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Modifying natural polymers with silicones gives new possibilities for packaging products and waste management. In this study, the innovative papers produced were altered following the reaction of polysaccharides and organosilicon compounds. The susceptibility of the studied material to biodegradation caused by a brown-rot fungus was assessed. Strength properties by tensile strength and dynamic mechanical analysis and hydrophobic properties by water uptake test and water contact angle analysis were evaluated. Moreover, elemental analysis by ICP method was controlled. The durability against fungi and the hydrophobic properties were increased by the modification. The fungal decay resistance of the silanized paper was reduced by water storage, which allows for managing paper waste. Cellulose-based paper treated with starch-modified methyltrimethoxysilane showed potential as a packaging material due to its reduced water uptake. Possible application areas could be corrugated boxes, cellulose thermoformed products for electronics, and food packaging. However, the water-repellent effect is limited to short-term exposure in humid conditions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Over 64 billion paper-plastic laminate (PPL) coffee cups are consumed between the United States and Canada annually, the majority accumulating in landfills due to a hydrophobic plastic inner-lining. Recycling can mitigate environmental damage and provide economic value from repurposed products. We found that standard repulping methods were insufficient to separate fiber from plastic due to the low intensity of treatment. To increase process intensity, we mechanically refined shredded PPL coffee cups and Kraft eucalyptus sheets (control) at 2%, 3%, and 4% consistencies with three passes to determine the energy required to separate fibers from plastic and the effects on fiber quality. 2% and 3% consistency PPL cups measured under 40 kWh/tonne of input material for one refiner pass and ∼ 80 kWh/tonne for 4% consistency PPL cups. Recovered fiber fraction totaled 87.7%, 85.3%, and 80.5% of input mass of Kraft eucalyptus and 72.3%, 72.6%, and 79.6% of input mass of PPL cups at 2%, 3%, and 4% consistency, respectively. Fines content of PPL cups jumped from 8% pre-refining to ∼ 30% post-refining while Kraft eucalyptus fibers were unaffected, suggesting that breaking the plastic-fiber bonds results in fines generation. Mean fiber length of PPL cups slightly decreased with consistency and tensile strength improved. Freeness decreased with consistency only in PPL cup samples. These results demonstrate a low energy requirement to effectively separate fiber and plastics in PPL cups as well as minimal impact on fiber quality using existing refining technology, and provides an estimate of the financial costs of local recycling efforts., (Copyright © 2021. Published by Elsevier Ltd.)

Paper mill sludge (PMS) raises critical environmental issues due to its disposal problem, but its high sugar content and well-dispersed structure make it a great feedstock for biochemical production. The technical feasibility of integrating cellulase enzyme production into lactic acid (LA) fermentation from PMS was investigated in this study. The low ash content of PMS suggests a great potential for cellulase production. The enzyme produced using PMS without any treatment gave an activity of 7.8 FPU/ml, a performance comparable to the commercial enzyme, Cellic CTec 2. The LA yield from PMS with in-house enzyme was 64.7% and 73.7% at the enzyme loading of 10 and 15 FPU/g-glucan, respectively. The LA obtained was optically pure L- isomer with over 99% purity. The optimal condition of LA production by Bacillus coagulans was found to be 50 °C and pH 5.3 (with 50 g/L CaCO 3 ). The nutrient effect of yeast extract (YE) and corn steep liquor (CSL) was substrate dependent, and CSL could substitute YE as an inexpensive nutrient when using PMS as a substrate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Oxygen blown high-temperature gasification constitutes an opportunity for chemical recycling of plastic wastes. This article summarizes the results from comparative tests of combustion and gasification of two complex plastic wastes: a plastic reject (PR) from processing recycled paper and an automotive shredder residue (ASR). Calculated gasification efficiencies corresponded to about 80% and 60%, respectively. Gasification resulted in lower yields of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) compared to direct combustion. A two-stage process, including gasification followed by syngas combustion, reduced the emissions of HCl and PCDD/F in the flue gas to <1.4% and <0.2%, respectively, compared to the levels from direct combustion of the PR feedstock. Most of the PCDD/F (>99%) was captured along with particulate matter (soot) during gasification. The contribution to the toxic concentration of PCDD/F was mainly from the PCDF congeners. Fly ash particulate matter from ASR combustion contained a significant proportion of zinc, which thus constitutes a great potential for use in zinc recycling., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Humic acid (HA) in compost has received widespread attention for its high redox activity, which can mediate the degradation of organic pollution and the passivation of heavy metals in the environment. Hyperthermophilic composting (HTC) can accelerate HA formation. However, few studies have examined whether and how the structures of different organics affect the formation of the HA and HA redox structure at the molecular level in HTC. Detailed molecular information and the redox capacity (electron transfer capacity, ETC) of HA in HTC and thermophilic composting (TC) were characterized using pyrolysis gas chromatography/mass spectrometry and the electrochemical method, respectively. HTC promoted the formation of redox structure, leading to the improvement of the ETC of HA. Aromatics and N-containing compounds were mainly derived from protein components, and the rate at which they were transferred into HA was accelerated in HTC, while the relative abundance of lipids decreased. Partial least squares regression and correlation analysis demonstrated that protein-derived compounds were the key factor determining the HA redox capacity. Finally, partial least squares path modeling suggested that the influence mechanism of protein-derived structures on HA redox capacity might differ in HTC and TC. HTC may promote the relative abundance of N-containing components into the C-skeleton and accelerate the accumulation of the aromatic products, thereby improve the HA redox capacity. These findings provided new insight into how the redox capacity of the HA in compost could be improved and how compost products could be prepared for use in environmental remediation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Catalytic conversion of xylose and the hemicellulose fraction of waste biomass to furfural is important for the valorization of waste lignocellulose. Here, a clean and efficient catalytic system consisting of sulfonated carbon microspheres catalysts and γ-valerolactone was developed for the upgrading of xylose and waste lignocellulose to the furfural in one-pot. Sulfonated carbon microspheres (CCoS) with Brønsted and Lewis acid sites were prepared to yield furfural. The mesoporous structures were facilitated by introduction of Co element in xylose hydrothermal process, and the density of Brønsted acid sites were improved by the sulfonation. The furfural yield from xylose reached 75.12% using CCoS as catalyst at 170 °C for 30 min in a γ-valerolactone/water (17/3 v/v) solvent. As typical Brønsted acid, the SO 3 H groups on the surface of CCoS catalyst is essential for catalytic dehydration xylose to furfural. Additionally, the mesoporous structures of CCoS improved the mass transfer in the furfural production process. The catalytic system was applied in the conversion of real biomass (including corncob, corn straw and Eucalyptus sawdust) to evaluate the possibility of application. These three biomass species all reached excellent furfural yields, which were more than 70%. This work provided a catalytic strategy for effective conversion of xylose and biomass to furfural., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A challenge of today's industry is to transform low-value side products into more value-added materials. The acid-catalyzed conversion of hemi(cellulose) to platform chemicals in green chemical/fuel production and biorefinery yields large formation of insoluble byproduct called humin. Herein, humin obtained from dehydration of glucose was transformed into a novel class of effective carbonaceous solid acid catalyst for the first time via low-temperature pyrolysis followed by sulfonation. A range of preparation conditions were investigated, and the structure-function relationships of the resulting catalysts were also discussed based on the analysis of structure and composition. Comparing with the glucose-derived carbon catalyst, the humin-derived catalyst has substantially larger surface area and higher SO 3 H density, which enable it to display higher catalytic activity and efficiency not only in esterification of levulinic acid and n-butanol (yield = 95.0%, 373 K), but also in hydroxyalkylation/alkylation of 2-methylfuran and furfural (yield = 64.2%, 323 K). Additionally, the catalyst could be repeatedly employed for at least four cycles without obvious deactivation, exhibiting good reusability. This work provides a green method to convert humin byproduct into economic and eco-friendly solid acid catalyst and may contribute to a holistic approach for biomass utilization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Application of thermophilic composting (TC) is limited due to poor efficiency and long composting period. Hyperthermophilic composting (HTC) could effectively overcome this defect. Here, the transformation of humic acid (HA) in both HTC and TC was characterized and compared to investigate the roles of HTC toward accelerating the formation of HA. In HTC, the highest temperature was 96.6 °C, and the hyperthermophilic and thermophilic phases exceed 18 days. The degree of polymerization (DP) in HTC increased to 1.27 on day 27, while it only increased to 1.15 at the end of TC. The elemental composition of the HA in HTC showed higher O atomic content (36.3%) and lower C/N atomic ratio (6.5) compared with TC. These changes indicated that HTC could significantly accelerate oxidized and polycondensed reactions for HA formation, which resulted in the shortening of composting period to 27 days. The maximum fluorescence intensity (F max ) of humic-like components were achieved faster in HTC (F max  = 1649.9) than in TC (F max  = 1316.9), implying that HTC promoted the polycondensation of small molecular components to form HA with larger molecular weight and higher degree of aromatization. Two-dimensional FTIR correlation spectroscopy (2D-FTIR-COS) analysis demonstrated that HTC prevented the HA precursor from condensing before it was deeply oxidized, and increased the content of small molecules rich in carboxyl moieties. Based on the evolution of the molecular structure of HA, the level of oxidation of HA precursors was a key factor to determine the degree of polymerization and the degree of HA humification., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Waste biomass derived heterogeneous catalyst is an excellent alternative to chemically synthesized catalysts. In this work, calcined Tectona grandis leaves were proposed as an eco-friendly, renewable and low cost heterogeneous base catalyst. The prepared catalyst was examined by FTIR, XRD, XPS, SEM, EDX, TEM, TGA, BET and Hammett indicator test. The catalyst has an appealing nature towards various chemical transformations due to its basic surface sites provided by alkali and alkaline earth metals. The efficiency of the catalyst was successfully investigated by its application in biodiesel production. The products were confirmed by 1 H and 13 C NMR. 100% FAME conversion was attained using a catalyst loading of 2.5 wt% under optimized reaction parameters. The catalyst was further explored for Knoevenagel condensation reaction, in which it showed its effectiveness and recyclability towards the formation of benzylidenemalononitrile derivatives of aryl aldehydes. Thus, it is a potential 'green catalyst' derived from waste biomass without any addition of chemicals that can replace the industrial base catalysts used for biodiesel production and Knoevenagel reaction and makes the protocol environmentally benign., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Nanocellulose has achieved an inimitable place and value in nano-materials research sector. Promising and exclusive physical, chemical and biological properties of nanocellulose make it an attractive and ideal material for various high end-user applications. Conventionally, the base material for nanocellulose i.e. cellulose is being extracted from various lignocellulosic raw materials (like wood, agro-industrial-residues, etc.) using pulping followed by bleaching sequences. As an alternate to lignocellulosic raw materials, waste paper also showed potential as a competent raw material due to its abundant availability and high cellulosic content (60-70%) with comparatively less hemicelluloses (10-20%) and lignin (5-10%) without any harsh treatments. The production yields of nanocellulose were reported to vary from 1.5% to 64% depending upon the waste papers and treatments given. The diameters of these nanocelluloses were reported in the range of 2-100 nm and crystallinity range around 54-95%. Thermal degradation of waste paper nanocellulose was varied from 187 °C to 371 °C. Although these properties are comparable with the nanocellulose obtained from lignocellulosic raw materials, yet waste paper is an underutilized source for nanocellulose preparation due to its ordinary fate of recycling, dumping and incineration. In the sight of necessity and possibility of waste paper utilization, this article reviews the outcomes of research carried out for preparation of nanocellulose using waste paper as a source of cellulose. There is a need of sincere investigation to convert this valuable waste to wealth i.e. waste papers to nanocellulose, which will be helpful in solid waste management to protect environment in economical way., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Each year millions of tons of agricultural wastes are produced, however, not well utilized in China. Considering the economic development and environmental protection, the valorization of these wastes is increasingly necessary and important. Here we used p-toluenesulfonic acid hydrolysis followed by mild disk grinding for on-farm valorization of wheat straw (WS) and their pulping solid residue (waste wheat straw, WWS) to produce lignocellulosic nanofibrils (LCNF). Alkaline peroxide post-treatment was further conducted to obtain purified lignocellulosic nanofibrils (P-LCNF) with lower lignin content and thinner diameters. The raw materials and resulting LCNF and P-LCNF were investigated in each process for their chemical component, crystal structure, morphology, and thermal properties. Interestingly, although WS fiber had higher lignin content than WWS fiber, the WS fiber with lower ash content resulted in LCNF and P-LCNF with smaller height and lower thermal stability, but higher crystallinity and higher specific surface area. Higher ash content in WWS fiber protected cellulose and lignin from depolymerization and degradation, respectively, which endowed LCNF and P-LCNF with entangled network structure. Overall, this study indicated that the low-temperature fractionation process on WS and WWS fibers could yield cellulose nanomaterials with potential value-added application and achieve the efficient utilization of agricultural wastes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Biochar was produced from anaerobically digested dairy manure under different processing temperatures (300, 600 and 1000 °C). The process could transform the biomass waste to high-value-added biochar products in high efficiency as well as reduce the manure biological pollution to the environment. By the results of thermogravimetric analysis (TGA) two kinetic models (FWO and Starink) were used to evaluate the activation energy. The biochar was studied for its surface area and pore size, chemical functionality, and crystalline structure by BET analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). More porous and channel structures were observed under higher temperature and inert gas atmosphere, as characterized by scanning electron microscopy (SEM). The biochar with tunable physicochemical properties that was produced under different temperatures may be used for soil amendment or other fields., (Copyright © 2018. Published by Elsevier Ltd.)

Pulp and paper mills are indispensable for any nation as far as the growth of the nation is concerned. Due to fast growth in population, urbanization and industrialization, the demand and consumption of paper has increased tremendously. These put high load on our natural resources and force the industry to look for alternative raw material. Rice straw is a lignocellulosic material abundantly available in wood short countries like China, India, Bangladesh, etc. and can be used as raw material for this industry. Open burning of rice straw releases noxious green house gases to the air and poses serious threats to global air chemistry and human health. So, it is a dual benefit option (for farmers and industries) to use rice straw as a raw material in pulp and paper industry. Organosolv pulping using acids are the prominent choices of researchers to convert this residue into valuable pulp but in developed countries only. Developing world favours the soda and soda-AQ processes as these are economical. As a virtue of less lignin content in comparison to wood, rice straw requires less harsh conditions for cooking and can be easily pulped. Bleaching is a crucial step of paper making but also responsible for causing water pollution. Many studies revealed that during the process more than 500 chlorinated compounds are released that are highly toxic, bioaccumulative and carcinogenic in nature. Most of the industries over the globe switch on to the elemental chlorine free short sequence bleaching methods using chlorine dioxide, hypochlorite and hydrogen peroxide. This paper presented the effective need of ecofriendly, economically reliable pulping and bleaching sequences in case of rice straw to eliminate the problems of chlorinated compounds in wastewater of paper mills. Such approach of using waste as a raw material with its environmentally safe processing for making paper can prove to be valuable towards sustainable growth., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Sewage fine sieved fraction (FSF) is a heterogeneous substrate consisting of mainly toilet paper fibers sequestered from municipal raw sewage by a fine screen. In earlier studies, a maximum biodegradation of 62% and 57% of the sewage FSF was found under thermophilic (55°C) and mesophilic (35°C) conditions, respectively. In order to research this limited biodegradability of sewage FSF, this study investigates the biodegradation of different types of cellulosic fibers-based hygiene papers including virgin fibers based toilet paper (VTP), recycled fiber based toilet paper (RTP), virgin pulp for paper production (VPPP) as a raw material, as well as microcrystalline cellulose (MCC) as a kind of fiberless reference material. The anaerobic biodegradation or digestibility tests were conducted under thermophilic and mesophilic conditions. Results of the experiments showed different biomethane potential (BMP) values for each tested cellulose fiber-based substrate, which might be associated with the physical characteristics of the fibers, type of pulping, presence of lignin encrusted fibers, and/or the presence of additive chemicals and refractory compounds. Higher hydrolysis rates (Kh), higher specific methane production rates (SMPR) and shorter required incubation times to achieve 90% of the BMP (t90%CH4), were achieved under thermophilic conditions for all examined substrates compared to the mesophilic ones. Furthermore, the biodegradability of all employed cellulose fiber-based substrates was in the same range, 38-45%, under both conditions and less than the observed FSF biodegradability, i.e. 57-62%. MCC achieved the highest BMP and biodegradability, 86-91%, among all cellulosic substrates., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The aim of this paper is to analyse the effects of the presence of printed electronics on the paper waste streams and specifically on paper recyclability. The analysis is based on a case study focussed on envelopes for postal and courier services provided with these intelligent systems. The smart printed envelope of the study includes a combination of both conventional (thin flexible batteries and resistors) and printed electronic components (conductive track layout based on nanosilver ink). For this purpose, a comparison between envelopes with and without these components (batteries, resistors and conductive track layouts) was carried out through pilot scale paper recycling tests. The generation of rejects during the recycling process as well as the final quality of the recycled paper (mechanical and optical properties) were tested and quantitatively evaluated. The results show that resistors are retained during the screening process in the sieves and consequently they cannot end up in the final screened pulp. Therefore, mechanical and optical properties of the recycled paper are not affected. Nevertheless, inks from the conductive track layouts and batteries were partially dissolved in the process water. These substances were not totally retained in the sieving systems resulting in slight changes in the optical properties of the final recycled paper (variations are 7.2-7.5% in brightness, 8.5-10.7% in whiteness, 1.2-2.2% in L(∗) values, 3.3-3.5% in opacity and 16.1-27% in yellowness). These variations are not in ranges able to cause problems in current paper recycling processes and restrict the use of recycled paper in current applications. Moreover, real impacts on industrial recycling are expected to be even significantly lower since the proportion of paper product with printed circuits in the current paper waste streams are much lower than the ones tested in this work. However, it should be underlined the fact that this situation may change over the next years due to the future developments in printed electronics and the gradual penetration of these types of devices in the market., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In the present study, functionalization of mixed office waste (MOW) paper has been carried out to synthesize carboxymethyl cellulose, a most widely used product for various applications. MOW was pulped and deinked prior to carboxymethylation. The deinked pulp yield was 80.62 ± 2.0% with 72.30 ± 1.50% deinkability factor. The deinked pulp was converted to CMC by alkalization followed by etherification using NaOH and ClCH2COONa respectively, in an alcoholic medium. Maximum degree of substitution (DS) (1.07) of prepared CMC was achieved at 50 °C with 0.094 M and 0.108 M concentrations of NaOH and ClCH2COONa respectively for 3h reaction time. The rheological characteristics of 1-3% aqueous solution of optimized CMC product showed the non-Newtonian pseudoplastic behavior. Fourier transform infra red (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscope (SEM) study were used to characterize the CMC product., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Novel lightweight composite foams based on recycled polypropylene reinforced with cellulosic fibres obtained from agricultural residues were prepared and characterized. These composites, initially prepared by melt-mixing recycled polypropylene with variable fibre concentrations (10-25 wt.%), were foamed by high-pressure CO(2) dissolution, a clean process which avoids the use of chemical blowing agents. With the aim of studying the influence of the fibre characteristics on the resultant foams, two chemical treatments were applied to the barley straw in order to increase the α-cellulose content of the fibres. The chemical composition, morphology and thermal stability of the fibres and composites were analyzed. Results indicate that fibre chemical treatment and later foaming of the composites resulted in foams with characteristic closed-cell microcellular structures, their specific storage modulus significantly increasing due to the higher stiffness of the fibres. The addition of the fibres also resulted in an increase in the glass transition temperature of PP in both the solid composites and more significantly in the foams., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H(2)O(2), enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment.

Co-firing of coal and paper mill sludge was conducted in a 103 MWth circulating fluidized bed boiler to investigate the effect of the sludge feeding rate on emissions of SOx, NOx, and CO. The preliminary results show that emissions of SOx and Nx decrease with increasing sludge feeding rate, but CO shows the reverse tendency due to the decrease in combustion temperature caused by a large amount of moisture in the sludge. All emissions met the local environmental requirements. The combustion ashes could be recycled as feed materials in the cement manufacturing process.