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One of the major pollutants in water resources are organic dyes that are widely used by different industries. Methylene blue (MB) is one of them which is quite harmful for aquatic life. This pollutant must be removed with proper methods. Adsorption is one of the most popular methods because of its high purification yield and known as a cost effective process if the sorbent is inexpensive. In this study, biochar which is used as an adsorbent has been produced from hazelnut shells used as the raw material. Chemical, thermal and surface characteristics of raw hazelnut shell were investigated by FT-IR, TG/DTG, SEM and elemental analysis. Biochar characteristics were determined by FT-IR, BET and SEM analysis. The effect of different adsorption parameters such as pH, initial dye concentration, contact time, adsorbent dosage and temperature on the adsorption of MB onto hazelnut shell char were examined in batch experiments. The equilibrium of adsorption was modeled using Langmuir and Freundlich isotherm models. The maximum adsorption yield of MB was found to be 83% at pH 4.0, adsorbent dosage of 4 g/L, contact time of 300 min., initial dye concentration of 15 mg/L and temperature of 45 o C. In addition, the Freundlich isotherm was found to be the best fitting isotherm model for the adsorption process. The pseudo-first-order and pseudo-second-order kinetic models were applied to the experimental data and thermodynamic parameters such as Gibbs free energy, enthalpy and entropy were determined.

Rotary Friction welding is one of the most popular methods of joining similar and dissimilar materials. It is widely used with metals and thermoplastics in a wide variety of aviation, transport and aerospace industrial component designs. This study investigates the influence of friction and upsetting pressures on the hardness, tensile properties and microstructure of the welds. The experimental results showed that as the friction and upsetting pressures increased, the hardness and tensile strength values increased, as well. The tensile fracture of welded joint occurred in the AISI 1060 side. The friction processed joints were evaluated for their integrity and quality aspects by optical and scanning electron microscopy. For the perfect interfacial bonding, sufficient upsetting and friction pressures are necessary to reach the optimal temperature and severe plastic deformation to bring these materials within the attraction range.Keywords: Welding, Mechanical properties, MicrostructureZgrzewanie tarciowe jest jedną z najbardziej popularnych metod łączenia podobnych i odmiennych materiałów. Jest ono powszechnie stosowane do łączenia metali i tworzyw termoplastycznych w szerokim zakresie wzorów części przemysłowych w lotnictwie, transporcie i przemyśle kosmicznym. Celem badań jest określenie wpływu tarcia i nacisków na twardość, właściwości wytrzymałościowe i mikrostrukturę spoiny. Wyniki doświadczalne wykazały, że zewzrostem tarcia i nacisków wzrosła twardość i wytrzymałość na rozciąganie. W trakcie prób rozciągania pękanie następowało po stronie stali AISI 1060. Zgrzewane tarciowo spoiny zostały oceniopne pod względem ich integralności i jakości za pomocą mikroskopii optycznej i skaningowej mikroskopii elektronowej. Dla uzyskania idealnego złączenia materiałów potrzebne są odpowiednie naciski i tarcie, aby osiągnąć optymalną temperaturę i intensywne odkształcenie plastyczne.