The current research mainly focuses on transforming low-quality waste into value-added nanomaterials and investigating various ways of utilising them. The hydrothermal preparation of highly fluorescent N-doped carbon dots (N–CDs) was obtained from the carboxymethylcellulose (CMC) of oil palm empty fruit bunches and linear-structured polyethyleneimines (LPEI). Transmission electron microscopy (TEM) analysis showed that the obtained N–CDs had an average size of 3.4 nm. The N–CDs were monodispersed in aqueous solution and were strongly fluorescent under the irradiation of ultra-violet light. A detailed description of the morphology and shape was established using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was shown that LPEI were successfully tuned the fluorescence (PL) properties of CDs in both the intrinsic and surface electronic structures, and enhanced the quantum yield (QY) up to 44%. The obtained N–CDs exhibited remarkable PL stability, long lifetime and pH-dependence behaviour, with the excitation/emission maxima of 350/465.5 nm. Impressively, PL enhancement and blue-shifted emission could be seen with the dilution of the original N–CDs solution. The obtained N–CDs were further applied as fluorescent probe for the identification of Cu2+ in aqueous media. The mechanism could be attributed to the particularly high thermodynamic affinity of Cu2+ for the N-chelate groups over the surface of N–CDs and the fast metal-to-ligand binding kinetics. The linear relationship between the relative quenching rate and the concentration of Cu2+ were applied between 1–30 µM, with a detection limit of 0.93 µM. The fluorescent probe was successfully applied for the detection of Cu2+ in real water. Moreover, a solid-state film of N–CDs was prepared in the presence of poly (vinyl alcohol) (PVA) polymer and found to be stable even after 72-h of continuous irradiation to UV-lamp. In contrast to the aqueous N–CDs, the composite film showed only an excitation independent property, with enhanced PL QY of around 47%. Due to the strong and stable emission nature of N–CDs in both aqueous and solid conditions, the obtained N–CDs are ideal for reducing the overall preparation costs and applying them for various biological and environmental applications in the future.

A versatile synthetic approach for development of highly fluorescent nitrogen-doped carbon dots (n-cDs) from carboxymethylcellulose in the presence of linear polyethyleneimine (Lpei) has been developed. According to single factor method, central composite design incorporated with response surface methodology matrix was applied to find and model optimal conditions for the temperature (220-260 °C), duration (1-3 h) and LPEI weight (0.5-1.5%). The statistical results show that duration was the most significant parameter for efficient carbonization conversion rate in comparison with temperature and Lpei weight. the reduced cubic model (R 2 = 0.9993) shows a good correlation between the experimental data and predicted values. the optimal variables were temperature of 260 °C, duration of 2 h and LPEI weight of 1%. Under these conditions, quantum yield of up to 44% was obtained. The numerically optimized N-CDs have an average size of 3.4 nm with graphitic nature owing to the abundant amino species incorporated into the carbon core framework. the blue-green n-cDs possess emission dependent upon the solvent polarity, wide pH stability with enhanced emission in an acidic environment. Impressively, the N-CDs show long-shelf-life for up to 1 year with no noticeable precipitation. the n-cDs were able to recognize a high concentration of fe 3+ ions with a detection limit of 0.14 μM in acidic solution owing to the special coordination for Fe 3+ to be captured by electron-donating oxygen/ amino groups around n-cDs. Moreover, the n-cDs can also be used as a new kind of fluorescent ink for imaging applications. Carbon dots (CDs) are the latest member of fluorescent carbon nano-sized family. Typically, CDs are nearly spherical-shaped nanoclusters with sizes of less than 10 nm and consist of amorphous or crystalline cores with sp 2 carbon atoms 1. Since the first established work 2 , CDs have attracted a considerable focusing in the fields of wastewater treatment, photocatalysis, bioimaging, cancer therapy and chemical sensing 3,4. This is owing to their feature of having outstanding optical properties, including excellent biocompatibility, tuneable photoluminescence, negligible toxicity, ease of production and resistance to photobleaching in comparison to QDs counterparts 5-7. It is well known that QDs, for instance, tend to be decayed in the biological environment leading to a serious toxicity concern 8 .

This research demonstrates an economical and efficient reduction of carbon foot print. Tapioca powder as a source of organic carbon was utilized in the synthesis of carbon dots through optimization of the synthesis parameters such as temperature, dosage and time. Photoluminescent quantum yield (PLQY) was obtained under the visible region of 340 nm at 34.9%, which was achieved without dopants such as sulfur and nitrogen that are popularly used to increase the value of photoluminescence. The characterization of carbon dots such as FTIR and HrTem, were carried out for the analysis of functional groups, particle sizes (1‐5 nm) and shapes (quasi‐spherical). The high carbon‐carbon bonds and oxygen groups detected in FTIR analysis validates the basis of fluorescence of carbon dots and also presence of hydroxyl (OH), carboxylic acids (COO), and other vital functional groups (C=O, C−O‐C, C−H). These characteristics makes tapioca based carbon dots suitable for application in the fields of environmental studies including sensitive detection and absorbance of pollutants in water and bio imaging in health sciences.

Bio based nitrogen doped carbon dots (N-CDs) were obtained from empty fruit bunch carboxymethylcellulose and ethylenediamine (EDA) through one-pot hydrothermal carbonization route. The optimum as-formed N-CDs were thoroughly characterized via Transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared (FTIR), X-ray photoelectron spectra (XPS), UV-vis spectra (UV-Vis) and Fluorescence spectra (PL). Response surface methodology was statistically used to assess three independent variables that have major influence on the fluorescence quantum yield (QY), including temperature (230-270 °C), time (2-6 h) and EDA mass (10%-23.3%). Based on analysis of variance (ANOVA) results, synthesis temperature was found to be the most influential factor on the QY, followed by time and EDA mass. Higher temperature, long synthesis time and high amount of EDA were satisfactorily enough for efficient carbonization conversion rate and obtaining highest QY of N-CDs. The obtained quadratic model (R2 = 0.9991) shows a good correlation between the experimental data and predicted values. The optimum synthetic parameters are of 270 °C temperature, 6 h reaction time and 23.3% of EDA mass. The optimized as-made N-CDs exhibited blue photoluminescence with both excitation dependent/independent phenomena and high nitrogen content. The maximum emission intensity was 426 nm at a maximum excitation wavelength of 320 nm, with a QY of up to 22.9%. XPS and FTIR data confirmed the existence of polar containing groups, such as carbonyl, carboxyl, hydroxyl and amino groups over the surface of N-CDs whereas nitrogen species in the form of (pyridinic and graphitic − N) were introduced in the aromatic carbon domains, which imparts the hydrophilic and photostability of N-CDs. Taking into account the lowcost and sustainable production of N-CDs, this method considered a feasible route for converting low quality waste into value-added nanomaterials and utilizing for different functionalization processes and analytical applications.

Low value waste resources have been converted into value-added luminescence carbon dots for copper adsorption from contaminated water.

Despite the advantages of continuous fermentation whereby ethanol is selectively removed from the fermenting broth to reduce the end-product inhibition, this process can concentrate minor secondary products to the point where they become toxic to the yeast. This study aims to develop a new mathematical model do describe the inhibitory effect of byproducts on alcoholic fermentation including glycerol, lactic acid, acetic acid, and succinic acid, which were reported as major byproducts during batch alcoholic fermentation. The accumulation of these byproducts during the different stages of batch fermentation has been quantified. The yields of total byproducts, glycerol, acetic acid, and succinic acid per gram of glucose were 0.0442, 0.023, 0.0155, and 0.0054, respectively. It was found that the concentration of these byproducts linearly increases with the increase in glucose concentration in the range of 25−250 g/L. The results have also showed that byproduct concentration has a significant inhibitory effect on specific growth coefficient (μ) whereas no effect was observed on the half-velocity constant (K s ). A new mathematical model of alcoholic fermentation was developed considering the byproduct inhibitory effect, which showed a good performance and more accuracy compared to the classical Monod model.

As a remedy for environmental pollution, a versatile synthetic approach has been developed to prepare polyvinyl alcohol (PVA)/nitrogen-doped carbon dots (CDs) composite film (PVA-CDs) for removal of toxic cadmium ions. The CDs were first synthesized using carboxymethylcellulose (CMC) of oil palms empty fruit bunch wastes with the addition of polyethyleneimine (PEI) and then the CDs were embedded with PVA. The PVA-CDs film possess synergistic functionalities through increasing the content of hydrogen bonds for chemisorption compared to the pure CDs. Optical analysis of PVA-CDs film was performed by ultraviolet-visible and fluorescence spectroscopy. Compared to the pure CDs, the solid-state PVA-CDs displayed a bright blue color with a quantum yield (QY) of 47%; they possess excitation-independent emission and a higher Cd2+ removal efficiency of 91.1%. The equilibrium state was achieved within 10 min. It was found that adsorption data fit well with the pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption uptake was 113.6 mg g−1 at an optimal pH of 7. Desorption experiments showhe that adsorbent can be reused fruitfully for five adsorption-desorption cycles using 0.1 HCl elution. The film was successfully applied to real water samples with a removal efficiency of 95.34% and 90.9% for tap and drinking water, respectively. The fabricated membrane is biodegradable and its preparation follows an ecofriendly green route.

Aims:A pilot study was done to evaluate the physical and mechanical properties of the Iraqi plaster (Al-Ahliya gypsum) and Plaster of Paris (British Gypsum), and to improve the quality by the incorporation of some additives. Materials and Methods: Two types of gypsum products were used in this study (Iraqi plaster, Plaster of Paris). Three types of additives {gum arabic at a concentration of (0.1%, 0.25%, 0.35%, 0.50%), calcium oxide at a concentration of (0.1%, 0.25%, 0.35%, 0.50%, 0.75%), and ferric oxide acts as a pigment (blue or red) at a concentration of (0.1%, 0.2%)} were incorporated after preparation into the weighted dried gypsum powder. The effects of these additives on the physical and mechanical properties of the experimental gypsum products (Iraqi plaster and Plaster of Paris) have been evaluated by measuring the water/powder ratio, setting time, linear setting expansion, and compressive strength. Four hundred sixty gypsum samples were prepared for this study. Mean, standard deviation, variance (ANOVA), and Duncan's multiple range tests were used to analyze the measurements. Results: ANOVA showed that there was a significant difference in the water/ powder ratio, setting time, linear setting expansion, and compressive strength between Iraqi plaster and Plaster of Paris depending upon the type and the concentration of each additive used. Conclusions: The last concentration of each additive (gum arabic 0.5%, calcium oxide 0.75%, or ferric oxide 0.2%) in all the experimental measurements that are incorporated within the two gypsum products showed results within the acceptable range of American Dental Association (ADA) specification No. 25.