Covid-19 waste facemask conundrum: A facile way of utilization through fabricating composite material with unsaturated polyester resin and evaluation of its mechanical properties

Since the outbreak of novel coronavirus (COVID-19), the use of personal protective equipment (PPE) has increased profusely. Among all the PPEs, face masks are the most picked ones by the mass people for protective purpose. This spawned extensive daily use of face masks and production of masks had to augment to keep up this booming demand. Such extensive use of face masks has resulted in a huge waste generation. Lack of proper disposal, waste management and waste recycling have already led this waste to pervade in the environment. In quest of finding a solution, here in this research, a composite material was fabricated utilizing waste face mask (WFM) with unsaturated polyester resin (UPR) and the mechanical properties were evaluated. The composites were fabricated by incorporating 1%, 2%, 3%, 4% and 5% WFM (by weight) within the UPR matrix in the shredded form following hand lay-up technique. Tensile properties, i.e., tensile strength (TS), tensile modulus (TM) and percentage elongation at break (% EB) as well as flexural properties, i.e., bending strength (BS) and bending modulus (BM) were evaluated for the fabricated composites. According to the results obtained, the 2% WFM loaded composites showed highest values of TS, TM, BS and BM which are 31.61 N/mm2, 1551.41 N/mm2, 66.53 N/mm2 and 4632.71 N/mm2 respectively. These values of 2% WFM loaded composite are 69.58%, 107.78%, 129.49% and 152% higher than the values of the control sample (UPR). Such results depict the successfulness of WFM's incorporation as a reinforcing material in the composite materials. Attenuated Total Reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), water uptake and thickness swelling tests were also carried out for the fabricated composites. FTIR of the collected WFM revealed the fiber to be of polypropylene and the existing functional groups were also identified. The SEM images confirmed the proper adhesion of WFM and UPR in terms of mechanical bonding rather than chemical bonding. Water absorption and dimension change was investigated by water uptake and thickness swelling test. To sum up, the way we have utilized WFM as a reinforcing agent in a composite material, this could be a possible solution for the face mask's waste conundrum

Facile preparation of micro-porous biochar from Bangladeshi sprouted agricultural waste (corncob) via in-house built heating chamber for cationic dye removal

Herein, in-house built heating chamber aided facile preparation of biochar was carried out using Bangladeshi sprouted corncob as the precursor for removing methylene blue (MB). The corncob biomass (CCB) was pyrolyzed at 700 °C for 2hrs (heating rate: 10 °C/min) using the in-house built heating chamber in a muffle furnace, eliminating the necessity of pyrolytic chamber. The prepared corncob biochar (CCBC) was characterized for elemental composition, crystallinity (XRD), functional groups (ATR-FTIR), surface morphology-elemental composition (SEM-EDX), surface area (BET), surface charge (point of zero charge), particle size-stability (DLS-zeta potential) and thermal stability (STA). Adsorption efficacy of CCBC was investigated in batch experiment with MB dye as well as effect of various factors such as contact time (5–120 min), initial MB concentration (7–15 mg/L), pH (2–10) and adsorbent dosage (10–35 mg). Without any chemical treatment for activation, CCBC produced maximum adsorption capacity (Qmax) of 20.42mgg−1 at 25 °C. The adsorption behavior of MB by CCBC could be better understood by Langmuir isotherm and Pseudo-second order kinetic model as they were the best fitted isotherm and kinetic models. Thus, waste to treat waste, meaning agricultural wastes like corncob can easily be converted into effective adsorbent for treating dye bearing wastewater

Exploration of photo-catalytic activity of nano-hydroxyapatite based on the crystallographic parameters: Estimation of crystallite size using X-ray diffraction data

Nano-hydroxyapatite was synthesized from CaCO3 and waste eggshells reacting with ortho-phosphoric acid, and titanium was doped to enhance the photocatalytic activity. The sample was characterized by X-ray diffraction technique, and different crystallographic parameters were explored focusing on crystallite size, microstrain, crystallinity index, lattice parameter, degree of crystallinity, microstrain, volume fraction of β-TCP, percentage of HAp, percentage of β-TCP, dislocation density, volume of unit cell, etc. To justify nano-crystallite size different models and equations such as the Williamson-Hall plot, linear straight -line model, Monshi-Scherrer model, Sahadat-Scherrer model, etc were employed. The effects of photocatalytic activity of synthesized hydroxyapatites were evaluated by varying the dye concentration, pH, interaction time, catalyst dose, and light source (halogen and sunlight). The photocatalytic activity was evaluated by degrading Congo Red dye and a relation was built between crystallographic parameters and catalysis. An easy degradation mechanism was also proposed for the Congo red dye using hydroxyapatite

Environmental remediation by hydroxyapatite: Solid state synthesis utilizing waste chicken eggshell and adsorption experiment with Congo red dye

This study reports the adsorption efficacy of hydroxyapatite (HAp) for removing Congo Red (CR) dye from aqueous solution. HAp was synthesized utilizing chicken eggshell as a precursor of Ca source. Solid state synthesis method was implemented which comprised calcination at 950 °C (E-HAp950). XRD analysis confirmed the formation of bi-phasic HAp with 15.5% of β-TCP. Elemental composition was evaluated by XPS and EDX analysis. FESEM analysis revealed the particles are of plate and spherical shaped also confirmed by the TEM images. DLS particle size, zeta potential, BET surface area and point of zero charge were also evaluated. Adsorption efficacy of E-HAp950 for removing CR was evaluated by batch adsorption experiment. Maximum adsorption capacity (qmax) was found to be 9.64 mgg−1 which was best explained by the non-linear fitting (R2 = 0.98) of Langmuir isotherm. Adsorption kinetics profusely followed pseudo second order kinetic model (R2 = 0.999) with qe (experimental) being very much closer to qe (calculative) for this model. Thus, hydroxyapatite prepared by utilizing eggshell waste through solid state method has the potential to remove toxic dyes