Volume 12 Issue 2

Recycled paper is an important raw material to provide sustainability of natural resources and reduce the environmental impact of the use of paper from recycled pulp in the packaging industry. Hence, recycled paper production is higher in terms of volume and utilization. Recycled paper products are used in the packaging industry partially or fully. Such usage leads to the presence of heavy metals due to recycled and chemical additive sources. The present study aims at determining the amounts and also identifying the sources of heavy metals such as Pb, Cd, Zn, Ni, and Cu contained in recycled testliner (TL) and fluting (FLT), which are main products used in production of corrugated cardboard. The metals in the structure of the paper used in packages directly or indirectly in contact with foods are heavy metals. Mean values of 2.6 mg kg-1 Pb (lead), 2.8 mg kg-1 Zn (zinc), 0.094 mg kg-1 Cd (cadmium), 1.8 mg kg-1 Ni (nickel), and 25.4 mg kg-1 Cu (copper) were detected in test liner and fluting papers using inductively coupled plasma optical emission spectrometry (ICP-OES). The main sources of heavy metals are colorants, mainly consisting of conventional paint and pigments as well as spot and Pantone Matching System (PMS) colorants.

Pipes that are light in weight are necessary for convenience and to reduce the cost of transportation and installation. A new design of glass fiber reinforced plastic (FRP) pipe with a bamboo and veneer layer is presented in this paper. The core layer of the sandwich structure of the pipe wall is made of bamboo and veneer, and the inner and outer layers are FRP. Range analysis and variance analysis of orthogonal experiments were conducted to investigate the effect of fiber stress, winding angle, and core material on the mechanical performance of the pipes subjected to shearing and parallel-plate loading tests. The results indicated that the new design of FRP pipe with a bamboo and veneer layer was feasible, and the pipe had better mechanical performance with a fiber stress of 300 N, a winding angle of 30°, and a core material of bamboo. Core material was the most influential factor in mechanical performance. The average density of pipes was 0.94 g/cm3, approximately half that of the glass fiber reinforced plastic mortar (GRPM) pipes. The FRP pipe offered advantages in terms of weight savings and improved mechanical performance, and it showed a great application potential for the future.

Defects have a serious impact on the load carrying capacity and the safety of ancient architectural wood members. Common screening methods to identify defects cause damage to this wood. To protect ancient architecture, it is necessary to develop a method that can screen for internal defects and estimate their size quickly and efficiently without destruction. This paper studied the detection mechanism of the sound hammering method for screening internal defects in wood. Wood members generated different kinds of vibration through hammering experiments, and the vibration produced by hammering wood with internal-hole defects was divided into three kinds: local surface vibration, the whole structure vibration, and defective-part vibration. The parameters and their variation of these three kinds of vibration were investigated by a mechanical vibration simplified model, and the method for screening the internal defects based on sound hammering was proposed. The feasibility of the method was verified by experiments.

The use of micro-size samples is becoming more important to determine the mechanical properties of wood. The aim of this study was to investigate the effect of the loading rate on the micro-mechanical properties of Scots pine (Pinus sylvestris L.) wood. The bending strength, modulus of elasticity in bending, compression strength parallel to the grain, and tensile strength parallel to the grain were determined using micro-size test samples. Three different loading rates were used for each test. The first loading rates were determined according to related ISO standards, and the second and third loading rates were determined as half- and quarter- of the standard loading rates. The results showed that the loading rate had significantly affected the modulus of elasticity and compression strength of Scots pine wood. However, the loading rate had no significant effect on the bending and tensile strength of the Scots pine wood. When the loading rate decreased, the mechanical properties of micro-size Scots pine wood were decreased.

In order to utilize the leftover materials from traditional Chinese medicine production and to remove antibiotics from wastewater, extracted herbal residues were used as raw materials to produce activated carbon. To keep a constant quality and adsorption ability across cephalosporin antibiotic samples, all samples were divided into rhizomes, fruits, and leaves to make activated carbon by step-wise carbonization and overheated steam activation. The three kinds of carbon were mixed in the optimal ratio of 5:4:2, which had homogeneity in quality with a high adsorption capacity. Maximum adsorption of the mixture to cefalexin and cefradine were 7.1 mg/g, and the mixture removed 84% of the antibiotics from treated wastewater. Approximately 90% of the antibiotics was desorbed after ultrasonic treatment of the distilled water-carbon mixture for 10 min, and a re-adsorption capacity of 80% was maintained for next use. The adsorption process is dominated by a pseudo-second order kinetic reaction, with two active sites binding to one antibiotic molecule. The rate-limiting step is an intra-particle diffusion process. The isothermal adsorption process conforms to Langmuir and Tempkin isotherm models, showing multilayer and physical adsorption. The activated carbon from herbal residues can adsorb a low concentration of antibiotics in wastewater and be recycled after ultrasonic treatment.