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Grasses have emerged as potential alternative raw materials which can replace wood for pulp and paper products. Various species of grasses have been explored previously for pulp and paper production. This study is aimed to investigate pulp and papermaking characteristics of a grass species namely Cymbopogon winterianus Jowitt which is commonly known as citronella grass. This grass was subjected to proximate chemical characterisation; fibre morphology analysis; soda, soda-AQ (soda-anthraquinone), and kraft pulping; elemental chlorine free bleaching using D0EPD1 (D = ClO2 in acidic medium; EP = alkaline extraction with addition of H2O2; 0 and 1 = initial and final stage) sequence; and evaluation of physical strength properties of paper hand sheets. The pulp and paper hand sheets were also examined through SEM (scanning electron microscope) and FTIR (Fourier-transform infrared) spectroscopy to observe the structural and functional group variations. The proximate chemical analysis of citronella grass was found superior in terms of α-cellulose (38.10%), pentosans (22.30%) and alkali solubility (28.20%) while inferior in terms of ash (8.20%), lignin (25.10%) and alcohol benzene solubility (6.31%) with respect to some other grass species used for pulp and papermaking. Fibre length (0.69–0.74 mm) and fibre width (13.8–15.1 μm) were also comparable to other grass species. Brown pulp characteristics such as screened yield (44.67%), brightness (~24 %ISO) and kappa number (~20) revealed superiority of soda-AQ pulping among all the pulping processes while the kraft pulp exhibited the highest brightness (83.05 %ISO) and intrinsic viscosity (17.6 cP) after D0EPD1 bleaching. Tear index, tensile index and burst index of paper hand sheets obtained from bleaching of soda-AQ and kraft pulps were almost similar but higher to that of bleached soda pulp. The citronella grass was found suitable for producing writing and printing grade paper based on processes and optimised parameters described in this study.

Morphology and anatomy of pulp fibres are very crucial in determining the physical and strength properties of paper sheets prepared from them. This study reports the morphological and anatomical features of bleached soda, soda-AQ (Soda-anthraquinone) and kraft pulp fibres obtained from solid residues left after extraction of essential oil from Citronella grass (Cymbopogon winterianus Jowitt) using hydro-distillation. Their surface morphology and structural properties were also analyzed using SEM (Scanning electron microscope) and FTIR (Fourier transform infrared) spectroscope. The pulps exhibited mean length-weighted length ∼709–736 µm, average fibre width ∼13.5–14.4 µm, average fibre curl 8%, average fines length ∼49–51 µm and average fines area ∼1001–1058 µm. The parenchyma length, parenchyma width, vessels length, vessels width, lumen diameter and cell wall thickness of the bleached soda–AQ pulp were found to be 205.92 µm, 96.62 µm, 515.84 µm, 35.28 µm, 4.45 µm and 4.53 µm respectively. SEM analysis of paper hand sheets revealed a dense network of well bounded fibres within the matrix while FTIR analysis demonstrated presence of characteristic bands of cellulose, lignin and hemicellulose in pulp samples. Comparison of morphological and anatomical features of these pulps with those of other grasses and non-woody raw materials confirmed the suitability of essential oil isolated Citronella grass as potential raw material for pulp and paper industry.

Melia dubia is a recently identified hardwood for papermaking. This study reports oxygen delignification of its kraft pulp. Modeling of O2 delignification was done implementing central composite design taking temperature, time and NaOH charge as process parameters while pulp yield, kappa number, intrinsic viscosity and brightness were the process outputs. The high precision quadratic models developed for O2 delignification revealed antagonistic, synergistic and significant interaction effects between temperature, time and NaOH charge. The optimum values of process parameters estimated were 90 °C, 90 min and 1.39% respectively which gave pulp yield 96.64%, total kappa number 10.52, intrinsic viscosity 628.54 cm3/g and brightness 42.52% which were very much comparable to other papermaking raw materials. On the whole, the optimization desirability obtained for O2 delignification was 0.621. The overall O2 delignification efficiency based on the total kappa number and the true lignin kappa number was found to be 30.33% and 38.23% respectively. The O2 delignification practiced in this investigation led to 10.42% increase in brightness and 19.93% reduction in viscosity which would prove advantageous for subsequent elemental and total chlorine free bleaching.

The present study investigates the feasibility of synthesis of environmentally benign heterogeneous carbonaceous catalyst and biodiesel production from a single source i.e. Mesua ferrea Linn (MFL) seeds. The study primarily focuses on the optimisation of biodiesel synthesis process considering four parameters viz. reaction time, temperature, catalyst loading and methanol to oil ratio (M/O). The parametric influence on the free fatty acid (FFA) conversion has been studied to evaluate the most significant parameters. The contribution factor and analysis of variance results reveal that temperature is the most significant parameter influencing the FFA conversion followed by reaction time and catalyst content. The optimum conditions observed for maximum FFA conversion of 95.57% were: temperature 55 °C, time 2 h, catalyst content 10 wt% and M/O 6:1. The physico-chemical properties of the produced Mesua ferrea oil methyl ester (MFOME) were analysed following ASTM standard methods and found to be within limit; and compatible with the conventional diesel. Thus, the study suggests that the MFL seeds could be a promising source for the synthesis of an effective heterogeneous catalyst; and eco-friendly energy efficient sustainable fuel through the concept of green chemistry by converting waste into valuable commodity towards mitigation of increased energy demand.

Adsorption characteristics of nitrogen onto granular activated carbon for the wide range of temperature (303–323 K) and pressure (0.2027–2.0265 MPa) have been reported for a single bed pressure swing adsorption refrigeration system. The experimental data were fitted to Langmuir, Dubinin-Astakhov and Dubinin-Radushkevich (D-R) isotherms. The Langmuir and D-R isotherm models were found appropriate in correlating experimental adsorption data with an average relative error of ±2.0541% and ±0.6659% respectively. The isosteric heat of adsorption data were estimated as a function of surface coverage of nitrogen and temperature using D-R isotherm. The heat of adsorption was observed to decrease from 12.65 to 6.98 kJ.mol−1 with an increase in surface concentration at 303 K and it followed the same pattern for other temperatures. It was found that an increase in temperature enhances the magnitude of the heat of adsorption.

This investigation is aimed to explore the pulp and papermaking potential of solid residue left after isolation of essential oil from Cymbopogon winterianus Jowitt using hydro distillation, as well as to evaluate the physical strength properties of pulp and paper produced from it. Soda, soda–AQ (soda–anthraquinone) and kraft pulping of oil isolated C. winterianus were optimized and the corresponding optimum unbleached pulp in each process was subjected to environment friendly ECF (elemental chlorine free) bleaching using D1EpD2 (D = chlorine dioxide in acidic medium; Ep = alkaline extraction with addition of hydrogen peroxide; 1 and 2 = first and second time) sequence. Fibre morphological investigation and fibre classification of bleached pulp from every optimized pulping process were also carried out. Hand sheets of bleached pulps were prepared to evaluate the physical strength properties. All the methods were followed as per standard procedures. The proximate chemical composition of oil isolated C. winterianus revealed 62.70% holocellulose, 37.62% alpha-cellulose, 21.10% pentosans and 24.10% lignin. Kraft pulping at 12% NaOH dose and 20% sulphidity produced unbleached pulp with kappa 18.72, yield 43.68%, brightness 21.36% and viscosity 32.6 cp; while bleached pulp with brightness 83.67% and viscosity 16.7 cp. However, hand sheets prepared from soda–AQ pulping exhibited tensile index 31.5 N m/g, tear index 5.02 m Nm2/g and burst index 2.20 kPam2/g which were superior to kraft pulping. Soda pulp demonstrated inferiority in quality to kraft and soda–AQ pulps. No significant differences were observed in fibre morphology of pulps from different processes while fibre classification revealed maximum useful bleached fibres 55.9% from kraft pulping. This research proved that C. winterianus solid residue left after isolation of essential oil could be a substantial source for pulp and papermaking using conventional pulping processes and ECF bleaching sequence at process conditions described in this work.

Graphical abstract, The present investigation highlights the feasibility of a polymer grafting process to enhance the durability and flame retardancy of rice straw towards application as a low cost roofing material. The success of this grafting methodology was perceived to depend upon a bi-step pre-treatment process encompassing delignification and inorganic salts dispersion. Subsequently free radical polymer grafting of acrylonitrile onto rice straw was implemented by immersion mechanism initiated by oxalic acid-potassium permanganate initiator. The percentage of grafting, limiting oxygen index (LOI), biodegradability of the grafted rice straw and grafting yield percentage was estimated to be 57%, 27%, 0.02% and 136.67%, respectively. The weight loss of polymer grafted rice straw implied its less biodegradability over raw straw. Thus, the process of grafting contrived in the present analysis can be a promising and reliable technique for the efficient utilization of rice straw as an inexpensive roofing element through the augmentation of its durability and flame retardancy.

Traditional sandy soil stabilizers such as lime cement, fly ash and bituminous materials, etc., usually require long curing time. Hence now a day, polymer stabilizer is used more extensively because of its stable chemical property and shorter curing time. For the developing organization, it is important to judge the performance of stabilized soil during its developing stages only. This paper aims to highlight a quick and easy test to evaluate the mechanical performance of such polymer based stabilized soil. For this study, three different kinds of polymer stabilizers at developing stage were evaluated against a market ready product. The analysis of the test result include a comparison of the strength, moisture loss rate and strain energy under different curing time, polymer type, polymer additive amount and test conditions. This study shows that the strength of the stabilized sandy soil is significantly increased both under wet and dry conditions by using the polymer additives. With the procedure mentioned in the paper it was easier to identify the relative merits and demerits of each product.

Development of large scale commercial pulping and papermaking processes using agricultural solid residues as raw materials is ecologically and environmentally important. This paper reports pilot scale soda-anthraquinone pulping of palm oil empty fruit bunches and elemental chlorine free bleaching of resulting pulp using DEpD sequence. The physical and morphological properties of resulting bleached and unbleached pulp fibres along with yield have been determined. The pilot scale unbleached pulp exhibited brightness 31.4%, kappa number 18, viscosity 845 mL/g, tensile index 59 Nm/g, burst index 5 kN/g and tear index 7.8 mNm 2 /g with a yield of 48% and bleached pulp resulted in brightness 85%, viscosity 650 mL/g, tensile index 48 Nm/g, burst index 4.70 kN/g and tear index 9.1 mNm 2 /g. Comparison of these values with those obtained at lab scale by various researchers through different processes revealed that the operating conditions adopted in this study can be successfully implemented at a paper mill for commercial production of pulp and paper from palm oil empty fruit bunches.

The physical properties and performance of hot mix asphalt are governed by the properties of the aggregate, properties of the asphalt binder and asphalt–aggregate interactions. The study is aimed to compare the behaviour of bitumen containing various type of modifiers [styrene-butadiene-styrene (SBS) and ethylene-vinyl-acetate (EVA)] and aggregates (acidic and basic characters) for preparing hot mix asphalt on permanent deformation. Rutting and static creep tests were performed on various mixes to evaluate permanent deformation. Dynamic shear rheometer was used to determine the rheological properties and hence rutting parameter (G*/Sinδ). The results indicate that polymer modification increased rutting resistance. Moreover, samples prepared with EVA are more resistant to deformation compared to those prepared with SBS. Mixes consisting of quartzite aggregate are likely to deform more compared to marble mixes, both for modified and unmodified bituminous mixes, but the recovery of quartzite mixes on removal...

Soil applicable biochar has been prepared from bark of Leucaena leucocephala wood which is a waste generated during its pulping and papermaking process. The slow pyrolysis process adopted for this purpose has been modelled and optimized employing central composite design and desirability function under response surface methodology taking temperature (308–592 °C) and time (35–205 min) as independent variable while yield, loss on ignition, stable organic matter, oxidisable carbon and carbon liability index as dependent variable. L. leucocephala bark was characterized in terms of proximate analysis (moisture 4.90%, ash 7.20%, fixed carbon 18.10%, volatile matter 69.80%), elemental analysis (carbon 45.78%, hydrogen 10.67%, nitrogen 1.77%, oxygen 32.08%, sulphur 0.09%), lignocellulosic composition (holocellulose 45.86%, hemicellulose 15.01%, lignin 34.75%) and compared with a wide range of feedstocks to find its suitability towards biochar production. The optimum pyrolysis temperature and residence time were found to be 350 °C and 60 min respectively which gave biochar yield 53.16%, loss on ignition 88.17%, oxidisable carbon 28.82%, stable organic matter 38.48%, and carbon liability index 0.32. The biochar produced at optimum conditions were characterized by proximate analysis (moisture 0.65%, ash 11.83%, fixed carbon 40.2%, volatile matter 47.57%) and elemental analysis (carbon 62.91%, hydrogen 3.12%, nitrogen 2.65%, oxygen 20.74%, sulphur 0.05%). The O/C ratio of 0.25 and H/C ratio of 0.60 confirmed its life between 100–1000 years and appropriateness for soil application as well as carbon sequestration.

Pressure swing adsorption of nitrogen onto granular activated carbon in the single-bed adsorber–desorber chamber has been studied at six different pressures 6–18 kgf/cm2 to evaluate their performance as an alternative refrigeration technique. Refrigerating effect showed a linear rise with an increase in the operating pressure. However, the heat of adsorption and COP exhibited initial rise with the increasing operating pressure but decreased later after reaching a maximum value. The COP initially increases with operating pressures however, with the further rise of operating pressure it steadily decreased. The highest average refrigeration, maximum heat of adsorption and optimum coefficient of performance was evaluated to be 415.38 W at 18 kgf/cm2, 92756.35 J at 15 kgf/cm2 and 1.32 at 12 kgf/cm2, respectively. The system successfully produced chilled water at 1.7 °C from ambient water at 28.2 °C.

Experimental and statistical investigations on the removal of chromium (VI) from simulated wastewater over the influence of different parameters viz. pH, cross flow rate, and transmembrane pressure were carried out in cross-flow nanofiltration through central composite response surface design. A satisfactory prediction second order regression model was developed and analysis of variance (ANOVA) showed a high coefficient of determination with R2 value of 0.9820. The maximum chromium (VI) rejection of 0.9893 and permeate flux of 38 L/h were achieved at optimum parametric conditions of pH 11, cross flow rate 700 L/h and transmembrane pressure 10 bar. The results indicate that the chromium (VI) rejection strongly depends not only on linear and square effects of pH, cross flow rate, and transmembrane pressure but also on interaction effects of pH and transmembrane pressure as well as cross flow rate and transmembrane pressure. The study reveals that the nanofiltration process at the optimal conditions could lead to a significant result in removal of chromium (VI) from wastewater. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1332–1340, 2015

A three-layered feed-forward artificial neural network (ANN) model has been designed to predict the adsorption efficiency and adsorption capacity for the adsorptive removal of chromium (VI) from synthetic wastewater. The adsorbent dose, wastewater pH, initial pollutant concentration and contact time were used to develop the network. The data used to train and test the model were obtained from several batch experiments. Various algorithms and transfer functions for hidden layer were tested to find the most reliable network. Broyden–Fletcher–Goldfarb–Shanno (BFGS) quasi-Newton backpropagation algorithm gave the most satisfactory results for adsorption efficiency. Resilient and BFGS quasi-Newton backpropagation were the most suitable algorithm for adsorption capacity. The best combination of training algorithm and transfer function for adsorption efficiency was found to be trainrp and poslin, while poslin produced simulated results within 10% deviation for adsorption capacity. Eight to eleven neurons...

This paper investigates the adsorptive removal of Cr (VI) from aqueous solution over commercial powdered activated carbon (PAC) and carries optimisation of removal efficiency for the process using response surface methodology (RSM). The effects of different parameters such as pH, initial Cr (VI) concentration, adsorbent dose, contact time and temperature on adsorption were studied to find the best operating conditions. This study showed that when initial concentration was 50 ppm, 100% Cr (VI) removal was possible with pH 2 and 2 g L−1 PAC concentration. Different adsorption kinetic models and isotherms were compared respectively with the proposed kinetic model based on liquid phase adsorbate concentration and the developed new three-parameter isotherm. The new isotherm supported the experimental results with a better accuracy. The main process parameters considered for optimisation were pH, adsorbent dose and adsorption time. The experimental was designed according to central composite rotatable design (CCRD) and second order regression model was developed for regression analysis and ANOVA study. The optimum pH, PAC dose and time were found to be 2.32, 1.79 g L−1 and 25.76 min. Pareto analysis established that PAC dose was the most influential parameter.

Replacement of halogenated refrigerants with a suitable refrigeration system in order to prevent ozone layer depletion and minimize global warming has been a matter of research and worldwide attention for some decades. This paper presents the design and description of a single chambered experimental model for cold generation based on pressure swing adsorption mechanism with an objective to propose a feasible refrigeration system to replace halogenated refrigerants. Granular activated carbon (ACG-825-1.5) manufactured indigenously from matured coconut shell and carbon dioxide has been used as representative adsorbent–adsorbate pair. Refrigerating effect and coefficient of performance for the system have been investigated and were found to be 120.61 J/s and 3.014 respectively. The model successfully produced chilled water at 4 °C (277 K) from ambient water available at 26 °C (299 K). Details of the experimental results and adsorption–desorption isotherm for the system has been described. This work also highlights a novel method of capturing carbon dioxide by utilizing it as an adsorbate in such a refrigeration system.

Adsorption over TiO2 is used efficiently for reactive dyes removal from wastewater. This paper investigates adsorption efficiency for Reactive Red 198 (RR198) removal over TiO2 adsorbent using response surface methodology. The main process parameters considered for optimisation were pH, adsorbent dose, and adsorption time. The experimental scheme was designed according to central composite rotatable design and second order regression model was developed. For regression analysis and ANOVA study, software MINITAB 15 was used. The optimum pH, TiO2 dose, and time were found to be 4.3, 4.3 g L−1, and 32.42 min, respectively. Complete removal was observed. Pareto analysis established pH the most influential parameter. L'adsorption sur TiO2 est utilisee efficacement pour l'elimination des colorants reactifs des eaux usees. Cet article examine l'efficacite de l'adsorption pour l'elimination du rouge reactif 198 (RR198) sur un adsorbant au TiO2 en utilizant la methodologie de surface de reponse. Les parametres principaux du processus consideres pour l'optimization etaient le pH, la dose d'adsorbant et le temps d'adsorption. Le projet experimental a ete concu selon un concept rotatif composite central et un modele de regression de second ordre a ete developpe. Pour l'analyse de regression et l'etude ANOVA, le logiciel MINITAB 15 a ete utilise. Le pH optimum, la dose de TiO2, et le temps etaient de 4.3, 4.3 g L−1, et 32.42 min, respectivement. On a observe une elimination complete. Une analyse de Pareto a etabli que le pH etait le parametre le plus influent.