon dots obtained directly from the BC (C dots) had small particle sizes (2.0 to 3.0 nm) and green luminescence behavior. Conversely, the N-doped carbon dots (N-C dots) exhibited more uniform and smaller particle sizes (approximately 1.0 nm), strong blue luminescence, acceptable fluorescence lifetime, and good stability in a wide range of pH values (2.0 to 10.0). Thus, carbon dots could serve as a fluorescent material used in high performance optical cellular imaging and highly sensitive bacterial detection. [ABSTRACT FROM AUTHOR]

Corncob, a renewable biomass waste, has been successfully explored as a low-cost crude carbon source to prepare controlled morphology, and result in higher value-added carbons through a ZnCl2/NaCl treatment and direct pyrolysis process. The synthesis route is simple, green, and results in carbons with different morphology and porous structures by varying the ratio of the eutectic salt ZnCl2/NaCl. Moreover, the adsorption capacities of different carbon materials for formaldehyde and butyraldehyde were tested further. It was demonstrated that NaCl and ZnCl2 could be utilized as a mesopore template, and as a micropore activation agent for carbon materials, respectively. Although the mesopores can provide a fast diffusion channel, and the micropores can enhance adsorption ability, the specific surface area originating from the mesopores was proportional to the amount of butyraldehyde adsorption, and the specific surface area of the micropores was beneficial to the amount of formaldehyde adsorption taking place. The adsorption isotherms follow Langmuir and pseudo first-order kinetic modeling. Additionally, the whole process belongs to physical adsorption. [ABSTRACT FROM AUTHOR]

The suitability of specific Sudanese agrowastes, sorghum straw, bagasse, and their 50% blend, were investigated for pulp and papermaking initiatives. A chemical analysis of sorghum straw and bagasse revealed levels of cellulose, lignin, hemicellulose, and ash for sorghum straw and bagasse that signalled a suitable relation to traditional wood feedstocks for pulping and papermaking applications. Moreover, the pulp yield and viscosity of sorghum straw were lower and higher, respectively, compared with the bagasse and the blend. More specifically, the papers obtained from bagasse showed better physical properties (tensile strength, tearing index, bursting index, and folding) compared to those of sorghum straw and the blend. The surface morphologies of the papers were analysed using scanning electron microscopy (SEM), which showed that the fibres had a long, swollen, compact, and closely packed arrangement and were more homogeneous and well-blended for the bagasse compared with the pure sorghum straw and the 50% blend. [ABSTRACT FROM AUTHOR]