Sintered bottom ash (SBA) and vitrified ash (VA) derived from the incineration of municipal solid waste (MSW) at 1200 °C were used in this study as replacements for Type 2 Portland cement (CEM-II) based mortars. This approach negates the need to send them to landfill, benefits the circular economy and contributes towards the decarbonisation of cementitious construction materials in response to international net zero carbon emission agendas. The material (physico-chemical) characteristics of VA and SBA were analysed before being used as partial replacements for CEM-II in mortars, whereby compressive strength (CS) was the primary criterion for assessing engineering performance. VA and SBA replaced CEM-II at dosages of 10%, 25% and 50% based on their high inorganic and pozzolanic contents; whereby the 10% and 25% replacements did not compromise mortar strength. The alkalinity and pozzolanic properties of SBA collectively indicated it has greater potential as a cementitious material over VA, which possessed a neutral pH. The 28-day CS recorded for mixtures containing 25% VA and 10% SBA were 13.74 MPa and 11.77 MPa, respectively compared with 17.06 MPa for CEM-II control samples. The use of 2% additional water in 25% SBA mortar designs improved strength further, indicating that SBA’s water retention properties permitted further hydration and strength development with curing. Microstructural, mineralogical and infrared spectroscopy analyses indicated that these strengths were owed to the formation of silicate-based hydration products. The outcomes from this study highlight that SBA has potential for replacing CEM-II and VA as a filler in cementitious mortar. Graphical Abstract

Deep dry soil mixing is a ground improvement technique commonly used for treating soft soils. Portland cement is the most commonly used binder, but its long-term use is unsustainable due to the high CO2 emissions associated with its manufacture. Alkali-activated cements are a low-carbon alternative that involve the use of pozzolanic industrial by-products and wastes. This study provides insights into the one-dimensional compressibility, internal cemented structure and leaching characteristics of an alluvial soil stabilized with a new 100% waste-based cementitious binder, comprising biochar as the alkali activator and blast furnace slag as the pozzolan. The binder recently was demonstrated by the authors to satisfy European soil stabilization 28-day compressive strength requirements when using dosages of 7.5% and 10% by dry weight. The biochar successfully activated the pozzolanic properties of the slag, whereby the stabilized soil mixtures developed a cemented microstructure which resulted in improvements in compressibility and stiffness. Oedometer data sets for untreated and biochar-slag- and CEM-II-stabilized alluvium were processed successfully through a framework developed by the authors to quantify their artificially cemented internal structure, for use as an input parameter in advanced constitutive soil models. Leaching results indicated that the heavy and trace metal content of 1- and 28-day cured biochar-slag-stabilized samples complied with UK and European waste acceptance criteria, and with mean baseline heavy metal concentrations for groundwater resources in England and Wales. This study advocates the new biochar-slag binder as a suitable replacement for portland cements in soil stabilization, contributing to the path toward net zero carbon emissions for the ground engineering sector and improving the circular economy.

Pyrolysis provides a sustainable solution for managing post-consumer mixed plastic waste (PC-MPW) streams by producing valuable mixtures of liquids and gases, which have potential for use as fuels. Compared with landfilling, gasification and incineration processes, pyrolysis has the smallest environmental footprint. Waxes produced as an intermediate product of controlled pyrolysis conditions have been used as viscosity-reducing additives in modified asphalts, which reduce energy requirements for heating and mixing on site. The chars produced from PC-MPW pyrolysis have been used to produce activated carbon (adsorbents), additives in epoxy resins and fuel briquettes. These chars have proven to increase the conductivity, thermal stability and non-flammability of epoxy resin composites. Furthermore, the chars also have potential as additives in concretes to reduce the carbon footprint associated with Portland cement production. Albeit PC-MPW-chars have not been used in civil engineering applications to date, chars derived from other organic sources (e.g. wood) have been successfully used in cement admixtures and demonstrated their atmospheric carbon sequestration and strength gaining capabilities. The material properties of the chars that are responsible for producing such promising performances include high porosity (which enables water absorption and retention capacities), high surface area and reactivity (particularly for chars produced at higher pyrolysis temperatures) for promoting the formation of cementitious gels. Furthermore, pulverised chars act as a “micro-filler” within cementitious materials, whereby they fill pore spaces and increase material strength and stiffness. This study highlights the promise of PC-MPW chars as a low carbon additive for use in cement-based construction materials.

Portland cement forms the basis of most binders used in deep dry soil mixing, significantly improving the shear strength and compressibility properties of soils. However, due to the high environmental and socio-economic impacts of cement production, there is great interest in developing alternative low-carbon binders for soil stabilisation. One of the most desirable routes involves the use of industrial by-products, such as ground granulated blast furnace slag, whose pozzolanic properties require activation by alkali agents. This paper assesses the feasibility of using sewage treatment sludge biochar as a low-carbon 100% waste-based alternative to traditional alkali agents. Two biochar:slag ratios (0.5:0.5 and 0.67:0.33) were added to an artificial soil at dosages of 7.5 and 10% by dry weight and cured for up to 56 days. The engineering performance of these stabilised soil mixtures was assessed by performing a suite of compressive strength, pH, water content, mineralogical and microstructural analyses. Results were compared with those of untreated and CEM-II stabilised alluvium, along with data published in the literature. Biochar was observed to successfully activate the pozzolanic properties of the slag, whereby the studied mixtures resulted in 28-day strengths that met European soil stabilisation standards requirements. Binder mixtures with higher biochar concentrations achieved greater strengths. The best performing mixture had a biochar-slag ratio of 0.67:0.33 and dosage of 10%, which produced strengths up to 1243 kPa. This study suggests that the biochar-slag binder has encouraging prospects for replacing Portland cements in soil stabilisation, reducing the carbon footprint of the construction sector and improving the circular economy.

Soil fertilization with trace-metal rich organic fertilizers such as Fucus serratus seaweed may be an effective way to combat micronutrient deficiency. In this study the kinetics of zinc release from Fucus serratus seaweed was investigated in a packed soil column leaching experiment over 1,776 h. The release of zinc from control (soil only) and treatment (soil + seaweed; equivalent zinc application rate of 1.42 kg ha(-1)) columns, measured by ICP-MS, demonstrated two distinct release stages. The cumulative zinc release data for each phase were fitted to five kinetic models: zero order, first order, Elovich, power function and parabolic diffusion. In the first stage (0-400 hours) the release of zinc from both control and treatment was best described by a parabolic rate law, indicating release of zinc from a soluble soil reservoir. In the second stage (400-1,776 h) zinc release followed a zero order rate law indicative of slow release from an essentially insoluble reservoir. The modelled difference between the amount of zinc released from treatment and control columns in stage 1 (230 +/- 11 mu g) represented the total amount of zinc added via seaweed. The parabolic rate constant for seaweed zinc release was 12.09 mu g g(-1) h(-0.5). In summary, the addition of F. serratus to soil is a viable source of labile zinc and a low cost agronomic option for mitigating zinc deficiency in soils.

Materials with nonlinear optical (NLO) properties have significant applications in different fields, including nuclear science, biophysics, medicine, chemical dynamics, solid physics, materials science and surface interface applications. Quinoline and carbazole, owing to their electron-deficient and electron-rich character respectively, play a role in charge transfer applications in optoelectronics. Therefore, an attempt has been made herein to explore quinoline-carbazole based novel materials with highly nonlinear optical properties. Structural tailoring has been made at the donor and acceptor units of two recently synthesized quinoline-carbazole molecules (Q1,Q2) and acceptor-donor-pi-acceptor (A-D-pi-A) and donor-acceptor-donor-pi-acceptor (D-A-D-pi-A) type novel moleculesQ1D1-Q1D3andQ2D2-Q2D3have been quantum chemically designed, respectively. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) computations are performed to process the impact of acceptor and donor units on photophysical, electronic and NLO properties of selected molecules. The lambda(max)values (321 and 319 nm) forQ1andQ2in DSMO were in good agreement with the experimental values (326 and 323 nm). The largest shift in absorption maximum is displayed byQ1D2(436 nm). The designed compounds (Q1D3-Q2D3) express absorption spectra with an increased border and with a reduced band gap compared to the parent compounds (Q1andQ2). Natural bond orbital (NBO) investigations showed that the extended hyper conjugation and strong intramolecular interaction play significant roles in stabilising these systems. All molecules expressed significant NLO responses. A large value of beta(tot)was elevated inQ1D2(23 885.90 a.u.). This theoretical framework reveals the NLO response properties of novel quinoline-carbazole derivatives that can be significant for their use in advanced applications.

Hydrothermal carbonization (HTC) of microalgae biomass for the production of triacylglycerides is a potentially valuable enabling technology for a waste water treatment-based integrated biorefinery. Here, HTC was used to treat Phaeodactylum tricornutum lipid-rich biomass producing a solid hydrochar from the surface of which adsorbed lipids were removed by hexane extraction following filtration of the solid hydrochar from the process liquid product. Approximately 7% of the input biomass was recovered and transesterified for qualitative and quantitative GCMS analysis for fatty acid methyl esters. Transesterifiable lipids accounted for 94% of the material recovered by solvent extraction. Of the transesterified fatty acids (FA) analysed, the majority was monounsaturated (40.4%) and saturated (37%) C-16 FA. Other FA detected included saturated and monounsaturated C-18 (7.7% and 1.9%) and saturated C-14 (5.3%) and C-25 (1.5%). Thermal analysis (TGA/DSC) of the hydrochar in air showed calorific values of 10.6 MJ kg-1 (delipidated hydrochar) and 3.1 MJ kg-1 (non-delipidated hydrochar) with the latter exhibiting the presence of volatalisable components. Germination trials were conducted to assess the potential phytotoxic effects of these hydrochars. Delipidated hydrochar showed a germination index of 73% suggesting the presence of some phytotoxicity. Non-delipidated hydrochar showed high germination index results of 102% (unground) and 126 % (ground). Taken together with the observation of reduced root hair proliferation in these two test conditions, this suggests the operation of a second phytotoxic effect that is removed by delipidation.

Understanding the physiological properties of populations in response to environmental perturbations remains central to effective implementation of different environmental biotechnologies, including those that are biochar driven. Despite their accepted limitations, accessible molecular microbial ecology profiling techniques continue to have relevance including in emerging research areas such as biochar application. In particular, denaturing gradient gel electrophoresis is one of the most popular tools that have been used to elucidate changes in the structure, diversity, richness, and evenness of microbial communities in different ecosystems. Therefore this chapter provides an illustration and case study of how complementary culture-based and ecogenomic analyses can be applied for the fundamental study of biochar-augmented soils.

The terms biosurfactant and bioemulsifier have often been used interchangeably to describe surface active biomolecules. However, it is important to note that there are marked differences between them especially based on their physico-chemical properties and physiological roles. Although bioemulsifiers and biosurfactants are both amphiphilic in nature and are produced by a wide range of microorganisms, each exhibit characteristic roles in nature. These microbial surfactants have recently received increased scientific attention due to their unique characteristics relative to chemically derived surfactants. Their unique features include; non-toxicity, biodegradability, biocompatibility, efficiency at low concentrations and their synthesis from natural substrates under mild environmental conditions.

The terms biosurfactant and bioemulsifier have often been used interchangeably to describe surface active biomolecules. However, it is important to note that there are marked differences between them especially based on their physico-chemical properties and physiological roles. Although bioemulsifiers and biosurfactants are both amphiphilic in nature and are produced by a wide range of microorganisms, each exhibit characteristic roles in nature. These microbial surfactants have recently received increased scientific attention due to their unique characteristics relative to chemically derived surfactants. Their unique features include; non-toxicity, biodegradability, biocompatibility, efficiency at low concentrations and their synthesis from natural substrates under mild environmental conditions.

Pathogenicity of biosurfactant-producing microorganisms is currently raising some health, safety and environmental concerns. As a result, the industrial-scale production and application of biosurfactants as potential alternatives to the synthetic one is still an unachieved task. The production of biosurfactants using nonpathogenic/recombinant strains requires more attention and investigation for some advantages that includes the discovery of non-toxic biosurfactants suitable for all industrial applications, identifying new biosurfactant congeners with better inherent surface-active properties compared to that from pathogens and synthetic ones and the synthesis of biosurfactant without complex metabolic regulations. Although a number of nonpathogenic/recombinant, eco-friendly biosurfactant-producing strains have been documented, there is need for more research in this area focusing especially on improved biosurfactant production by these strains using optimisation processes and the discovery of new nonpathogenic/recombinant strains using molecular techniques for future sustainability.

Willow, a leading bioenergy feedstock, may be planted for bioremediation and has been used, more recently, as the biomass feedstock in the manufacture of biochar for agricultural applications. Here, we present a detailed study of the physical and chemical factors affecting willow char properties, where the feedstock is a by-product of bioremediation, potentially transferring pollutants such as heavy metals to the wood feed. Biochar samples were produced via pyrolysis of short-rotation coppice willow, grown on contaminated land, using several treatment times at heat treatment temperatures (HTTs) in the range 350–650 °C, under a constant flow of argon, set at either 100 or 500 mL min −1 . The samples were analysed for yield, elemental analysis and structural characteristics, including surface area and pore size distribution, surface functionality and metal content. All chars obtained have high fixed carbon contents but vary in surface characteristics with a marked increase in basic character with increasing HTT, ascribed to the removal of surface oxygen moieties. Results indicate a minimum pyrolysis temperature of 450 °C is required to produce a defined mesoporous structure, as required to facilitate oxygen transport, HTT ≥ 550 °C produces total surface area of >170 m 2 g −1 and, more importantly, an appreciable external surface area suitable for microbial colonisation. The data show that selection and optimisation of char properties is possible; however, the interplay of factors may mean some compromise is required.

Polymethylmethacrylate/cellulose nanocomposites were prepared by in situ polymerization and ex situ dispersion techniques with 10 wt% loading of cellulose nanoparticles. Cellulose nanoparticles were prepared from jute fibers by acid hydrolysis. The suspension polymerization of methylmethacrylate was carried out in presence of cellulose nanoparticles, which were dispersed in water medium and in situ polymethylmethacrylate/cellulose nanocomposite granules were formed. These granules were dissolved in chloroform, sonicated and films were prepared by solution casting method (IPC). Polymethylmethacrylate granules were prepared by similar suspension polymerization process and made into films by solution casting method. Another set of polymethylmethacrylate/cellulose nanocomposite films were prepared by dispersing nanocellulose powder (10 wt%) in polymethylmethacrylate solution and casting into films (EPC). The unreinforced polymethylmethacrylate and polymethylmethacrylate extracted from IPC films were subjected to size exclusion chromatography and nuclear magnetic resonance study. The average molecular weights of neat polymethylmethacrylate and polymethylmethacrylate from IPC were quite close, but the ‘dispersity’ was slightly higher in IPC than that in neat polymethylmethacrylate. Fourier transform infrared spectroscopy revealed some shifts in EPC. X-ray diffraction study showed a similar nature of X-ray diffraction curves in all the samples. Transmission electron microscopy of IPC and EPC showed a better dispersion of fillers and formation of a network structure in IPC, whereas in EPC, the fillers were agglomerated. Surface morphology of the films was examined by field emission scanning electron microscopy and atomic force microscopy. IPC exhibited a much smoother surface compared to that of EPC indicating a more homogeneous dispersion of fillers. IPC showed a higher modulus of elasticity compared to PMMA and EPC. Differential scanning calorimetry showed a shift of glass transition temperature to a higher one (125°C) in IPC compared to that of polymethylmethacrylate (118°C). Thermogravimetric analysis was done to study the thermal degradation behavior of the composites.

Biochar-charcoal used to amend land and sequester carbon-is attracting considerable interest. Its distinctive physical/chemical/biological properties, including high water-holding capacity, large surface area, cation exchange capacity, elemental composition, and pore size/volume/distribution, effect its recognized impacts, especially on microbial communities. These are explored in the context of agriculture, composting, and land remediation/restoration. Considerable focus is given to mycorrhizal associations, which are central to exploitation in environmental technologies involving biochar. The characteristics of biochar, its availability for nutrient cycling, including the beneficial and potentially negative/inhibitory impacts, and the requisite multidisciplinary analysis (physicochemical, microbiological, and molecular) to study these in detail, are explored.

Cellulose nanoparticles (CNPs) were prepared from jute fiber by acid hydrolysis followed by high-speed homogenization. The CNPs were used as fillers in the production of polymethylmethacrylate (PMMA) nanocomposites by in situ suspension polymerization technique. The suspension polymerization of MMA was carried out in the presence of CNPs, which were dispersed in water medium and in situ PMMA/cellulose nanocomposite granules were formed. PMMA polymer, without any filler, was also prepared by similar suspension polymerization technique. PMMA and PMMA/cellulose nanocomposite films were prepared by solution casting method. Viscosity average molecular weights of neat PMMA and the PMMA extracted from PMMA/cellulose nanocomposite granules were determined by viscometric method and average molecular mass of PMMA extracted from PMMA/cellulose nanocomposites was found to be reduced than that of neat PMMA. Attenuated total reflectance Fourier transform infrared spectroscopy was performed to find out any chemical interaction between polymer matrix and the CNPs. X-ray diffraction study and differential scanning calorimetry were done to investigate the structures of the nanocomposite films and the glass transition temperature was found to be lower in the nanocomposite than that in the virgin polymer. Field emission scanning electron microscopy and atomic force microscopy were done to examine the morphology of the films. Such an in situ suspension polymerization technique for the preparation of PMMA/cellulose nanocomposites can be very useful to prepare tailor-made materials. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012