Thermal Study and Emission Characteristics of Rice Husk Using TG-MS

Workplace concentrations of particulate matter and noise levels among stone quarry and soil brick-making workers in Tanzania

This study was conducted in 15 artisanal stone quarries (SQ) and 22 soil brick-making (SBM) sites. Specific objectives were to: (i) quantify ambient concentrations of suspended particulate matter (PM) and gaseous pollutants and noise levels at SQ and SBM workplaces; (ii) critically evaluate the potential workplace hazards, and risk factors; and (iii) analyze potential health risks to workers. Gaseous pollutants, PM, and noise levels were measured by using portable digital devices. Social demographic information of 150 workers across the study sites was collected using a questionnaire. Quantitative data were summarized and exploratorily analyzed using Stata software. This study revealed that fuel burning in the SBM releases SPM up to 10-fold and CO gas up to 14-fold above the WHO-recommended time-weighted average exposure concentrations of 16.6 µg/m3 and 0.3 mg/m3, respectively. On average hitting with a pickax in SQ areas released noise levels of about 81.01 ± 6.8 dB[A]. Overall, the SQ and SBM workers were exposed to low concentrations of PM and noise levels when the measurements were taken. Long working hours for repetitive activities in hot-sunny (27.1 ± 2.3 °C) and low outdoor humidity 23 ± 1.5%, potentially increase epidemiological risks to vulnerable individuals and enhance worker exposures to inhalable PMs. Although workplace noise exposure below the regulatory threshold of 85 dB[A] may not cause immediate hearing damage, it can have a significant impact on workers' hearing health, cognitive performance, psychological well-being, and overall productivity. This study provides an overview of workplace conditions rather than an accurate representation of the actual worker exposure levels because personal breathing zone sampling devices were not used. This study provides baseline information for further research and can be used for evidence-based decision-making and policy formulation to safeguard worker safety and health in SQ and SBM sites in Tanzania.

Thermal Hazard Evaluation of Tert-Butyl Peroxy-3,5,5-trimethylhexanoate (TBPTMH) Mixed with Acid-Alkali

Tert-butyl peroxy-3,5,5-trimethylhexanoate (TBPTMH), a liquid ester organic peroxide, is commonly used as an initiator for polymerization reactions. During the production process, TBPTMH may be exposed to acids and alkali, which may have different effects on its thermal hazard, so it is necessary to carry out a study on the thermal hazard of TBPTMH mixed with acids and alkali. In this paper, the effects of H₂SO₄ and NaOH on the thermal decomposition of TBPTMH were investigated by differential scanning calorimetry (DSC) and adiabatic calorimetry (Phi-TEC II). The “kinetic triple factors” were calculated by thermodynamic analysis. The results show that the three E_a are 132.49, 116.36, and 118.24 kJ/mol, respectively; thus, the addition of H₂SO₄ and NaOH increased the thermal hazard of TBPTMH. In addition, the characteristic parameters (time to maximum rate under adiabatic conditions, self-accelerated decomposition temperature) of its thermal decomposition were determined, and the control temperature (45, 40, and 40 °C) of TBPTMH under the action of acid-alkali were further received. This work is expected to provide some guidance for the safe storage, handling, production, and transportation of TBPTMH in the process industry.

The Course and the Effects of Agricultural Biomass Pyrolysis in the Production of High-Calorific Biochar

The thermal pyrolysis of agriculture biomass has been studied in a fixed-bed reactor, where the pyrolysis was conducted at a steady temperature of 800 °C. This work analyses the pyrolysis products of six agricultural wastes: pistachio husks, walnut husks, sunflower hulls, buckwheat husks, corncobs and coconut shells. The conducted research compared examples of large waste biomass streams from different parts of the world as a potential source of renewable energy. Additionally, the kinetics of the reaction with the activation energy were analyzed and calculated for all raw materials in pyrolysis process. Biochars are characterised by higher combustion heat in comparison to the raw material samples. The average value of the heat of combustion increased due to pyrolysis process from 10 MJ/kg, with minimal value of 2.7 MJ/kg (corncob) and maximum of 13.0 MJ/kg for coconut, which is also characterised by the maximal absolute combustion heating value (32.3 MJ/kg). The increase in calorific values varied from 15% to 172% (with 54% reference for wood chips), which indicates that charring is an effective method for increasing the energy concentration. The obtained biochar were compared with wood chips, which are widely used solid fuel of organic origin. The studied biomass-derived fuels are characterised by lower ash contribution than wood. An analogous observation was made for the obtained biochars, whose ash contribution was lower than for the chips in terms of both unit-mass and unit-combustion-heat. The main advantage of this method is the production of solid fuel from biomass, which increases the calorific value and bulk density of biochar in comparison to raw material.