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The aim of this study was to examine the best electrode design for the electrocoagulation process with the best removal performance, reduced passivation on the electrode surface, and lower energy consumption requirements for removing Chromium (Cr) and Lead (Pb) from leather tannery effluent. Three different electrodes were compared: non-rotating disk electrode (NRDE), rotating disk electrode (RDE) and rotating disk mesh electrode (RDME). All electrodes were used to observe a reduction in passivation on the electrode surface and its effects on the removal performance of Cr and Pb. The material used for the electrodes was iron. The maximum removal efficiency obtained was Cr = 87.9% and Pb = 97.5% under the following operating conditions: pH = 7, treatment time = 90 min, current density = 6.57 mA/cm², and RPM = 80. The results show that the electrical energy requirement for treating chromium and lead using RDME was 4.5 kWh/m³, which was found to be lower than the energy requirement observed in various other studies for treating tannery effluent. According to the results, RDME shows the highest removal performance with lower specific energy consumption compared to NRDE and RDE. RDME can be efficiently employed at a larger scale for treating leather tannery effluent.

Medium carbon steel is widely consumed by various industrial sectors due to its attractive set of mechanical properties and low cost, but it experiences deterioration when exposed to a corrosive environment. In the present study, Aloe Vera plant extract was studied as a green corrosion inhibitor for medium carbon steel in an acidic medium. The presence of inhibitive compounds in Aloe Vera plant extract was determined by FTIR. Moreover, the inhibition efficiency was determined through gravimetric analysis and electrochemical analysis. The results show that the Aloe Vera plant extract provided inhibition efficiency of more than 90% in both gravimetric and electrochemical analyses. Furthermore, the shift in polarization curves depicts that this plant extract is a mixed type inhibitor acting as an anodic and cathodic inhibitor. Overall, Aloe Vera plant extract provides excellent corrosion inhibition to medium carbon steel in the H2SO4 environment and can be used as a green corrosion inhibitor for mitigating internal corrosion of pipelines and storage tanks.

The compounding of Polyvinylchloride (PVC) with some additives was studied for the enhancement of physical and mechanical properties. Two categories of formulations (un-plasticized and plasticized PVC) were prepared with PVC (K value ranging from 60 to 70) taking as base polymer. Different additives generally categorized as plasticizers, fillers, stabilizers, pigments and processing aids, were mixed in the standard concentration unit “parts per hundred resins (phr)” with base polymer. Cable compound and shoe compound were prepared in plasticized-PVC category containing mainly plasticizing additives like diisooctyl phthalate (DIOP) (40 phr) and epoxidized soybean oil (2-3 phr) with general plasticizer (50-80 phr) respectively. Whereas the rigid pipe and sheet compounds were prepared as un-plasticized PVC category containing different fillers/stabilizers like tribasic lead sulphate (6 phr), lead stearate (1 phr), glyceryl monostearate (0.4 phr) in rigid pipe and butylin mercaptides (2-2.5 phr), fatty alcohol and fatty acid ester (0.5-0.8 phr) in rigid sheet compound. Experimental investigation was carried out for analyzing the mechanical properties like tensile strength, elongation at break, hardness and physical property i.e. specific gravity for the compounded samples. An appreciable increase was observed in tensile strength from 460 Kg/cm2 (base PVC-polymer) to a range of 550 Kg/cm2 for un-plasticized PVC compounds (rigid PVC-pipe and sheet) with little increase in elongation at break from 56% (base polymer) to 124.33% and 150% (for Pipe and Sheet compounds respectively). On the other side the elongation at break for plasticized PVC compounds was increased from 56% to 250.67% (for cable compound) and 351.33% (for shoe compound), where as the tensile strength was decreased from 460 Kg/cm2 to 150.33 Kg/cm2 (for cable compound) and 120.33 Kg/cm2 (for shoe compound). The hardness (shore A, D) was increased from 40 to 80 for all the compounds except shoe compound with hardness of 65.33. The impact of plasticizers was found in direct proportion on elongation at break but having inverse proportion on tensile strength.