Statistical prediction and sensitivity analysis of kinetic rate constants for efficient thermal valorization of plastic waste into combustible oil and gases.

Sensitivity analyses of rate constants for chemical kinetics of the pyrolysis reaction are essential for the efficient valorization of plastic waste into combustible liquids and gases. Finding the role of individual rate constants can provide important information on the process conditions, quality, and quantity of the pyrolysis products. The reaction temperature and time can also be reduced through these analyses. For sensitivity analysis, one possible approach is to estimate the kinetic parameters using MLRM (multiple linear regression model) in SPSS. To date, no research reports on this research gap are documented in the published literature. In this study, MLRM is applied to kinetic rate constants, which slightly differ from experimental data. The experimental and statistically predicted rate constants varied up to 200% from their original values to perform sensitivity analysis using MATLAB software. The product yield was examined after 60 min of thermal pyrolysis at a fixed temperature of 420 °C. The predicted rate constant "k(8)" with a slight difference of 0.02 and 0.04 from the experiment revealed 85% oil yield and 40% light wax after 60 min of operation. The heavy wax was missing from the products under these conditions. This rate constant can be utilized to maximize the commercial-scale extraction of liquids and light waxes from thermal pyrolysis of plastics.

Sensitivity Analysis of Thermal Degradation of Plastic Waste Using Statistically Assumed Exponential Factors and Activation Energies.

The rise in the production of plastic waste has prompted the exploration of various recovery options instead of landfilling, burning, and other unethical ways of decomposing. The experimentally generated rate constants for the thermal processing of plastic waste do not yield enough liquid fuels and gases for commercial-scale usage. It is imperative to predict kinetic rate constants statistically using an appropriate combination of activation energies (E a) and frequency factors (A o) for the optimized thermal valorization of plastic waste. This approach also assists in controlling the selectivity and quantity of the pyrolysis products. A statistical kinetic model was tested to find the best combination of rate constants from different combinations of E a and A o to pyrolyze the high-density polyethylene. Two series of E a and A o were first assumed using R software. These series were then used to predict kinetic rate constants and analyze their sensitivity independently using MATLAB. The rate constants were varied from their originally predicted values during the sensitivity analysis. It was found that the rate constant k(7) dominated the other predicted rate constants where high oil and gas yields were concerned. The gas yield increased from lower to higher extreme positions in the range of 60%-74% with the first series and from 65% to 81% with the second series. The maximum oil content was found around 74% and 65% with the first series and second series, respectively.

Transcutaneous face-lift.

BACKGROUND: Face-lifting can result in a number of complications. A mini-invasive technique is now presented. OBJECTIVE: To perform face-lifting as a simple, quick, and mini-invasive ambulatory approach in patients requiring mild to moderate lift. MATERIALS AND METHODS: Using a Khawaja-Hernandez or Keith needle and polypropylene 2-0, the superficial SMAS is pulled up and fixed to the periosteum of the temporal bone. Nineteen patients were so operated on, 14 women and 5 men, whose ages varied from 51 to 67 years. Pre- and postoperative photographs were taken. The degree of satisfaction was measured from 1 to 3 (1 being the least satisfactory). Informed consent was signed by all of the patients. RESULTS: Satisfactory results were obtained in all cases. Patients enjoyed the ease of the procedure. CONCLUSION: This is a simple, quick, and noncomplicated way to perform a face-lift. It can be combined with other modalities of facial rejuvenation.

A percutaneous approach to eyebrow lift: the Salvadorean option.

BACKGROUND: Surgical eyebrow lift can result in a number of complications. A nonsurgical simple method of lifting the brow is presented. OBJECTIVE: To raise the eyebrows using a simple, quick, and noninvasive approach. METHODS: Twenty-nine patients, 27 women and 2 men, whose ages varied from 24 to 56 years (mean of 32 years) were included in the study. Preoperative and postoperative photographs were taken. In two patients, brow suspension was performed at the time of blepharoplasty. Informed consent was signed by all of the patients. For measuring the degree of satisfaction of the patients, we gave to them a sheet grading it from one to three (with one being the least satisfactory). Local anesthesia (1% lidocaine, 1:400,000 epinephrine), a conveniently sized Keith needle, and prolene 3/0 sutures were used. RESULTS: Satisfying results were obtained in all cases. The only problem encountered in two patients was temporary edema, and it settled in a few days. CONCLUSION: This is a very simple, quick, and noncomplicated method of raising the eyebrows. It can be repeated, revised easily, or combined with other modalities, such as peels, topical tretinoin, oral isotretinoin, fat injection, Goretex, and Botox as part of a facial rejuvenation program.