Migration of pseudoestrogen bisphenol A from various types of paper with thermochromic prints to artificial sweat solutions

Bisphenol A monitoring during anaerobic degradation of papers with thermochromic prints in soil

Pseudoestrogene bisphenol A (BPA) can be important ingredient of thermochromic inks, increasingly used materials in thermal printing paper, security printing, advertising, design and as temperature indicators in medicine and food industry. BPA mass fraction in thermochromic inks can be up to several percent. Hence, disposal of items with thermochromic prints pose a risk of environmental pollution. In this work BPA mass fraction was monitored during anaerobic degradation of papers with thermochromic prints in soil in both matrices: papers and soil. The degradation conditions simulated deeper layers of waste at a landfill site. Six types of papers with prints of thermochromic ink containing 2% of BPA were subjected to anaerobic degradation over up to 150 days. Initial mass fractions of BPA in papers decreased form (126-460) μg/g to (<QL - 45) μg/g after 150 days. BPA amounts were reduced 10 to 50 times depending on the paper type: least for synthetic paper and most for wood-free coated. For soil analysis new HPLC-UV method was developed and validated. The method was linear from 0.75 ng/g to 0.6 μg/g of BPA in soil with correlation coefficient of 0.9994. Method precision was 4.4%, accuracy 83% and detection limit 0.9 ng/g. Expectedly, amount of BPA in soil was increasing during the experiment. Mass fractions of BPA in soil were from not detected in earlier stage of degradation to (4.9-23.2) ng/g after 150 days. Final BPA amounts in soil were similar to those found in industrial, urban and agricultural soils worldwide. Hence, BPA from papers with thermochromic prints was notably decomposed, and contaminated soil had the capacity to absorb and decompose BPA even under anaerobic conditions. After 150 days of anaerobic degradation, only up to 1.86% of BPA contained in paper prints was found in soil, whilst, on average, 4% of initial BPA remained in paper.

Description of Thermochromic Offset Prints Morphologies Depending on Printing Substrate

In this study, the influence of physio-chemical properties of four printing substrates, fibrous papers (filter, bulky, recycled), and polymer film (synthetic paper) on the size of the thermochromic (TC) prints microcapsules was investigated. Results indicate that interaction between thermochromic ink and printing substrate determine the print morphology, i.e., porosity and roughness of printing substrate affect dimensions of TC microcapsules of resulting prints, while ink adhesion affects dimensional changes during heating–cooling cycle. Atomic force microscopy (AFM) analysis showed that microcapsules of the prints, on the surface of the smoothest synthetic paper, possess the smallest diameter and height, while, on the most porous and the most roughened surface of F paper, the microcapsules of the prints possess the highest diameter and height. By increasing the temperature to 40 °C, the biggest changes in the shape of the microcapsules (increase in height and decrease in diameter) were obtained using the surface of the hydrophilic filter paper. While using the recycled paper surface, the situation is opposite; the height and diameter of the microcapsules are reduced, and the microcapsules penetrate deeper into the paper structure (due to optimum adhesion). On the bulky paper surfaces, which are more hydrophobic than recycled paper (higher interfacial tension), the increase of temperature does not cause any significant changes in the shape and position of the microcapsules. The same behavior is observed using hydrophobic non-porous synthetic paper.